MEDICAL    >§CH<S>(DL 


-DR.    S«J.S.  ROGERS 


MANUAL 


DISSECTION  OF  THE  HUMAN  BODY 


HOLDEN'S  MANUAL 


EDITED     BY 


LUTHER  (HOLDEN 


PRESIDENT  OK  THE  ROYAL  COLLEGE  OP  SURGEONS  OF  ENGLAND  :   MEMBER  OF  THE  COUUT  OF  EXAMINERS 
SENIOR  SURGEON  TO  ST  BARTHOLOMEW'S  AND   THZ  FOUNDLING  HOSPITALS 


.  JOHN   LANGKTON,   F.K.C.S. 

ASSISTANT-SURGEON  AND  LECTURER  ON  ANATOMY  AT  ST  BARTHOLOMEW'S  HOSPITAf. 


ILLUSTRATED    WITH    NUMEROUS    WOOD    ENGRA VINOS 


FOURTH    EDITION 


H 


TO 

THE    STUDENTS 

OF 

ST    BARTHOLOMEW'S   HOSPITAL 

IN     THE     HOPK     THAT     IT     MAY     ASSIST     THEM    'IN     THEI1J 
ANATOMICAL     STUDIES 

$fns  Usfmtual  is  iptbualtfr 

BT    THKIU    FAITHFUL    VHIENI)    AND    \VEI.L-WISHER 

THE   AUTHOR 


47<i 


PEE  FACE 

TO 

THE     FOURTH    EDITION. 


IN  THIS  EDITION  the  Editors  have  most  carefully  revised  the 
entire  work.  The  order  of  dissection  has  been  here  and  there 
altered ;  and  further  illustrations  and  additional  matter  intro- 
duced, especially  concerning  the  Anatomy  of  the  Nervous  System 
and  the  Senses. 

The  object  throughout  has  been  to  be  as  concise  as  possible, 
and  to  put  the  subject  in  as  clear  and  practical  a  light  as 
is  compatible  with  the  faithful  handling  of  its  natural  diffi- 
culties. 

It  is  hoped  that  the  work,  in  its  present  form,  is  adapted, 
not  only  for  students,  but  for  members  of  the  profession  who 
wish  to  refresh  their  anatomical  knowledge. 

Our  best  thanks  are  due  to  the  Demonstrators  of  Anatomy 
at  St.  Bartholomew's  Hospital  for  valuable  suggestions. 


65  GOWEK  STREET  : 
October  1879. 


CONTENTS. 


PAGE 

DISSECTION  OF  THE  SCALP 1 

DISSECTION  OP  THE  NECK     .        .        ..   ,~       .--....        .    .  17 

COURSE  AND  RELATIONS  OF  THE  SUBCLAVIAN  ARTERIES  .    --.<       .        .  60 

DISSECTION  OF  THE  FACE v       ...  73 

MUSCLES  OF  MASTICATION.    TEMPORAL  AND  PTERYGO-MAXILLARY  REGIONS  94 

BRANCHES  OF  THE  INTERNAL  MAXILLARY  ARTERY  IN  THE  THREE  STAGES 
OF  ITS  COURSE •  ;      ..        ....  100 

BRANCHES  OF  THE  INFERIOR  MAXILLARY  NERVE 104 

DISSECTION  OF  THE  HEART       .  .        .    .    .        .        .        .        .  155 

FCETAL  CIRCULATION     .        .        .        .   •    .        .        .        .        .        .    .  168 

STRUCTURE  OF  THE  LUNGS        .     *  ,   ,r  .      -.        .       ....        •        •  169 

DISSECTION  OF  THE  PHARYNX      .        .       _.v       .        .        .        .        .    .  177 

DISSECTION  OF  THE  LARYNX     .        .        .        ...•„.        .        .        .        .  189 

DISSECTION  OF  THE  TONGUE 201 

DISSECTION  OF  THE  ORBIT .        .        .  206 

DISSECTION  OF  THE  SUPERIOR  MAXILLARY  NERVE       .        .        .        .    .  218 

DISSECTION  OF  THE  EIGHTH   PAIR  OF  NERVES  AT  THE  BASE  OF  THE 
SKULL 224 

DISSECTION  OF  THE  NOSE     .  228 


X  CONTENTS. 

PAOK 

DISSECTION  OF  THE  MUSCLES  OF  THE  BACK 234 

LIGAMENTS  OF  THE  SPINE    .        .        .  240 

DISSECTION  OF  THE  UPPER  EXTREMITY 255 

DISSECTION  OF  THE  AXILLA          .        .   §    .        .        .        .        .        .    .  261 

DISSECTION  OF  THE  UPPER  ARM .        .  271 

DISSECTION  OF  THE  FRONT  OF  THE  FOREARM      .      . .      ,  *        .        .    .  285 

DISSECTION  OF  THE  PALM  OF  THE  HAND 297 

MUSCLES  OF  THE  BACK  CONNECTED  WITH  THE  ARM 310 

DISSECTION  OF  THE  MUSCLES  OF  THE  SHOULDER 317 

DISSECTION  OF  THE  BACK  OF  THE  FOREARM 325 

DISSECTION  OF  THE  LIGAMENTS      , 338 

DISSECTION  OF  THE  ABDOMEN       .        .  '"' 353 

DISSECTION  OF  THE  PARTS  CONCERNED  IN  INGUINAL  HERNIA          .        .  364 

PLAN  OF  THE  BRANCHES  OF  THE  CCELIAC  Axis 386 

DISSECTION  OF  THE  PELVIC  VISCERA        .        .        .  .        .        .411 

DISSECTION  OF  THE  MALE  PERINEUM 414 

ANATOMY  OF  THE  SIDE  VIEW  OF  THE  PELVIC  VISCERA  ....  428 
STRUCTURE  OF  THE  BLADDER,  PROSTATE,  URETHRA,  AND  PENIS          .    .  446 

DISSECTION  OF  THE  FEMALE  PERINEUM 459 

DISSECTION  OF  THE  FEMALE  PELVIC  VISCERA 463 

DISSECTION  OF  THE  ABDOMINAL  VISCERA         .        .        .        ...        .  475 

DISSECTION  OF  THE  LOWER  EXTREMITY 496 

ANATOMY  OF  THE  PARTS  CONCERNED  IN  FEMORAL  HERNIA     .        .        .  503 

DISSECTION  OF  THE  FRONT  OF  THE  LEG 525 

DISSECTION  OF  THE  GLUTEAL  REGION      .        .        .'•''".        .        .        .  533 

DISSECTION  OF  THE  BACK  OF  THE  THIGH    .        .        .        .        .        .    .  544 

DISSECTION  OF  THE  SOLE  OF  THE  FOOT 557 


CONTENTS.  xi 

PAGI? 

DISSECTION  OF  THE  LIGAMENTS 564 

DISSECTION  OP  THE  BRAIN 578 

DISSECTION  OF  THE  SPINAL  CORD 617 

DISSECTION  OF  THE  EYE   ....".....        .  631 

DISSECTION  OF  THE  ORGAN  OF  HEARING 648 

DISSECTION  OF  THE  MAMMARY  GLAND 663 

DISSECTION  OF  THE  SCROTUM  AND  TESTIS 665 

INDEX  .  673 


DISSECTION   OF  THE   HUMAN   BODY. 


DISSECTION   OF   THE  SCALP. 

AN  INCISION  should  be  made  from  the  root  of  the 
DISSECTION. 

nose  along  the  mesial  line  of  the  vertex  to  the 

external  protuberance  of  the  occipital  bone  ;  another,  horizontally 
round  each  half  of  the  head,  to  join  at  right  angles  the  two  ends 
of  the  first  incision.  These  incisions  must  not  divide  more  than 
the  skin,  so  that  the  subcutaneous  vessels  and  nerves  be  not  in- 
jured. It  is  well  to  dissect  on  one  side  of  the  head  the  muscles 
only,  reserving  the  other  side  for  the  dissection  of  the  vessels  and 
nerves. 

STRATA  COMPOS-  The  several  strata  of  tissues  covering  the  skull- 
ING  THE  SCALP.  cap  are — 1,  the  skin  ;  2,  a  thin  layer  of  adipose 
tissue  which  contains  the  cutaneous  vessels  and  nerves  and  the 
bulbs  of  the  hair ;  and  by  which  the  skin  is  very  closely  connected 
to,  3,  the  broad  thin  aponeurosis  of  the  occipito-frontalis  muscle 
(apoueurosis  of  the  scalp) ;  4,  an  abundance  of  loose  connective 
tissue,  which  permits  the  free  motion  of  the  scalp  upon,  5,  the 
pericranium,  or  periosteum  of  the  skull-cap. 

Immediately  beneath  the  skin,  then,  we  expose  the  thin  stratum 
of  adipose  tissue  which  connects  it  with  the  aponeurosis  of  the 
scalp.  It  forms  a  bed  for  the  bulbs  of  the  hair  and  for  the  rami- 
fications of  the  cutaneous  arteries.  The  toughness  of  this  tissue, 

B 


2  DISSECTION   OP    THE    SCALP. 

in  which  the  arteries  ramify,  does  not  permit  them  to  retract  when 
divided ;  hence  the  haemorrhage  which  follows  incised  wounds  of 
the  scalp  ;  hence,  also,  the  difficulty  of  drawing  them  out  with  the 
forceps. 

This  cutaneous  muscle  is  closely  connected  to  the 

OCCIPITO-FRON-  • 

TALIS  MUSCLE  scalp.  It  consists  of  two  fleshy  portions,  one  on  the 

AND  EPICRANIAL  occiput,  the  other  on  the  forehead,  connected  by  a 
APONEUROSIS.  broad  aponeurosis.  The  occipital  portion  of  the 

muscle  takes  origin  from  the  outer  two-thirds  of  the  upper  curved 
line  of  the  occipital  bone,  and  the  adjoining  part  of  the  mastoid 
process.  The  fibres  ascend  over  the  back  of  the  head,  and  terminate 
in  the  epicranial  aponeurosis.  The  frontal  portion,  commencing  in 
an  arched  form  from  the  epicranial  aponeurosis  near  the  coronal 
suture,  descends  over  the  forehead,  and  terminates  partly  in  the  skin 
of  the  brow,  partly  in  the  orbicularis  oculi  and  corrugator  super- 
cilii  and  in  the  internal  angular  process  of  the  frontal  bone.  Some 
fibres  run  down  the  nose  under  the  name  of  the  pyramidalis  nasi. 
The  aponeurosis  of  the  scalp  is  continued  over  the  temples  and 
side  of  the  head,  gradually  changing  from  tendinous  into  con- 
nective tissue.  This  muscle  enables  us  to  move  the  scalp  back- 
wards and  forwards.  But  its  chief  action  is  as  a  muscle  of  expres- 
sion. It  elevates  the  brows,  and  occasions  the  transverse  wrinkles 
in  the  expression  of  surprise.  It  is  supplied  by  the  posterior 
auricular  and  temporal  branches  of  the  facial  nerve. 

MUSCLES  OF  There  are  several  small  muscles  to  move  the 

THE  EAR.  cartilage  of  the  ear.  In  man  they  are  thin  and 

pale ;  but  in  animals  who  possess  a  more  delicate  sense  of  hearing, 
they  are  much  more  developed,  for  the  purpose  of  quickly  direct- 
ing the  cartilage  of  the  ear  towards  the  direction  of  the  sound. 

M.  ATTOLLENS  To  indicate  the  position  of  this  muscle  the 

AUBEM.  student  should  draw  down  the  upper  part  of  the 

pinna  of  the  ear,  when  it  will  be  found  immediately  under  the  ridge 
of  skin  so  produced.  It  arises  from  the  epicranial  aponeurosis,  and 
is  inserted  into  the  cranial  aspect  of  the  upper  part  of  the  concha. 

M.  ATTRAHENS  This  muscle  is  smaller  than  the  preceding, 

AUREM.  and  its  situation  is  indicated  by  the  prominence 


ARTEKIES    OP    THE    SCALP.  3 

of  skin  produced  by  drawing  backwards  the  front  part  of  the  helix. 
It  arises  from  the  aponeurosis  of  the  occipito-frontalis,  and  is  in- 
serted into  the  front  of  the  helix. 

M.  HETRAHENS  This  muscle  is  exposed  by  reflecting  the  skin 

AUEEM.  from  the  ridge  produced  by  drawing  the  pinna 

forwards.  It  proceeds  from  the  base  of  the  mastoid  process  to  the 
lower  part  of  the  concha.  The  retrahens  and  the  attollens  aurem 
are  supplied  by  the  posterior  auricular  branch  of  the  facial  nerve  ; 
the  attrahens,  by  an  offset  from  the  temporal  branch  of  the  same 
nerve. 

ARTERIES  OF  The  arteries  of  the  scalp  are  derived,  in  front, 

SCALP.  from  the  supra-orbital  and  frontal  arteries, 

branches  of  the  ophthalmic  artery  which  is  a  branch  of  the  internal 
carotid ;  on  the  sides,  from  the  temporal ;  behind,  from  the  occi- 
pital and  posterior  auricular,  all  branches  of  the  external  carotid. 

The  Jrontal  emerges  from  the  orbit  at  its  inner  angle ;  it  runs  up- 
wards for  a  short  distance  and  inosculates  with  the  following  artery. 

The  supra-orbital  passes  through  the  supra-orbital  notch  and  dis- 
tributes branches,  some  of  which  ascend  towards  the  top  of  the  head  and 
communicate  with  the  temporal  artery. 

The  temporal,  about  an  inch  and  a  half  above  the  zygoma,  divides  into 
two  branches — an  anterior  and  a  posterior.  The  anterior  runs  forwards 
in  a  tortuous  course  and  anastomoses  with  the  supra-orbital  artery ;  the 
posterior  (usually  the  larger)  arches  backwards  over  the  ear,  and  its 
branches  communicate  with  the  corresponding  branch  of  the  opposite 
side  and  with  the  occipital  and  posterior  auricular  arteries. 

The  posterior  auricular  is  a  small  vessel  seen  in  the  cleft  between  the 
ear  and  the  mastoid  process  :  it  ascends,  and  divides  into  two  branches  : 
one,  which  passes  backwards  and  inosculates  with  the  occipital,  the  other, 
which  runs  forwards  above  the  ear  and  communicates  with  the  temporal 
artery. 

The  occipital  may  be  noticed  piercing  the  trapezius  near  to  the 
external  occipital  protuberance  ;  ascending  over  the  back  of  the  head,  it 
divides  into  numerous  branches  which,  inosculate  with  the  preceding 
arteries. 

The  veins  of  the  scalp  accompany  their  respective  arteries. 

B  2 


NEBVES    OF    THE    SCALP. 


NERVES  OF  THE 
SCALP. 


The  sensory  nerves  of  the  scalp  are  supplied 
from  each  of  the  three  divisions,  namely  the 
ophthalmic,  the  superior  maxillary  and  inferior  maxillary,  of  the 
fifth  pair  ;  also  from  the  second  cervical  nerve.  The  nerves  to  the 
muscles  of  the  scalp  and  ear  come  from  the  portio  dura  or  seventh 
pair  (fig.  1  ). 

Fia.  1. 


DIAGBAM  OF  THE  NERVES  OF  THE  SCALP. 


1.  Supra-  trochlear. 

2.  Supra-orbital. 

3.  Temporal  br.  of  the  superior  maxillary. 

4.  Auriculo-temporal  br.  of  the  inferior  maxillary. 


5.  Facial  represented  by  dotted  lines. 

6.  Posterior  auricular. 

7.  Small  occipital. 

8.  Great  occipital. 


The  supra-trochlear  nerve  is  derived  from  the  frontal  branch  of 
the  ophthalmic  division  of  the  fifth.  It  appears  at  the  inner  angle 
of  the  orbit,  and  supplies  the  skin  of  the  forehead,  and  the  upper  eyelid. 

The  supra-orbital  nerve  is  a  continuation  of  the  frontal  branch  of  the 
fifth.  It  emerges  from  the  orbit  through  the  notch  in  the  frontal  bone, 
and  subdivides  into  branches,  which  are  covered  at  first  by  the  fibres  of 
the  orbicularis  and  occipito-frontalis  ;  but  they  presently  become  subcu- 
taneous, and  terminate  in  two  branches  —  an  inner,  which  ascends,  to 


NEEVES    OF   THE    SCALP.  5 

supply  the  structures  as  high  as  the  parietal  bone ;  and  an  outer  and 
larger,  which  may  be  traced  over  the  vertex  as  far  as  the  occipital  bone. 

The  temporal  branch  of  the  superior  maxillary  nerve  pierces  the 
temporal  aponeurosis  about  an  inch  above  the  zygoma,  and  is  distributed 
to  the  skin  of  the  temple,  communicating  with  the  facial  nerve  and  occa- 
sionally with  the  following. 

The  auriculo-temporal  nerve,  a  branch  of  the  inferior  maxillary  nerve, 
after  sending  a  small  filament  to  the  upper  part  of  the  pinna,  divides  into 
two  branches  which  accompany  the  divisions  of  the  superficial  temporal 
artery ;  of  these  the  posterior  is  the  smaller. 

The  temporal  branches  of  the  facial  nerve  lie  superficial  to  the  tem- 
poral aponeurosis,  and  supply  the  attrahens  aurem,  the  orbicularis 
oculi,  the  occpito-frontalis,  and  the  corrugator  supercilii. 

The  posterior  auricular  nerve  is  a  branch  of  the  facial,  and  divides 
like  its  accompanying  artery  behind  the  pinna  of  the  ear,  into  a  posterior 
or  occipital  branch,  which  supplies  the  posterior  belly  of  the  occipito- 
frontalis,  and  into  an  anterior  or  auricular  branch,  which  ends  in  the 
auricle,  the  retrahens  aurem  and  the  attollens  aurem. 

The  great  occipital  nerve  is  the  posterior  branch  of  the  second  cervical 
nerve.  After  piercing  the  complexus  it  appears  on  the  occiput  with  the 
occipital  artery,  and  divides  into  wide-spreading  branches  which  supply 
the  skin.  It  communicates  with  the  posterior  auricular,  the  small  occi- 
pital, and  the  third  cervical  nerves. 

The  small  occipital  nerve,  a  branch  of  the  anterior  division  of  the 
second  cervical  (p.  21),  runs  along  the  posterior  border  of  the  sterno- 
irastoid  and  supplies  the  scalp. 

Occasionally,  though  rarely,  a  cutaneous  branch  of  the  suboccipital 
nerve  is  distributed  to  the  back  of  the  head. 

POINTS  OF  SUR-  Raise  the  aponeurosis  of  the  scalp,  and  observe 
OICAL  INTEBEST.  the  quantity  of  loose  connective  tissue  which 
intervenes  between  it  and  the  pericranium.  This  tissue  never 
contains  fat.  There  are  some  points  of  surgical  interest  con- 
cerning it: — 1.  Its  looseness  accounts  for  the  extensive  effusions 
of  blood  which  one  often  sees  after  injuries  of  the  head.  2.  It 
admits  of  large  flaps  of  the  scalp  being  detached  from  the  skull- 
cap ;  but  these  flaps  rarely  slough,  unless  severely  damaged, 
because  they  carry  their  blood-vessels  with  them.  3.  In  phleg- 
monous  erysipelas  of  the  scalp,  the  connective  tissue  becomes 


6  DUBA    MATER. 

infiltrated  with  pus  and  sloughs ;  hence  the  necessity  of  making 
incisions  :  for  the  scalp  will  not  lose  its  vitality,  and  liberate  the 
sloughs  like  the  skin  of  other  parts  under  similar  conditions, 
because  its  vessels  run  above  the  diseased  tissue,  and  therefore  its 
supply  of  blood  is  not  cut  off. 

LYMPHATICS  OF          The  lymphatics  of  the  scalp  run  for  the  most  part 
THE  SCALP.  backwards  towards  the  occiput ;  a  few  run  towards 

the  root  of  the  zygoma,  where  they  enter  the  lymphatic  glands  in 
those  situations,  respectively.  Here,  therefore,  one  finds  glandular 
enlargements  when  the  scalp  is  diseased. 

To  examine  the  brain  and  its  membranes,  the 

DISSECTION.  «.««••  *i 

skull-cap  must  be  removed  about   halt   an  inch 

above  the  supra-orbital  ridges  in  front,  and  on  a  level  with  the 
occipital  protuberance  behind.  It  is  better  to  saw  only  through 
the  outer  table  of  the  skull,  and  to  break  through  the  inner  with  a 
chisel.  In  this  way  the  dura  mater  and  the  brain  are  less  likely 
to  be  injured.  On  removing  the  skull  we  expose  a  tough  fibrous 
membrane,  the  dura  mater,  which  forms  the  most  external  of  the 
membranes  of  the  brain. 

The  meningeal  arteries  ramify  between  the  skull  and  the  dura 
mater.  We  cannot,  however,  with  the  brain  in  situ,  trace  their 
course,  at  present,  throughout ;  so  their  consideration  must  be 
deferred  until  the  brain  has  been  removed. 

This  membrane    is   so    called   because   it   was 
DUBA  MATER. 

thought  to  give  rise  to  all  the  other  fibrous  mem- 
branes in  the  body.  It  is  a  dense  white  fibrous  membrane,  rough 
on  its  outer  aspect,  where  it  is  more  or  less  adherent  to  the  inner 
surface  of  the  skull,  forming  its  internal  periosteum.  On  its  inner 
surface  it  is  smooth  and  shining,  being  lined  by  the  parietal  layer 
of  the  arachnoid  membrane,  which  most  anatomists  now  describe 
as  constituting  a  part  of  the  dura  mater.  In  consequence,  the 
term  '  subdural  space '  is  now  substituted  for  the  old  one — '  the 
cavity  of  the  arachnoid.'  The  dura  mater  differs  in  its  adhesion 
to  the  subjacent  bones  :  its  adhesion  is  firmest  at  the  sutures, 
the  petrous  portion  of  the  temporal  bone,  the  basilar  process,  the 
body  of  the  sphenoid,  the  cribriform  plate  of  the  ethmoid  bone, 


DUKA    MATER.  7 

the  depressions  for  the  Pacchionian  bodies,  and  at  the  margin  of 
the  foramen  magnum.  Its  remarkably  tough  and  fibrous  structure 
adapts  it  exceedingly  well  to  the  four  purposes  which  it  serves : — 
1 .  It  forms  the  internal  periosteum  of  the  skull.  2.  It  forms,  for 
the  support  of  the  lobes  of  the  brain,  three  partitions — namely,  the 
falx  cerebri,  the  falx  cerebelli,  and  the  tentorium  cerebelli.  3.  It 
forms  the  sinuses  or  venous  canals  which  return  the  blood  from  the 
brain.  4.  It  forms  sheaths  for  the  nerves  as  they  leave  the  skull. 

Of  the  partitions  formed  by  the  dura  mater  for  the  support  of 
the  lobes  of  the  brain,  two  are  vertical,  and  separate,  respectively, 
the  two  hemispheres  of  the  cerebrum,  and  those  of  the  cerebellum  ; 
the  third  slopes  backwards,  and  supports  the  posterior  lobes  of  the 
cerebrum. 

This  partition  is  named,  from  its  resemblance  to 
the  blade  of  a  sickle,  falx  cerebri.  It  is  received 
into  the  longitudinal  fissure,  and  separates  the  two  cerebral  hemi- 
spheres. It  begins  in  a  point  attached  to  the  crista  galli,  and 
gradually  becomes  broader  as  it  extends  backwards.  Its  upper 
edge  is  convex,  and  attached  to  the  median  groove  on  the  inner 
aspect  of  the  vertex  of  the  skull ;  its  lower  margin  is  concave  and 
free,  and  runs  along  the  upper  aspect  of  the  corpus  callosum. 
From  its  base  or  broadest  part  proceeds  the  sloping  partition 

TENTORIUM  named  tentorium  cerebelli.     This  forms  an  arch 

CEREBELLI.  for    the    support   of  the  posterior  lobes   of  the 

cerebrum,  so  that  they  may  not  press  upon  the  cerebellum  beneath. 
Observe  that  the  tentorium  is  attached  to  the  transverse  ridge  of  the 
occipital  bone,  to  the  superior  border  of  the  petrous  portion  of  the 
temporal  bone,  and  to  the  posterior  and  anterior  clinoid  processes 
of  the  sphenoid.  The  small  median  partition  which  separates  the 

FALX  CERE-          lobes  of  the  cerebellum  is  called  the  falx  cerebelli. 
BELLI-  It  is  placed  vertically  in  the  same  plane  with  the  falx 

cerebri,  and  its  point  is  downwards  towards  the  foramen  magnum. 
The  dura  mater  is  supplied  with  nerves  by  the  recurrent  branch 
of  the  fourth  nerve,  by  the  fifth  and  eighth  cranial  nerves.     Fila- 
ments have  likewise  been  traced  into  it  from  the  sympathetic 
system  and  from  the  Orasserian  ganglion. 


8  SINUSES    OF   THE    DUEA    MATER. 

SINUSES  OF  THE          It  is  one  of  the  peculiarities  of  the  cerebral  cir- 
DUBA  MATKB,  dilation,  that  the  blood  is  returned  through  canals 

or  sinuses  formed  by  the  dura  mater.     These  canals  are  produced 
FTG.  2.  by  a  splitting  of  the  dura  mater  into  two 

"•      —     layers  as  shown  in  fig.  2,  where  1  represents 
a  vertical  section  through  the  superior  longi- 
tudinal sinus.     They  are  lined  by  the  same 
smooth  membrane  as  the  rest  of  the  venous 
2/1  system.     Since  their  walls  consist  of  un- 


TO  SHOW  FORMA-      yielding  structure,   and  are  always  on  the 
TION  OF  A  SINUS.  stretch,  it  is  obvious  that  they  are  admir- 

ably adapted  to  resist  the  pressure  of  the  brain.     There  are  fifteen 
of  these  sinuses  ;  five  are  pairs,  and  five  are  single,  as  follows : 

The  five  pairs  of  sinuses  are —  The  five  single  sinuses  are— 

The  lateral.  The  superior  longitudinal. 

The  superior  petrosal.  The  inferior  longitudinal. 

The  inferior  petrosnl.  The  circular. 

The  cavernous.  The  transverse. 

The  occipital.  The  straight. 

The   blood    from    all  these  sinuses  is  eventually  discharged 
through  the  internal  jugular  veins. 

SUPERIOR  LON-          This  runs  along  the  upper  edge  of  the  falx  cere- 
GITUDINAL  SINUS.      bri  (fig.  3).     It  begins  very  small  at  the  crista 
'    0  galli,    gradually  increases    in    size 

in  its  course  backwards,  and  op- 
posite the  internal  protuberance 
of  the  occipital  bone  divides  into 
the  right  and  left  lateral  sinuses, 
the  right  being  generally  the  larger. 
Besides  numerous  veins  from  the 
__  cancellous  texture  of  the  skull-cap, 

the  superior  longitudinal  sinus  re- 

1.  superior  longitudinal  sinus.  ceives  large  veins  from  each  hemi- 

2.  Inferior  longitudinal  sinus. 

3.  straight  sinus.  sphere    of    the    cerebrum.     It    is 

interesting  to   observe   that  these 
veins  run  (as  a  rule)  from  behind  forwards,  contrary  to  the  current 


SUPERIOE   LONGITUDINAL    SINUS.  9 

of  blood  in  the  sinus,  and  that  they  pass  through  the  wall  of  the 
sinus  very  obliquely,  like  the  ureter  into  the  bladder.  The  probable 
object  of  this  oblique  entrance  is  to  prevent  regurgitation  of  blood 
from  the  sinus  into  the  veins  of  the  brain. 

Cut  open  the  superior  longitudinal  sinus  :  observe  that  it  is 
triangular  with  its  base  upwards,  and  that  its  cavity  is  intersected 
in  many  places  by  slender  fibrous  cords,  termed  chordae  Willisii.* 
Their  precise  use  is  not  understood. 

GLANDULE  In  the  neighbourhood  of  the  superior  longitu- 

PACCHIONT.  dinal  sinus,  we  meet  with   small  white  elevated 

granulations,  sometimes  arranged  singly,  sometimes  in  clusters, 
which  are  received  into  the  depressions  on  the  inner  aspect  of  the 
skull-cap.  They  are  termed  glandulce  PacchioniJ  and  are  found 
in  four  situations: — 1.  On  the  outside  of  the  dura  mater;  often 
so  large  as  to  occasion  depressions  in  the  bones.  2.  On  the  surface 
of  the  pia  mater.  3.  In  the  interior  of  the  longitudinal  sinus, 
covered  by  its  lining  membrane.  4.  On  the  posterior  and  antero- 
inferior  parts  of  the  posterior  lobe  of  the  cerebrum. 

They  are  due  to  an  increased  growth  of  the  villi,  which  are  nor- 
mally found  in  the  arachnoid  membrane,  and  make  their  way, 
through  the  dura  mater  or  the  pia  mater,  to  the  different  situations 
in  which  they  are  found.  The  greatest  growth  takes  place  from 
the  visceral  layer,  as  may  be  seen  in  the  dissection  of  the  brain. 
These  bodies  are  not  found  at  birth,  but  usually  commence  their 
growth  about  the  third  year,  and  are  always  found  at  the  seventh 
year,  after  which  they  gradually  increase  as  life  advances. 

The  brain  should  now  be  removed,  and  preserved  in  spirit  for 
future  examination.  Its  anatomy,  with  that  of  its  remaining  mem- 
branes, will  be  described  in  a  subsequent  part  of  this  work. 

The  other  sinuses  should  now  be  examined. 

LATEBAL  These  are  the  two  great  sinuses  through  which 

SINUSES.  all  the  blood  from  the  brain  is  returned  to  the 

jugular  veins.     Their  course  is  well  marked  in  the  dry  skull.     The 

*  So  called  after  Willis,  who   first   described   them   in  his  work,  'De  Cerebri 
Anatome,'  1664. 

t  After  the  Italian  anatomist  who  first  described  them,  in  1705. 


10  SINUSES    OF   THE    DUEA    MATER. 

right  is  usually  the  larger.  Each  commences  at  the  internal 
occipital  protuberance,  and  proceeds  at  first  horizontally  outwards, 
enclosed  between  the  layers  of  the  tentorium,  along  a  groove  in 
the  occipital  bone  and  the  posterior  inferior  angle  of  the  parietal ; 
it  then  descends  along  the  mastoid  portion  of  the  temporal  bone, 
and  again  indenting  the  occipital  bone,  turns  forwards  to  the 
foramen  lacerum  posterius,  and  terminates  in  the  internal  jugular 
vein.* 

INFERIOR  LON-  This  is  of  small  size.     It  runs  in  the  inferior 

OITUDINAL  SINUS.  free  border  of  the  falx  cerebri,  and  terminates  in 
the  straight  sinus  at  the  anterior  margin  of  the  tentorium 
(fig.  3). 

This  may  be  considered  as  the  continuation  of 

STRAIGHT  SINUS.  ~ 

the  preceding.  It  runs  along  the  line  of  junction 
of  the  falx  cerebri  with  the  tentorium  cerebelli,  and  terminates  at 
the  divergence  of  the  two  lateral  sinuses.  It  receives  the  two 
vence  Galeni  (fig.  3),  which  return  the  blood  from  the  lateral 
ventricles  of  the  brain. 

CAYERNOUS  This  is  so  called  because  its  interior  is  inter- 

SINUS.  sected   by   numerous   cords.      It    extends    along 

the  side  of  the  body  of  the  sphenoid  bone,  outside  the  internal 
carotid  artery.  It  receives  the  ophthalmic  vein  which  leaves 
the  orbit  through  the  sphenoidal  fissure  ;  and  it  communicates 
with  the  circular  sinus  which  surrounds  the  pituitary  gland 

(fig-  4). 

This   surrounds  the  pituitary   body   (P   in   the 
CIRCULAR  SINUS.  *\         j  -  u     •*»••     •*!. 

diagram  4),  and  communicates  on  each  side  with 
the  cavernous  sinus. 

PETROSAL  These  lead  from  the  cavernous  to  the  lateral 

SINUSES.  sinuses.     There  are  two  on  each  side.     The  supe- 

rior runs  along  the  upper  border  of  the  pars  petrosa,  in  the  attached 
border  of  the  tentorium  cerebelli ;  the  inferior,  the  larger  of  the 
two,  runs  along  the  suture  between  the  pars  petrosa  and  the  occi- 

*  It  has,  in  some  subjects,  another  outlet,  through  the  foramen  raastoideum,  or  else 
through  the  posterior  condyloid  foramen. 


SINUSES    OF    THE    DUEA    MATER. 


pital  bone,  and  ends  in  the  lateral  sinus  just  before  this  termi- 
nates in  the  internal  jugular  vein. 

TRANSVERSE  This  extends  from  one  inferior  petrosal  to  the 

other,  across  the  basilar  process  of  the  occipital 


SINUS. 

bone. 


FIG.  4. 


Third  nerve  .... 
Fourth  nerve  .  .  . 
Sixth  nerve  .  .  . 
First  branch  of  the 
fifth  .  . 


Superior  petrosal  sinus 
Inferior  petrosal  sinus 


Ophthalmic  vein. 


Carotid  artery. 
Cavernous  sinus. 


DIAGRAM    OF    THE    VENOUS    SINUSES    AT    THE    BASE    OF    THE    SKULL. 


OCCIPITAL 

SINUSES. 


These  are  very  small.  They  commence  around 
the  margin  of  the  foramen  magnum,  run  in  the 
falx  cerebelli,  and  open  into  the  divergence  of  the  lateral 
sinuses.* 

*  The  junction  of  the  several  siimses  opposite  the  spine  of  the  occipital  bone  is 
termed  the  torcular  Herophili,  after  the  celebrated  anatomist  who  first  described  it. 
It  is  a  kind  of  triangular  reservoir,  with  the  base  below,  and  presents  six  openings — 
namely,  that  of  the  superior  longitudinal  sinus,  those  of  the  two  lateral  and  of  the  two 


12  MENINGEAL    AKTEEIES. 

MENINGEAL  These  arteries  ramify  between  the  skull  and  the 

ARTERIES.  dura,  mater.     Their  course  may  be  traced  by  the 

grooves  which  they  make  in  the  bones.  They  are  termed  anterior, 
middle,  and  posterior,  from  the  fossae  in  which  they  ramify. 

The  anterior  meningeal  are  derived  from  the  ethmoidal  branches  of 
the  ophthalmic  artery,  and  supply  the  dura  mater  in  the  neighbourhood 
of  the  ethmoid  bone. 

The  middle  meningeal  are  three  in  number :  the  most  important  is 
the  arteria  meningea  media,  a  branch  of  the  internal  maxillary  artery. 
It  enters  the  skull  through  tbe  foramen  spinosum,  and  divides  into  two 
principal  branches ;  one  runs  in  a  groove  near  the  anterior  border  of  the 
parietal  bone,  the  other  curves  backwards  over  the  temporal  bone,  and 
subsequently  ramifies  on  tbe  parietal  bone.  This  artery  gives  off  a  small 
branch — the  petrosal,  which  enters  the  hiatus  Fallopii  and  anastomoses 
with  the  stylo-mastoid  artery  in  the  aqueeductus  Fallopii ;  and  one  or 
more  anastomosing  branches  which  enter  the  orbit  through  the  sphenoidal 
fissure  to  communicate  with  the  ophthalmic  artery.  It  is  accompanied 
by  two  veins  which  empty  themselves  into  the  internal  maxillary  vein. 
The  arteria  meningea  parva,  which  enters  the  skull  through  the  foramen 
ovale,  and  a  meningeal  branch  from  the  ascending  pharyngeal  artery, 
which  comes  up  through  the  foramen  lacerum  medium,  also  supply  the 
dura  mater  and  bones  of  the  middle  fossa. 

The  posterior  meningeal  come  from  the  occipital  and  the  vertebral 
arteries ;  these  enter  the  skull  through  the  foramen  jugulare  and  the 
foramen  magnum,  respectively. 

The  position  of  the  meningeal  arteries  renders  them  liable  to 
injury  in  fractures  of  the  skull ;  hence  extravasation  of  blood 
between  the  skull  and  dura  mater  is  one  of  the  common  causes  of 
compression  of  the  brain. 

The  student   should  now  examine  the  cranial 
DISSECTION.  -,     ,,       ?  •         • 

nerves  as  they  pass  out  through  the  toramina  in 

the  base  of  the  skull,  and  then  dissect  the  cavernous  sinus. 

EXIT  OF  THE  The  cranial  nerves  proceed  in  pairs  through  the 

CRANIAL  NERVES.      foramina  at  the  base  of  the  skull ;  they  are  named 

occipital,  and  that  of  the  straight  sinus.     The  term  torcular  is  an  incorrect  version  of 
the  original  word  <ra-\V  (a  canal  or  gutter),  employed  by  Herophilus. 


EXIT  OP  THE  CRANIAL  NERVES.  13 

first,  second,  third,  fourth,  &c.,  pairs,  according  to  the  order  of 
succession  from  before  backwards. 

The  first  is  the  olfactory  nerve.  This  cannot  be  seen,  be- 
cause the  olfactory  bulb  has  been  removed  with  the  brain.  From 
the  bulb  proceed  about  twenty  branches,  which  pass  through  the 
foramina  in  the  cribriform  plate  of  the  ethmoid  bone,  and  are 
arranged  in  three  sets — inner,  middle,  and  outer.  The  inner  pass 
to  the  septum  nasi ;  the  middle  to  the  roof  of  the  nose ;  and  the 
outer  to  the  outer  wall  of  the  nose  as  low  as  the  middle  turbinated 
bone. 

The  second  (optic  nerve)  passes  through  the  foramen  opticum 
into  the  orbit  accompanied  by  the  ophthalmic  artery. 

The  third  (motor  oculi)  passes  through  the  dura  mater,  close 
behind  the  anterior  clinoid  process,  traverses  the  outer  wall  of  the 
cavernous  sinus,  and  enters  the  orbit  through  the  sphenoidal  fissure. 
Before  passing  through  the  fissure,  it  divides  into  two  branches, 
an  upper  and  a  lower. 

The  fourth  (patheticus\  a  small  nerve,  passes  through  the 
dura  mater  a  little  behind  the  posterior  clinoid  process.  Like 
the  preceding  nerve,  it  passes  through  the  outer  wall  of  the  cavern- 
ous sinus,  and  then  runs  forward  through  the  sphenoidal  fissure. 
Here,  it  lies  above  the  third  nerve,  and  is  finally  distributed  to 
the  superior  oblique  muscle. 

The  fifth  (trifacial  nerve}  passes  through  an  aperture  in  the 
dura  mater  beneath  the  tentorium  cerebelli,  just  above  the  point 
of  the  petrous  portion  of  the  temporal  bone.  It  is  formed  of  two 
parts — a  larger  or  sensory  root,  and  a  smaller  or  motor.  Upon  its 
larger  or  sensory  root  is  developed  a  large  ganglion,  the  Gasserian 
ganglion.  From  this  ganglion  proceed  the  three  primary  divi- 
sions of  the  nerve — the  ophthalmic,  which  passes  through  the 
outer  wall  of  the  cavernous  sinus,  and  subsequently  enters  the 
orbit  through  the  sphenoidal  fissure ;  *  the  superior  maxillary, 

*  While  the  nerve  is  in  the  cavernous  sinus  it  receives  filaments  of  communication 
from  the  cavernous  plexus,  and  also  sends  back  a  branch  to  supply  the  tentorium 
cerebelli  (Arnold).  The  ophthalmic  nerve  is  frequently  very  intimately  connected 
with  a  branch  from  the  fourth  nerve. 


14 


EXIT  OF  THE  CRANIAL  NERVES. 


which  passes  through  the  foramen  rotundum ;  and  the  inferior 
maxillary ,  which  passes  through  the  foramen  ovale.  The  smaller 
root  of  the  fifth  lies  beneath  the  ganglion,  with  which  it  has  no 


Olfactory  bulb     .    . 


Optic  nerve     .  . 

Third  nerve     .  . 

Fourth  nerve  .  . 

Fifth  nerve     .  . 

Sixth  nerve     .  . 
Seventh  nerve 

Ninth  nerve    .  . 

Eighth  nerve  .  . 


FIG.  5. 


DIAGRAM  OF  THE  EXIT  OF  THE  CRANIAL  KEBVES. 

communication,  and  then  joins  the  inferior  maxillary  division  to 
supply  the  muscles  of  mastication  with  motor  power. 


CAVERNOUS    SINUS.  15 

The  sixth  (abducens)  pierces  the  dura  mater  behind  the  body 
of  the  sphenoid  bone,  which  it  grooves.  It  then  passes  along 
the  inner  wall  of  the  cavernous  sinus,  external  to  the  carotid 
artery,  and  enters  the  orbit  through  the  sphenoidal  fissure,  to 
supply  the  external  rectus.  It  is  connected  with  the  cavernous 
plexus  as  it  passes  along  the  inner  wall  of  the  sinus. 

The  seventh,  consisting  of  ihe  facial  and  auditory  nerves,  passes 
(with  the  auditory  artery)  through  the  meatus  auditorius  internus, 
where  the  two  are  connected  with  each  other  by  small  offsets.  At 
first  the  facial  nerve  lies  internal  to  and  above  the  auditory  ;  but 
at  the  bottom  of  the  auditory  meatus,  the  facial  nerve  leaves  it  to 
traverse  a  tortuous  bony  canal,  the  '  aquseductus  Fallopii ; '  the 
auditory  being  distributed  to  the  internal  ear. 

The  eighth,  consisting  of  the  glosso-pharyngeal,  pneumo- 
gastric  and  spinal  accessory  nerves,  passes  through  the  anterior 
part  of  the  foramen  lacerum  posterius.  These  three  divisions  do 
not  all  pass  through  the  same  tube  of  the  dura  mater.  The 
glosso-pharyngeal  has  a  separate  tube,  anterior  to  the  other  two, 
which  have  a  common  one. 

The  ninth,  or  hypoglossal  nerve,  passes  through  the  anterior 
condyloid  foramen  in  two  fasciculi,  which  unite  external  to  the 
skull. 

We  must  now  examine  the  cavernous  sinus,  and 
DISSECTIOH.  ,,  ,  .  ,  ,  .  ,.  ., 

the  nerves  which   course  along   its  walls  to  the 

orbit — namely,  the  third,  the  fourth,  the  ophthalmic  division  of 
the  fifth  and  the  sixth  nerves. 

CAYEKNOUS  This  sinus  (fig.  4)  lies  by  the  side  of  the  body 

SINUS.  of  the  sphenoid  bone.     In  front  it  receives  the 

ophthalmic  vein,  which  passes  backwards  through  the  sphenoidal 
fissure  ;  while  posteriorly  it  divides  into  the  superior  and  inferior 
petrosal  sinuses,  which  have  been  already  described  ;  on  the  inner 
side  it  communicates  with  the  circular  sinus,  which  surrounds  the 
pituitary  body  (P  in  the  diagram  4).  The  interior  of  the  sinus 
is  remarkable  for  the  numerous  fine  bands  of  tissue  which  inter- 
lace in  all  directions. 

In  the  outer  wall  of  the  cavernous  sinus  we  trace,  from  above 


16  CAVERNOUS    SINUS. 

downwards,  the  third  nerve,  the  fourth,  and  the  ophthalmic  divi- 
sion of  the  fifth,  in  their  course  to  the  orbit.  On  its  inner  wall, 
are  situated  the  internal  carotid  artery  with  the  sixth  nerve  below 
and  to  its  outer  side.  These  structures  are  not  actually  within 
the  sinus  so  as  to  be  bathed  by  the  blood,  for  they  are  separated 
from  it  by  the  lining  membrane  of  the  sinus. 

KEIATIVE  Posi-  These  nerves  should  be  traced  from  the  cavernous 
TIONS  OF  NEBVES  sinus,  forwards,  so  as  to  see  how  they  alter  their 
IN  SPHENOIDAL  relative  positions  before  entering  the  sphenoidal  fissure, 
FISSUEE.  a,nd,  again,  in  their  passage  through  it. 

Just  before  entering  the  sphenoidal  fissure,  the  fourth  nerve  (on  its 
way  to  the  orbital  surface  of  the  superior  oblique)  gets  above  the  third, 
which  here  divides  into  an  upper  and  a  lower  branch  (both  proceeding 
to  the  ocular  surface  of  the  muscles  they  supply) ;  lower  still,  we  have 
the  frontal,  lacrymal,  and  nasal  divisions  of  the  ophthalmic  •  lowest  of 
all  is  the  sixth  nerve  on  its  way  to  the  external  rectus. 

In  their  passage  through  the  sphenoidal  fissure,  we  find  that  the 
fourth  nerve,  the  frontal  and  lacrymal  branches  of  the  ophthalmic,  lie  at 
the  top,  on  the  same  level,  and  in  the  above  order  from  within  outwards  : 
thus  they  enter  the  orbit  above  the  muscles.  Lower,  and  in  the  follow- 
ing order  from  above  downwards,  come  the  upper  division  of  the  third, 
the  nasal  branch  of  the  ophthalmic,  the  lower  division  of  the  third,  and 
the  sixth ;  all  of  which  (with  the  ophthalmic  vein)  enter  the  orbit 
between  the  two  origins  of  the  rectus  externus. 

The  dissector  will  better  remember  the  varying  relations  of  these 
nerves,  when  he  has  learnt  their  respective  destinations. 

CUEVES  OF  THE  After  the  removal  of  the  cavernous  sinus,  a 
CAEOTID  AETEET.  good  view  is  obtained  of  the  curves,  like  the 
letter  S,  made  by  the  carotid  artery  on  the  side  of  the  pituitary 
fossa.  The  vessel  enters  the  cranium  at  the  apex  of  the  petrous 
portion  of  the  temporal  bone,  makes  its  sigmoid  curves,  and  then 
passes  through  the  dura  mater,  between  the  anterior  clinoid  pro- 
cess and  the  optic  nerve,  where  it  gives  off  the  ophthalmic  artery. 
Within  the  cavernous  sinus,  small  branches,  arterice  receptaculi, 
arise  from  the  carotid  and  supply  the  pituitary  body,  and  the 
walls  of  the  sinus. 

A  careful  dissection  would  show  a  plexus  of  sympathetic  nerves 


DISSECTION    OF   THE   NECK.  17 

on  the  carotid  artery,  as  it  lies  by  the  side  of  the  body  of  the 
sphenoid.  This  is  the  CAROTID  PLEXUS.  It  is  connected  by  numerous 
filaments  with  the  sixth  nerve  and  the  Grasserian  ganglion.  Those 
filaments  of  the  sympathetic  seen  on  the  artery  in  the  upper 
part  of  the  cavernous  sinus,  constitute  the  CAVERNOUS  PLEXUS, 
which  is  in  communication  with  the  third,  the  fourth,  and  the 
ophthalmic  division  of  the  fifth  nerves. 


THE    DISSECTION   OF  THE   NECK. 

Make  a  vertical  incision  through  the  skin,  down 
the  middle  of  the  neck  from  the  symphysis  of  the 
lower  jaw  to  the  sternum ;  a  second  along  the  clavicle  to  the 
acromion ;  a  third  along  the  base  of  the  jaw  as  far  as  the  mastoid 
process.  Keflect  the  skin,  and  expose  the  cutaneous  muscle  called 
the  platysma  myoides.  Between  the  platysma  and  the  skin  is  a 
layer  of  adipose  tissue,  called  the  superficial  fascia.  It  varies  in 
thickness  in  different  subjects,  but  is  generally  more  abundant  at 
the  upper  part  of  the  neck,  especially  in  corpulent  individuals,  in 
whom  it  occasions  a  double  chin. 

PIATTSMA  The  platysma  myoides  is  the  thin  cutaneous 

MYOIDES.  muscle    of  the    neck.     It    arises    from    the    sub- 

cutaneous tissue  over  the  pectoralis  major  and  deltoid  muscles;* 
thence  proceeding  obliquely  over  the  clavicle  and  the  side  of  the 
neck,  its  fibres  become  more  closely  aggregated,  and  terminate 
thus: — The  anterior  cross  those  of  the  opposite  platysma,  im- 
mediately below  the  symphysis  of  the  jaw,  and  are  lost  in  the 
skin  of  the  chin ;  the  middle  are  attached  along  the  base  of  the 
jaw ;  the  posterior-  cross  the  masseter  muscle,  and  terminate,  partly 
in  the  subcutaneous  tissue  of  the  cheek,  partly  in  the  muscles  at 
the  corner  of  the  mouth.f 

*  Some  anatomists  describe  it  as  having  a  slender  origin  from  the  clavicle  and  the 
acromion. 

t  Some  of  the  uppermost  fibres  of  this  part  of  the  platysma  take  the  name  of 
musculus  risorius :  this  will  be  described  among  the  muscles  of  the  face. 

C 


18  EXTERNAL  JUGULAR  VEIN. 

The  platysma  forms  a  strong  muscular  defence  for  the  neck. 

It  is  also  a  muscle  of  expression.*     It  is  supplied  with  nerves  by 

the  cervical  plexus,  and  by  the  cervical  branch  of  the  facial  nerve. 

Cut  through  the  platysma  near  the  clavicle  and 

D I  S*>  F  CTION 

turn  it  upwards.  Beneath  it  lies  the  general  in- 
vestment of  the  neck,  called  the  deep  cervical  fascia.  Upon  this 
fascia  we  trace  the  superficial  branches  of  the  cervical  plexus  of 
nerves,  the  external  jugular  vein,  and  a  smaller  vein  in  front, 
called  the  anterior  jugular.  These  superficial  veins  are  so  variable 
in  size  and  course,  that  a  general  description  only  is  applicable. 

EXTERNAL  The  external  jugular  vein  is  formed  within  the 

JUGULAR  VEIN.  substance  of  the  parotid  gland  by  the  junction  of 
the  temporal  and  internal  maxillary  veins.  After  receiving  the 
transverse  facial  and  posterior  auricular  veins,  it  appears  at  the 
lower  border  of  the  gland,  crosses  obliquely  over  the  sterno-mastoid 
muscle  (fig.  6),  to  its  posterior  border,  nearly  as  low  down  as  the 
clavicle,  where  it  passes  through  the  deep  cervical  fascia  and  ter- 
minates in  the  subclavian  vein.  It  is  usually  provided  with  two 
pairs  of  valves.  A  line  drawn  from  the  angle  of  the  jaw  to  the 
middle  of  the  clavicle  would  indicate  its  course.  To  trace  the  vein, 
during  life,  press  upon  it  just  above  the  clavicle ;  but  do  not  be 
surprised  if  you  fail  to  find  it ;  it  is  sometimes  wanting,  and  fre- 
quently is  very  small. 

*  If  the  entire  muscle  be  permanently  contracted  it  may  occasion  wry-neck,  though 
distortion  from  such  a  cause  is  an  exceedingly  rare  occurrence.  A  case  in  point  is 
related  by  Mr.  Gooch  (Chirurg.  Works),  in  which  a  complete  cure  was  effected,  after 
the  failure  of  all  ordinary  means  of  relief,  by  the  division  of  the  platysma  a  little 
below  the  jaw. 

The  platysma  myoides  belongs  to  a  class  of  muscles  called  cutaneous,  from  their 
office  of  moving  the  skin.  There  are  not  many  in  man,  except  upon  the  neck  and  fare, 
and  there  is  a  little  one  (2)almaris  brevis)  in  the  palm  of  the  hand.  To  understand 
their  use  thoroughly  we  must  refer  to  the  lower  orders  of  animals,  in  whom  they  fulfil 
very  important  functions,  by  moving  not  only  the  skin,  but  also  its  appendages.  For 
instance,  by  muscles  of  this  kind  the  hedgehog,  porcupine,  and  animals  of  that  family 
can  roll  themselves  up  and  erect  their  quills :  we  are  all  familiar  with  the  broad 
' panniculus  camosus'  on  the  sides  of  herbivorous  quadrupeds,  which  enables  them  to 
twitch  their  skins,  and  thus  rid  themselves  of  insects.  In  birds,  too,  these 
cutaneous  muscles  are  extremely  numerous,  each  feather  having  appropriate  muscles 
to  move  it. 


ANTEBIOR   JUGULAR   VEIN. 


19 


Near  the  angle  of  the  jaw  the  external  jugular  vein  communi- 
cates by  a  large  branch  with  the  internal  jugular. 

Before  its  termination  the  external  jugular  vein  generally  re- 
ceives the  supra-scapular,  posterior  scapular,  and  other  unnamed 
veins :  a  disposition  very  unfavourable  for  the  surgeon,  because 
there  is  a  confluence  of  veins  immediately  over  the  subclavian 
artery  in  the  place  where  it  is  usually  tied. 

FIG.  6. 


Cervical  branch  of 
facial  n.   .    .    . 


Superficial  cervical 
nerve  .... 

External  jugu- 
lar v 

Anterior  jugu- 
lar v.  ... 


Small  occipital  n. 


Auriculo-paro- 
tidean  n, 

Nervus  acces- 
soriu?. 

Descending 
branch  of  cer- 
vical plexus. 


DIAGRAM    OF   THE    SUPERFICIAL   NEItTES   AND    TKIXS    OF    THE   NECK. 


ANTERIOB 
JUGULAR  VEIN. 


The  anterior  jugular  vein  is  situated  more  in 
the  middle  of  the  neck,  and  is  much  smaller  than 
the  external  jugular.  It  commences  by  small  branches  below  the 
chin,  and  runs  down  the  front  of  the  neck,  nearly  to  the  sternum : 
it  then  curves  outwards,  beneath  the  sterno-mastoid  muscle,  and 
opens  either  into  the  external  jugular  or  the  subclavian  vein.  We 
commonly  meet  with  two  anterior  jugular  veins,  one  on  either 
side ;  immediately  above  the  sternum  they  communicate  by  a 
transverse  branch. 

c  2 


20  CUTANEOUS  NERVES  OF  THE  NECK. 

The  size  of  the  anterior  jugular  vein  is  inversely  proportionate 
to  that  of  the  external  jugular.  When  the  external  jugular  is 
small,  or  terminates  in  the  internal  jugular,  then  the  anterior 
jugular  becomes  an  important  supplemental  vein,  and  attains  con- 
siderable size.  It  is  not  uncommon  to  find  it  a  quarter  of  an  inch 
in  diameter,  and  we  Jiave  seen  it  nearly  half  an  inch.  These 
varieties  should  be  remembered  in  tracheotomy. 

Superficial  lymphatic  glands  are  sometimes  found  near  the 
cutaneous  veins  of  the  neck.  They  are  small,  and  escape  observa- 
tion unless  enlarged  by  disease.  One  or  two  are  situated  over  the 
sterno-mastoid  muscle ;  others,  near  the  mesial  line. 

CUTANEOUS  ^ke  cutaneous  nerves  of  the  neck  are  the  super- 

NERVES  OF  THE  ficial  branches  of  the  cervical  plexus :  the  plexus 
NECK.  itself  cannot  at  present  be  seen.  It  lies  under  the 

sterno-mastoid  muscle,  close  to  the  transverse  processes  of  the  four 
upper  cervical  vertebrae,  and  is  formed  by  the  communications  of 
the  anterior  divisions  of  the  four  upper  cervical  nerves.  -  The 
cutaneous  branches  of  the  plexus  emerge  from  beneath  the  posterior 
border  of  the  sterno-mastoid,  and  take  different  directions.  They 
are  named  thus  (fig.  6)  : 

'Ascending  branches.  .   j  Auriculo-parotideaii. 

( Small  occipital. 

Cutaneous  branches  of  .  Transverse  branch   ....      Superficial  cervical, 
the  cervical  plexus.    ]  /Sternal. 

Descending  branches         .         .         .   J  Clavicular. 
I  lAcrominl. 

The  auriculo-parotidean  n.  comes  from  the  second  and  third  cervical 
nerves,  and  ascends  obliquely  over  the  sterno-mastoid  muscle,  near  the 
external  jugular  vein,  towards  the  parotid  gland.  Near  the  gland  it 
divides  into  two  principal  branches,  of  which  the  anterior  or  facial  branch 
is  distributed  to  the  skin  over  the  parotid  gland,  and  the  side  of  the 
cheek ;  the  posterior,  after  ascending  a  short  distance,  gives  off  an  auri- 
cular branch,  which  ramifies  mainly  upon  the  cranial  aspect  of  the 
cartilage  of  the  ear;  and  a  smaller  branch,  the  mastoid,  which  supplies 
the  skin  over  the  mastoid  process.  Other  filaments  of  this  nerve  commu- 
nicate in  the  substance  of  the  parotid  gland  with  branches  of  the  facial 


CEEVICAL    FASCIA.  21 

The  small  occipital  n.  comes  from  the  second  cervical  nerve.  It  runs 
near  the  posterior  border  of  the  sterno-mastoid  muscle  to  the  occiput, 
where  it  supplies  the  back  of  the  scalp,  and  communicates  with  the  great 
occipital  and  the  posterior  auricular  nerves.  It  also  sends  off  a  branch, 
which  is  distributed  to  the  skin  of  the  temporal  region.  Beneath  the 
sterno-mastoid  this  nerve  commonly  forms  a  loop,  which  embraces  the 
nervus  accessorius,  and  sends  a  branch  to  it. 

The  transverse  branch,  called  the  superficial  cervical  n.,  comes  from 
the  second  and  third  cervical  nerves.  It  passes  forwards  over  the  sterno- 
mastoid  muscle,  and  supplies  the  front  of  the  neck.  Some  of  its  filaments 
ascend  towards  the  jaw,  and  join  the  cervical  branch  of  the  facial  nerve  ; 
other  filaments  descend  and  supply  the  skin  in  front  of  the  neck  as  low 
as  the  sternum. 

The  descetiding  branches  are  derived  from  the  third  and  fourth  cervi- 
cal nerves,  and  divide  into  three  branches,  which  cross  over  the  clavicle, 
and  supply  the  skin  of  the  front  of  the  chest  and  shoulder.  Of  these, 
one,  called  the  sternal,  supplies  the  skin  over  the  upper  part  of  the 
sternum ;  another,  the  clavicular,  passes  over  the  middle  of  the  clavicle, 
and  is  distributed  to  the  skin  over  the  pectoral  muscle,  the  mammary 
gland,  and  the  nipple;  the  third,  named  acromial,  crosses  over  the 
acromion  to  supply  the  skin  of  the  shoulder. 

Reviewing  these  cutaneous  branches  of  the  cervical  plexus,  we 
find  that  they  have  a  very  wide  distribution,  for  they  supply  the 
skin  covering  the  following  parts — viz.,  the  ear,  the  back  of  the 
scalp,  the  side  of  the  cheek,  the  parotid  gland,  the  front  and  side 
of  the  neck,  the  upper  and  front  part  of  the  chest  and  shoulder. 

CEEVICAL  Look  for  this  branch  beneath  the  fascia  near 

BBANCH  OF  THE  the  angle  of  the  jaw  (p.  92).  It  leaves  the 
FACIAL  NERVE.  parotid  gland,  and  divides  into  filaments  which 
curve  forwards  below  the  jaw ;  some  of  these  join  the  transverse 
branch  of  the  cervical  plexus ;  others  supply  the  platysma. 

DEEP  CERVICAL  Now  turn  your  attention  to  the  membranous 
FASCIA.  investment  called  the  deep  cervical  fascia,  which 

encloses  the  several  structures  of  the  neck.  In  some  subjects  the 
fascia  is  very  thin ;  in  others,  with  strong  muscles,  it  is  pro- 
portionally dense  and  resisting.  It  is  always  stronger  in  par- 
ticular situations,  for  the  more  effective  protection  of  the  parts 


22  CERVICAL    FASCIA. 

beneath ;  for  instance,  in  front  of  the  trachea,  in  the  fossa  above 
the  clavicle,  and  below  the  angle  of  the  jaw.  It  not  only  covers 
the  soft  parts  of  the  neck  collectively,  but,  by  its  inflections,  forms 
separate  sheaths  for  the  muscles,  vessels,  and  glands.  It  isolates 
them,  and  keeps  them  in  their  proper  relative  position.  A  length- 
ened description  of  its  numerous  layers  would  be  not  only  extremely 
tedious,  but  unintelligible,  without  considerable  knowledge  of  the 
anatomy  of  the  neck.  We  propose,  therefore,  to  give  only  a 
general  outline  of  the  fascia,  and  of  its  principal  layers,  com- 
mencing from  behind. 

Tracing  it  from  behind,  we  find  that  the  cervical  fascia  (some- 
times called  deep  cervical  or  muscular  fascia  of  the  neck)  is 
attached  to  the  ligamentum  nuchas  and  to  the  spinous  and  trans- 
verse processes  of  the  cervical  vertebrae.  From  these  attachments 
it  passes  forwards  over  the  posterior  triangle  of  the  neck  to  the 
posterior  border  of  the  sterno-mastoid,  where  it  splits  into  two 
layers,  which  invest  that  muscle  and  reunite  at  its  anterior  border. 
It  then  passes  towards  the  mesial  line,  where  it  becomes  continuous 
with  the  corresponding  fascia  of  the  opposite  side.  The  layer 
which  lies  in  front  of  the  sterno-mastoid  is  attached  above  to  the 
base  of  the  inferior  maxilla,  and  passes  over  the  parotid  gland,  to 
the  zygoma,  to  the  mastoid  process,  and  the  superior  curved  line  of 
the  occipital  bone.  Traced  downwards,  we  find  it  attached  to  the 
clavicle  and  to  the  upper  border  of  the  sternum.  In  the  middle  line 
it  is  closely  connected  to  the  hyoid  bone,  and  below  the  thyroid 
body  divides  into  two  layers,  one  being  attached  to  the  front  of  the 
upper  border  of  the  sternum,  the  other  to  the  back  of  the  upper 
border  of  the  same  bone.  Between  these  layers  there  is  a  well- 
marked  interval,  containing  more  or  less  fat,  and  one  or  two  small 
lymphatic  glands.  This  layer  forms  investing  sheaths  for  the 
depressor  muscles  of  the  os  hyoides  and  larynx. 

The  other  layer — viz.,  that  which  passes  beneath  the  sterno- 
mastoid — forms  the  common  sheath  for  the  carotid  artery,  internal 
jugular  vein,  and  the  pneumogastric  nerve,  which  lie  behind 
this  muscle  ;  it  is  continued  behind  the  pharynx  (constituting 
the  pr<xvertebral  fascia}  to  join  the  fascia  of  the  opposite  side. 


CEEVICAL   FASCIA.  23 

Below,  it  is  attached  to  the  first  rib,  to  which  it  binds  down 
the  intermediate  tendon  of  the  omo-hyoid ;  and  still  further 
down  it  is  continuous  in  the  chest  with  the  pericardium.  It 
may,  also,  be  traced  under  the  clavicle  along  the  axillary 
vessels  and  nerves  into  the  axilla.  Above,  it  is  attached  to  the 
angle  of  the  lower  jaw,  from  which  it  extends  backwards  to  the 
styloid  process,  and  forms  the  stylo-maxillary  ligament.  Thence 
it  is  attached  to  the  base  of  the  skull,  the  petrous  portion 
of  the  temporal  bone,  and  the  basilar  process  of  the  occipital 
bone. 

A  correct  knowledge  of  the  attachments  of  the  principal  layers 
of  the  cervical  fascia  is  essential  to  a  right  understanding  of  the 
course  which  pus  takes  when  it  forms  in  the  neck.  For  instance, 
suppose  the  pus  to  be  formed  at  the  lower  part  of  the  neck.  If 
it  be  seated  immediately  under  the  superficial  layer  (which  is 
attached  to  the  clavicle),  it  may  burrow  beneath  the  clavicle  into 
the  axilla.  But  if  it  be  seated  beneath  the  deep  layer  (which  is 
attached  to  the  first  rib),  then  it  becomes  a  more  serious  affair, 
since  the  pus  may  travel  through  the  loose  tissue  by  the  side  of 
the  pharynx,  and  make  its  way  into  the  chest,  where  it  may  burrow 
down  the  anterior  or  the  posterior  mediastinum,  and  burst  into 
the  trachea  or  the  oesophagus. 

Besides  forming  sheaths  for  the  several  structures  of  the  neck, 
there  are  other  purposes  to  which  the  cervical  fascia  is  subservient. 
The  firm  attachment  of  its  layers  to  the  sternum,  the  first  rib,  and 
the  clavicle,  forms  a  fibrous  barrier  at  the  upper  opening  of  the 
chest,  which  supports  the  soft  parts,  and  prevents  their  yielding 
to  the  pressure  of  the  atmosphere  during  inspiration.  Dr.  Allan 
Burns  '  first  pointed  out  this  important  function  of  the  cervical 
fascia,  and  has  recorded  a  case  exemplifying  the  results  of  its 
destruction  by  disease. 

Moreover,  the  great  veins  at  the  root  of  the  neck,  namely,  the 
internal  jugular,  subclavian,  and  innominate,  are  so  closely  united 
by  the  cervical  fascia  to  the  adjacent  bones  and  muscles,  that 

*  '  Surgical  A  natomy  of  the  Head  and  Neck.' 


24  STERNO-CLEIDO-MASTOIDEUS. 

when  divided  they  gape.  They  are,  as  the  French  express  it, 
*  canaliseesj  and  are  therefore  better  able  to  resist  the  pressure  of 
the  atmosphere,  which  tends  to  render  them  flaccid  and  imper- 
vious during  inspiration.  But  this  anatomical  disposition  of  the 
great  veins  makes  them  more  liable  to  the  entrance  of  air  when 
wounded.  Instances  of  death  have  been  recorded,  resulting  from 
the  sudden  entrance  of  air  into  the  veins  during  operations  about 
the  neck,  or  even  the  axilla. 

STERNOCLEIDO-  The  sterno-cleido-mastoideus  arises  by  a  rounded 
MA.STOIDEUS.  tendon  from  the  upper  part  of  the  sternum,  and 

by  fleshy  fibres,  from  the  sternal  third  of  the  clavicle.  It  is 
inserted  by  a  thick  tendon  into  the  mastoid  process,  and  by  a 
thin  aponeurosis  into  about  the  outer  half  of  the  superior  curved 
ridge  of  the  occipital  bone. 

The  sternal  origin  of  the  muscle  is  at  first  separated  from  the 
clavicular  by  a  slight  interval:  subsequently  the  sternal  fibres 
gradually  overlap  the  clavicular.  The  muscle  is  confined  by 'its 
strong  sheath  of  fascia,  in  such  a  manner  that  it  forms  a  slight 
curve,  with  the  convexity  forwards.  Observe  especially  that  its 
front  border  overlaps  the  common  carotid  artery  ;  along  this  border 
we  make  the  incision  in  the  operation  of  tying  the  vessel. 

ACTION  OF  When  both  sterno-mastoids  act  simultaneously 

STERKO-MASTOID.  they  draw  the  head  and  neck  forwards,  and  are 
therefore  especially  concerned  in  raising  the  head  from  the  re- 
cumbent position.  When  one  sterno-mastoid  acts  singly,  it  turns 
the  head  obliquely  towards  the  opposite  shoulder ;  in  this  action 
it  co-operates  with  the  splenius  of  the  other  side.*  On  emergency, 
the  sterno-mastoid  acts  as  a  muscle  of  inspiration,  by  raising  the 
sternum  ;  its  fixed  point  being,  in  this  case,  at  the  head. 

The  sterno-mastoid  is  supplied  by  three  nutrient  arteries — an 

*  The  single  action  of  the  muscle  is  well  seen  when  it  becomes  rigid  and  causes  a 
wry  neck.  Other  means  of  relief  failing,  the  division  of  the  muscle  near  its  origin  is 
sometimes  beneficial  in  curing  the  distortion.  In  deciding  as  to  the  propriety  of  this 
operation,  we  should  be  careful  to  examine  the  condition  of  the  other  muscles,  Itst, 
after  having  divided  the  sterno-mastoid,  we  should  be  disappointed  in  removing  the 
deformity. 


TRIANGLES    OF   THE    NECK.  25 

upper,  a  middle,  and  a  lower.  The  upper  sterno-mastoid  artery,  a 
branch  of  the  occipital,  enters  the  muscle  with  the  n.  accessorius, 
close  to  the  mastoid  process  of  the  temporal  bone ;  the  middle 
mastoid  is  a  branch  of  the  superior  thyroid,  and  enters  the  under 
surface  of  the  muscle,  crossing  over  the  common  carotid  on  a 
level  with  the  thyroid  cartilage ;  the  lower  mastoid  is  a  branch 
of  the  supra-scapular,  and  supplies  the  clavicular  portion  of  the 
muscle,  close  to  its  origin. 

The  sterno-mastoid  is  supplied  with  nerves  by  the  n.  acces- 
sorius, and  by  branches  from  the  deep  cervical  plexus ;  these 
branches  come  from  the  second  and  sometimes  the  third  cervical 
nerves. 

TRIANGLES  OF  Anatomists    avail    themselves   of    the   oblique 

THE  NECK.  direction  of  the  sterno-mastoid  muscle  to  divide 

the  neck  on  each  side  into  two  great  triangles,  an  anterior  and  a 
posterior  (fig.  7).  The  base  of  the  anterior  triangle  is  formed  by 
the  jaw,  its  sides  by  the  mesial  line  and  the  front  border  of  the 
sterno-mastoid.  The  posterior  has  the  clavicle  for  the  base,  while 
the  sides  are  defined  by  the  hind  border  of  the  sterno-mastoid,  and 
the  front  border  of  the  trapezius. 

The  omo-hyoid  muscle,  which  crosses  the  neck  under  the 
sterno-mastoid,  subdivides  these  primary  triangles  into  four  smaller 
ones  (fig.  7),  of  unequal  size :  an  anterior  superior,  an  anterior 
inferior,  a  posterior  superior,  and  a  posterior  inferior.  The 
direction  of  the  omo-hyoid  muscle  renders  their  boundaries  at  once 
obvious. 

CONTENTS  OF  The  fat  and  connective  tissue  must  now  be  care- 

POSTERIOR  fully  removed  from  the  posterior  triangle.     The 

TRIANGLE.  following  muscles  will  be  seen  forming  its  floor, 

viz.,  beginning  from  above,  the  splenius  capitis,  the  levator  anguli 
scapulae,  the  scalenus  medius  and  posticus,  and  a  small  portion  of 
the  serratus  magnus.  This  triangle  is  subdivided  into  two  unequal 
parts  by  the  posterior  belly  of  the  omo-hyoid — an  upper  or  occi- 
pital and  a  lower  or  clavicular.  In  the  occipital  triangle,  besides 
the  muscles  just  mentioned  (with  the  exception  of  the  serratus 
magnus),  are  found  the  superficial  branches  of  the  cervical  plexus, 


26 


NEEVUS  ACCESSOKIUS* 


and,  passing  obliquely  downwards  from  beneath  the  stern  o-mastoid 
is  the  spinal  accessory  nerve,  which  enters  the  under  part  of  the 
trapezius.  The  transversalis  colli  (posterior  scapular)  artery 
and  vein,  and  its  branch  the  superficialis  colli  (which  chiefly 
supplies  the  trapezius),  cross  transversely  outwards  the  lower  part 
of  the  space.  A  chain  of  lymphatic  glands  is  also  found  along  the 
posterior  border  of  the  sterno-mastoid. 


.  7. 


N.  acccssorius  .  . 

Digastricus    .  .  . 

Os  hyoides     .  .  . 

Omo-hyoideus  .  . 


Sterno-mastoid 
muscle  drawn  a  side. 

Splenius  capitis. 


Levator  anguli  sca- 
pulse. 

Scalenus  medius. 


Scalenus  auticus. 


DIAGRAM    OF    TBI ANGLES    OF    THE    NECK. 


The  upper  part  of  the  sterno-mastoid  is  traversed 
ACCESSOEIUS.  obliquely  by  a  large  nerve  called  the  spinal  acces- 

sory or  n.  accessorius.  This  nerve,  one  of  the  three  composing 
the  eighth  pair  of  cerebral  nerves,  arises  from  the  side  of  the 
medulla  oblongata  below  the  pneumogastric  nerve,  and  from  the 
cervical  portion  of  the  spinal  cord  by  a  series  of  filaments  from  the 
lateral  tract  as  low  down  as  the  sixth  cervical  vertebra.  It  ascends 
between  the  ligamentum  denticulatum  and  the  posterior  roots  of 
the  spinal  nerves,  through  the  foramen  magnum  into  the  skull. 


SUPRA-CLAVICULAR   TRIANGLE.  27 

It  consists  of  two  portions,  a  medullary  and  a  spinal,  and  leaves 
the  skull  through  the  foramen  jugulare.  Here  the  medullary 
or  accessory  portion  is  connected  with  the  ganglion  of  the  root 
of  the  pneumogastric  by  several  filaments ;  and  lower  down  it 
again  joins  the  pneumogastric  at  the  ganglion  of  the  trunk, 
below  which  the  two  nerves  become  blended.  The  medullary  and 
spinal  portions  communicate  in  the  foramen  jugulare.  Below  the 
foramen  the  spinal  part  runs  behind  the  internal  jugular  vein, 
then  pierces  obliquely  the  upper  third  of  the  sterno-mastoid,  and 
crosses  the  posterior  triangle  of  the  neck  to  the  under  surface  of 
the  trapezius,  to  which  it  is  distributed.  The  nervus  accessorius 
supplies  also  the  sterno-mastoid,  and,  after  leaving  the  muscle,  is 
joined  by  branches  from  the  second  and  third  cervical  nerves. 
Beneath  the  trapezius  it  forms  a  plexus  with  the  third  and  fourth 
cervical  nerves.  The  upper  mastoid  artery,  a  branch  of  the  occi- 
pital, enters  the  sterno-mastoid  with  the  nerve. 

SUPHA-CIAVICU-  The  supra-clavicular  triangle  is  bounded  below 
LAB  TBIANGLE.  by  the  clavicle,  in  front  by  the  outer  border  of 
the  sterno-mastoid.  and  above  by  the  posterior  portion  of  the  omo- 
hyoid  muscle.  The  area  of  the  triangle  thus  formed  will  vary 
in  proportion  to  the  obliquity  of  the  omo-hyoid  muscle,  and  the 
extent  to  which  the  sterno-mastoid  and  trapezius  are  attached  to 
the  clavicle.  The  depth  of  the  vessels  and  nerves  contained  in 
this  space  depends,  not  only  upon  the  degree  to  which  the  clavicle 
arches  forwards,  but  varies  with  the  elevation  and  depression  of 
the  shoulder. 

Immediately  beneath  the  skin  covering  this  region  we  find  the 
platysma  myoides,  the  descending  branches  of  the  cervical  plexus, 
and  a  layer  of  fascia  which  binds  down  the  omo-hyoid  muscle  to 
the  clavicle.  Beneath  this  is  a  deeper  layer  of  fascia,  which  covers 
the  subclavian  vessels  and  the  brachial  plexus  of  nerves,  and 
descends  with  them  beneath  the  clavicle  into  the  axilla.  Between 
these  two  layers  we  meet  with  more  or  less  fat  and  areolar  tissue, 
and  lymphatic  glands  continuous  with  those  in  the  axilla.  It  will 
be  easily  understood  how  a  collection  of  pus,  originating  in  the 
axilla,  may  ascend  in  front  of  the  vessels  and  point  above  the 


28  ANTERIOR   TRIANGLE. 

clavicle,  or,  vice  versa,  how  matter  formed  in  the  neck  may  travel 
under  the  clavicle  and  point  in  the  axilla. 

Near  the  posterior  border  of  the  sterno-mastoid  muscle  the 
external  jugular  vein  passes  through  both  layers  of  the  fascia,  and 
terminates  in  the  subclavian ;  but  before  its  termination  it  is 
commonly  joined  by  the  supra-scapular,  the  posterior  scapular, 
and  other  unnamed  veins  proceeding  from  the  surrounding 
muscles ;  so  that  there  is  in  this  situation  a  confluence  of  veins, 
which,  when  large  or  distended,  are  exceedingly  embarrassing. 

The  fascia  and  the  glands  should  be  removed, 
DISSECTION" 

and    the    following    objects    carefully    dissected. 

Behind  and  nearly  parallel  with  the  clavicle  is  the  supra-scapular 
(transversalis  humeri)  artery,  a  branch  of  the  thyroid  axis.  A 
little  higher  is  the  transversalis  colli,  or  posterior  scapular  (com- 
monly a  branch  of  the  thyroid  axis),  which  crosses  the  lower  part 
of  the  neck  towards  the  posterior  superior  angle  of  the  scapula. 
Both  these  arteries,  the  last  particularly,  are  very  irregular  in 
respect  to  their  origin.  Search  for  the  outer  border  of  the  scalenus 
anticus,  which  descends  from  the  transverse  processes  of  the 
cervical  vertebrae  to  the  first  rib :  running  down  longitudinally 
upon  it  is  seen  the  phrenic  nerve.  The  subclavian  vein  lies  upon 
the  first  rib  in  front  of  the  insertion  of  the  anterior  scalene  muscle. 
The  subclavian  artery,  which  appears  a  little  higher  than  the  vein 
behind  the  outer  border  of  the  scalenus  anticus,  must  be  fairly 
exposed,  care  being  taken  to  preserve  the  small  branch  which  pro- 
ceeds from  the  brachial  plexus  to  the  subclavius  muscle.  The  large 
nerves  constituting  the  brachial  plexus  will  be  found  emerging 
between  the  scalenus  anticus  and  medius,  higher  than  the  subcla- 
vian artery,  and  on  a  plane  posterior  to  that  vessel. 

DISSECTION  The  anterior  triangle  must  now  be  dissected. 

OF  THE  ANTERIOR  In  doing  so,  notice,  before  the  deep  cervical  fascia 
TRIANGLE.  jg  removeci?  the  arching  forwards  of  the  anterior 

border  of  the  sterno-mastoid  muscle,  which  is  connected  to  the 
lower  jaw  by  the  fascia,  so  that  the  common  carotid  artery  is  con- 
cealed from  view  before  the  parts  are  disturbed.  Then  examine  the 
flat  muscles  in  front  of  the  neck,  which  pull  down  the  larynx  and 


DEPRESSORS    OP    THE    OS    HTOIDES.  29 

os  hyoides ;  namely,  the  sterno-hyoid,  sterno-thyroid,  omo-hyoid,  and 
thyro-hyoid.*  Kemove  the  fascia  which  covers  them,  disturbing 
them  as  little  as  possible,  and  take  care  of  the  nerves  (branches  of 
the  descendens  noni),  which  enter  their  outer  borders. 

The  sterno-hyoid  arises  from  the  back  part  of 
STERNO-HYOID.        .,  ,  .  ,      .      ,       .. 

the  sternum  and  posterior  sterno-ciavicular  liga- 
ment, and  occasionally  from  the  clavicle  and  cartilage  of  the  first 
rib,  and  is  inserted  into  the  lower  border  of  the  body  of  the 
os  hyoides.  This  is  the  most  superficial  of  the  muscles  in  front  of 
the  neck.  We  cut  in  the  mesial  line  between  these  muscles  in 
laryngotomy. 

ST.KRNO-  The  sterno-thyroid  arises  from  the  back  part  of 

THTEOID.  the  sternum,  below  and  internal  to  the  origin  of 

the  sterno-hyoid,  and  the  cartilage  of  the  first  rib,  and  is  inserted 
into  the  oblique  ridge  on  the  ala  of  the  thyroid  cartilage.  This 
muscle  is  situated  immediately  under,  and  is  much  broader  than, 
the  sterno-hyoid. 

The  two  sterno-hyoid  muscles  converge  as  they  ascend  to  their 
insertions,  and  opposite  the  cricoid  cartilage  and  the  two  or  three 
upper  rings  of  the  trachea  they  are  in  contact  with  one  another. 
The  sterno-thyroid,  however,  diverge  to  their  insertions,  but  are  in 
contact  below,  the  result  of  which  is  that  the  trachea  is  completely 
covered  in  front  by  muscular  fibres. 

The  omo-hyoid  arises  from  the  upper  border 

of  the  scapula,  and  from  the  ligament  over  the 
notch,  and  is  inserted  into  the  lower  border  of  the  body  of  the 
os  hyoides  near  the  great  cornu.  This  muscle  consists  of  two 
fleshy  portions  connected  by  a  tendon.  From  the  scapula  it 
comes  nearly  horizontally  forwards  across  the  lower  part  of  the 
neck,  and  passes  beneath  the  sterno-mastoid,  over  the  sheath  of  the 
great  vessels  of  the  neck ;  then,  changing  its  direction,  it  ascends 
nearly  vertically  close  to  the  outer  border  of  the  sterno-hyoid. 

*  The  sterno-hyoid  and  sterno-thyroid  muscles  often  present  slight  transverse 
tendinous  lines.  These  tendinous  intersections  are  quite  rudimentary  in  man  ;  but  in 
eome  animals  with  long  necks,  e.g.  the  giraffe,  they  are  so  developed  that  each  de- 
pressor muscle  is  composed  of  alternations  of  muscle  and  tendon. 


DEPEESSOES    OF   THE    OS  HYOIDES. 


Thus  the  muscle  does  not  proceed  straight  from  origin  to  insertion, 
but  forms  an  obtuse  angle  beneath  the  sterno-mastoid  muscle. 
The  intermediate  tendon  is  situated  at  the  angle,  and  is  bound 


Occipital  a.     . 

Hyroglossal  n. 
Descendens 
noni  n.   .     . 


2nd  cervical  n.    •  — 


Superior  thy- 
roid a.     . 


3rd  cervical  n.    . 
Communicans 
noni  n.   .    .     . 

Crico- thyroid  m. 

Internal  jugu- 
lar v.  ."  .  . 

Common  caro- 
tid a.  .  .  . 


Digastricus. 

Junction  of  my- 
lo-hyoidei. 

N.  accessorius. 


Pomum  Adami. 


Cricoid  cartilage. 


Isthmus  of  thy- 
roid gland. 


„  Trachea. 


Middle  thy- 
roid v. 


CENTRAL    LIVE    OF    NECK. — COURSE    AND    RELATIONS    OF   COMMON    CAROTID    ARTERY. 

down  to  the  first  rib  and  the  sternum  by  a  process  of  the  deep 
cervical  fascia.  The  object  of  this  peculiar  direction  of  the  omo- 
hyoid  appears  to  be  to  keep  tense  that  part  of  the  cervical  fascia 


DEPRESSORS  OP  THE  OS  HYOIDES.  31 

which  covers  the  apex  of  the  lung,  and  thus  to  resist  atmospheric 
pressure. 

ACTION  OF  THE  The    sterno-hyoid,    sterno-thyroid,    and    omo- 

DEPRESSOR  hyoid  muscles,  co-operate  in  fixing  the  larynx  and 

MUSCLES.  os  hyoides,  e.  g.  in  sucking,  or  they  depress  the 

larynx  after  it  has  been  raised  in  deglutition.  Again,  they  depress 
it  in  the  utterance  of  low  notes.  That  the  larynx  is  raised  or 
depressed  according  to  the  height  of  the  note  may  be  ascertained 
by  placing  the  ringer  upon  it  while  singing  through  an  octave. 

These  depressor  muscles  are  all  supplied  with  nerves  (fig.  8, 
p.  30)  by  the  descendens  noni  (a  branch  of  the  ninth  or  hypo- 
glossal),  and  by  the  communicantes  noni  (branches  of  the  second 
and  third  cervical  nerves).  The  descendens  noni  sends  a  separate 
branch  to  each  belly  of  the  omo-hyoid.  They  are  supplied  with 
blood  by  the  superior  and  inferior  thyroid  arteries. 

The  thyro-hyoid  arises  from  the  oblique  line 
THYRO-HYOID.  *          J 

on  the  ala  of  the  thyroid  cartilage,  and  runs  up  to 

be  inserted  into  the  body  and  half  the  great  cornu  of  the  os  hyoides. 
This  muscle  is  a  continuation  of  the  sterno-thyroid.  It  is  supplied 
by  a  special  branch  from  the  hypoglossal  nerve.  It  covers  the 
thyro-hyoid  membrane  and  the  superior  laryngeal  nerve  and  artery, 
as  they  enter  the  larynx. 

The  stern o-mastoid  muscle  must  now  be  cut 
DISSECTION. 

transversely  through  the  middle,  and  the  two  ends 

turned  upwards  and  downwards,  so  that  they  may  be  replaced  if 
necessary.  This  done,  notice  the  strong  layer  of  fascia  which  lies 
under  the  muscle  and  forms  part  of  its  sheath.  It  is  attached  to 
the  angle  of  the  jaw,  thence  descends  over  the  large  vessels  of  the 
neck,  and  is  firmly  connected  to  the  clavicle  and  first  rib.  This 
fascia  prevents  matter  coming  'to  the  surface,  when  suppuration 
takes  place  by  the  side  of  the  pharynx. 

Remove  the  fascia,  and  clean  the  various  structures  beneath 
the  sterno-mastoid,  taking  care  not  to  cut  away  the  descendens 
noni  and  communicantes  noni  nerves,  which  cross  the  sheath  of 
the  common  carotid.  Dissect  out  the  lymphatic  glands  which  lie 
along  the  sheath  of  the  large  vessels. 


32  COMMON   CAROTID    ARTERY. 

PAETS  EXPOSED          The  objects  exposed  to  view,  when  the  muscle  is 
BENEATH  THE  reflected,  are  very  numerous.  Among  these  the  more 

STEBKO-MASTOID.  important  are :  the  splenius  capitis  and  colli,  the 
posterior  belly  of  the  digastricus,  the  levator  anguli  scapulae,  sca- 
lenus  medius  and  anticus,  omo-hyoid,  sterno-hyoid,  and  sterno- 
thyroid  muscles ;  the  occipital  artery,  the  common  carotid  artery 
and  its  division,  the  internal  jugular  vein,  the  subclavian  artery 
and  the  branches  of  the  first  part  of  its  course,  the  cervical  plexus, 
and  the  lower  cervical  nerves  which  form  the  brachial  plexus; 
the  phrenic,  pneumogastric,  hypoglossal,  and  spinal  accessory 
nerves,  the  descendens  and  communicantes  noni  nerves ;  the  sub- 
clavian vein  and  its  tributaries ;  and  lastly,  a  small  part  of  the 
parotid  gland,  and  the  three  sterno-mastoid  arteries.  On  the 
left  side,  in  addition,  we  find  the  thoracic  duct. 

COURSE  AND  The  common  carotid  arises  on  the  right  side 

EELATIONS  OF  THE  from  the  arteria  innominata  behind  the  upper 
COMMON  CAROTID.  par^  of  ft\e  right  sterno-clavicular  articulation  ; 
on  the  left,  from  the  arch  of  the  aorta.  It  ascends  in  front  of  the 
bodies  of  the  cervical  vertebrae,  by  the  side  of  the  trachea,  thyroid 
gland,  and  larynx,  as  high  as  the 'upper  border  of  the  thyroid 
cartilage,  and  then  divides  into  the  external  and  internal  carotid. 
Thus  a  line  drawn  from  the  sternal  end  of  the  clavicle  to  a  point 
midway  between  the  mastoid  process  and  the  angle  of  the  jaw,  will 
nearly  indicate  its  course.  It  is  contained  in  a  sheath  of  the  deep 
cervical  fascia.  In  the  same  sheath  are  the  internal  jugular  vein 
and  the  pneumogastric  nerve.  The  vein  lies  on  the  outer  side  of, 
and  parallel  with,  the  artery :  the  nerve  lies  behind,  and  between 
the  artery  and  the  vein.  Behind  the  sheath  are  the  sympathetic 
nerve,  the  inferior  thyroid  artery,  and  the  recurrent  laryngeal  nerve. 
Lastly,  along  the  vertebral  column  the  sheath  lies  successively 
upon  the  longus  colli  and  the  rectus  capitis  anticus  major  muscles. 
Owing  to  the  increasing  breadth  of  the  larynx,  the  two  common 
carotid  arteries,  which  at  their  origin  lie  near  together,  are 
separated  by  a  wide  interval  at  their  point  of  division. 

At  the  lower  part  of  the  neck  the  carotid  artery  is  deeply 
seated ;  it  is  covered  by  the  superficial  fascia,  platysma  myoides, 


COMMON   CAEOTID   AETEEY.  33 

deep  fascia,  the  sternal  portion  of  the  sterno-mastoid,  the  sterno- 
hyoid,  and  thyroid  muscles,  and,  on  a  level  with  the  cricoid  carti- 
lage, it  is  crossed  by  the  omo-hyoid.  Above  this  point  the  artery 
becomes  more  superficial,  and  is  covered  by  the  platysma,  the  cer- 
vical fascia,  the  middle  sterno-mastoid  artery,  and  only  slightly 
overlapped  by  the  sterno-mastoid.  Lying  vipon  the  sheath  of  the 
artery,  we  find  the  descendens  noni  joined  by  the  communicantes 
noni  nerves.  The  sheath  is  crossed  by  three  veins  ;  namely,  the 
facial,  the  superior,  and  inferior*  thyroid  veins,  which  empty  them- 
selves into  the  internal  jugular.  This  is  the  general  rule,  and 
especial  attention  should  be  directed  to  it,  because  the  veins  are 
liable  to  be  overlooked  and  injured  in  the  operation  of  tying  the 
carotid.  To  the  inner  side  of  the  artery  we  find  the  trachea,  the 
thyroid  body,  the  recurrent  laryngeal  nerve,  the  inferior  thyroid 
artery,  the  external  laryngeal  nerve,  and  the  inferior  constrictor 
of  the  pharynx. 

It  is  evidently  easier  to  tie  the  common  carotid  above  the 
omo-hyoid  than  below  it.  In  the  higher  operation  we  make  an 
incision  (two  and  a  half  inches  long)  along  the  inner  border  of  the 
sterno-mastoid,  the  centre  of  the  incision  being  opposite  the  cricoid 
cartilage ;  we  cut  through  the  platysma  and  cervical  fascia,  draw 
aside  the  overlapping  edge  of  the  sterno-mastoid,  and  expose  the 
sheath  of  the  vessel.  A  small  opening  is  then  made  on  the  inner 
side  of  the  sheath  large  enough  to  admit  the  aneurysmal  needle, 
and  the  vessel  is  tied,  care  being  taken  not  to  include  the  pneumo- 
gastric  or  descendens  noni  nerves  in  the  ligature. 

In  the  first  part  of  its  course  the  left  carotid 

J.N  WHAT  HE-  •*• 

SPBCTS  THE  LEFT       differs   from   the   right   in   the   following  parti- 

CAKOTID  DIFFERS        culars  : 

FEOM  THE  EIGHT.  lt    jt  arigeg  from  the  ar(jh  of  the  aorta?  ig  there. 

fore  longer  and  deeper  seated  than  the  right,  and  is  covered  by  the 
first  bone  of  the  sternum. 

2.  It  is  crossed  by  the  left  brachio-cephalic  vein. 

*  The  term  'inferior  thyroid'  vein  is  restricted  in  this  manual  to  the  vein  which 
corresponds  to  the  inferior  thyroid  artery. 

D 


34  INTEBNAL  JUGULAR  VEIN. 

3.  It   is    in   close    relation    with    the    oesophagus    and    the 
trachea. 

4.  It  is  in  close  relation  with  the  left  recurrent  nerve. 

5.  It  is  in  close  relation  posteriorly  with  the  thoracic  duct. 

6.  It  is  covered  by  the  thymus  gland  in  early  life. 

The  common  carotid  as  a  rule  gives  off  no  branch  in  its  course ; 
but,  occasionally,  the  middle  sterno-mastoid,  or  even  the  superior 
thyroid,  arises  from  it  prior  to  its  division.  At  its  bifurcation  it 
usually  presents  a  slight  bulbous  enlargement.  This  dilatation  is 
sometimes  so  marked,  that  it  might  be  mistaken  for  an  incipient 
aneurysm.  It  is  necessary  to  know  that  the  carotid  sometimes 
divides  as  low  as  the  level  of  the  cricoid  cartilage,  and  that  not 
unfrequently  the  division  takes  place  as  high  as  the  hyoid  bone.* 

INTEBNAL  The  internal  jugular  vein  is  the  continuation  of 

JUGULAR  VEIN.  the  lateral  sinus,  and  returns  the  blood  from  the 
brain.  Leaving  the  skull  through  the  foramen  jugulare,  where  it 
presents  a  slight  enlargement,  the  vein  descends  on  the  outer  side 
of  the  carotid,  but  in  the  sheath  with  it,  and  joins  the  subclavian 
vein  at  nearly  a  right  angle  to  form  the  brachio-cephalic  or  in- 
'  nominate  vein.  In  its  course  down  the  neck  it  receives  the 
pharyngeal,  occipital,  lingual,  facial,  superior,  and  inferior  thyroid 
veins. 

Previous  to  their  terminations  the  internal  jugular  veins  incline 
somewhat  to  the  right  side  to  meet  the  corresponding  subclavian 
veins ;  thus,  on  the  right  side,  there  is  a  triangular  interval 
between  the  artery  and  vein  in  which  is  seen  the  pneumogastric 
nerve  and  vertebral  artery ;  on  the  left  side  the  vein  slightly 
overlaps  the  artery,  thus  rendering  ligature  of  the  left  carotid 
more  difficult  than  of  the  right.  The  internal  jugular  veins  more- 

*  It  is  important  that  we  should  be  aware  that  the  common  carotids  differ  occa- 
sionally in  their  origin.  Thus  the  right  may  arise  in  common  with  the  left  carotid, 
or  the  right  may  arise  separately  from  the  arch  of  the  aorta,  in  which  case  the  right 
subclayian  is  usually  transposed.  The  left  may  be  given  off  from  the  innominate 
artery  of  the  right  side,  or  it  may  arise  in  common  with  the  left  (-ubclavian,  and  thus 
form  a  left  innominate.  In  transposition  of  the  aorta  there  is  a  left  innominate, 
which  is  given  off  first,  the  right  carotid  and  the  right  subclavian  arising  as  separate 
branches  from  the  arch. 


DESCENDINS   NONI   NERVE.  35 

over  advance  slightly  to  meet  the  subclavian  veins,  so  that  they  lie 
on  a  plane  a  little  anterior  to  their  accompanying  arteries.  A 
little  before  their  termination  the  internal  jugulars  have  a  double 
valve. 

DESCENDENS  The  descendens  noni  (p.  30),  a  branch  of  the 

NONI  AND  COM-  hypoglossal,  runs  down  obliquely  over  the  sheath 
MUNICANTES  NONI  of  foe  carotid  to  supply  the  depressor  muscles  of 
the  os  hyoides.  Trace  the  nerve  upwards  to  see 
that  it  leaves  the  hypoglossal  where  this  nerve  curves  round  the 
occipital  artery.  For  a  short  distance  the  descendens  noni  lies 
within  the  carotid  sheath ;  but,  about  the  level  of  the  os  hyoides, 
it  comes  through  the  sheath,  and  crosses  obliquely  over  the 
carotid,  from  the  outer  to  the  inner  side.  The  descendens  noni 
is  reinforced  by  one  or  more  nerves  termed  communicantes  noni, 
derived  from  the  second  and  third  cervical  nerves.  These  com- 
municating branches  descend  on  the  outer  side  of  the  internal 
jugular  vein,  and  form  generally  two  loops  in  front  of  the  carotid 
sheath,  constituting  a  triangular  plexus  called  the  '  ansa  hypo- 
glossi.'  From  these  loops  the  nerves  proceed  to  the  anterior  and 
posterior  bellies  of  the  omo-hyoid,  to  the  sterno-hyoid.  and  sterno- 
thyroid  muscles.  A  small  branch  may  sometimes  be  traced  pro- 
ceeding from  the  descendens  noni  into  the  chest  to  join  the  cardiac 
and  phrenic  nerves. 

In  some  subjects  the  descendens  noni  seems  to  be  wanting, 
in  which  case  it  will  probably  be  concealed  within,  the  carotid 
sheath  :  when  this  happens  the  reinforcing  loops  from  the  cervical 
nerves  will  be  found  behind  the  internal  jugular  vein.* 

The   thyroid   body  should   now   be   examined. 
DISSECTION.  *  * 

To  expose  it,  reflect  the  sterno-hyoid  and  thyroid 
muscles  from  their  insertions,  so  that  they  can  be  replaced  if 
necessary.  Next  observe  the  lymphatic  glands  of  the  neck,  and 

*  By  many  anatomists  the  descendens  noni  is  regarded  as  the  combination  of 
filaments  from  the  hypoglossal  and  pneumogastric  nerves;  by  some,  it  is  looked  upon 
as  a  branch  of  the  pneumogasfric;  and  lastly,  which  is  most  probable,  it  is  considered 
by  others  to  be  mainly  derived  from  a  branch  which  is  sent  to  the  hypoglossal  from 
the  first  and  second  cervical  nerves. 

D  2 


36  THYROID    BODY. 

lastly  survey  the  objects  in  the  central  line  of  the  neck,  from 
the  jaw  to  the  sternum. 

This  very  vascular  gland-like  body  lies  over  the 
front  and  sides  of  the  upper  part  of  the  trachea, 
and  extends  upwards  on  each  side  of  the  larynx.  It  consists  of 
two  lateral  lobes,  connected  a  little  below  the  cricoid  cartilage  by 
a  tranverse  portion  called  the  isthmus.  Each  lobe  is  conical, 
about  two  inches  in  length,  with  the  base  opposite  the  fifth  or 
sixth  ring  of  the  trachea,  and  the  apex  by  the  side  of  the  thy- 
roid cartilage.  Its  anterior  surface  is  covered  by  the  sterno-hyoid, 
sterno-thyroid,  and  omo-hyoid  muscles ;  its  deep  surface  embraces 
the  sides  of  the  trachea  and  larynx,  and  usually  extends  so  far  back- 
wards as  to  be  in  contact  with  the  pharynx.  Its  external  border 
overlaps,  in  most  cases  partially,  but  sometimes  completely,  the 
common  carotid  artery,  particularly  on  the  right  side ;  and  there 
are  instances  in  which  the  lobe  is  deeply  grooved  by  the  vessel. 

The  isthmus  lies  over  the  second  and  third  rings  of  the  trachea. 
This  portion  of  the  organ  varies  much  in  its  dimensions.  In  some 
instances  there  is  no  transverse  portion.  This  corresponds  with  the 
normal  disposition  in  most  of  the  lower  orders  of  mammalia ;  but 
in  man,  it  is  a  failure  in  the  union  of  the  two  halves  by  which  the 
organ  is  originally  developed.*  Grenerally,  the  vertical  measure- 
ment is  about  half  an  inch.  Between  its  upper  border  and  the 
cricoid  cartilage  is  a  space  about  one-third  of  an  inch  in  extent, 
where  the  trachea  is  free ;  this  space,  therefore,  is  the  more  preferable 
situation  for  tracheotomy.  But  the  vertical  measurement  of  this 
isthmus  is  sometimes  of  very  considerable  length,  so  that  it  has 
been  seen  covering  the  trachea  almost  down  to  the  sternum.f 

*  Concerning  the  development  of  the  lateral  halves  and  central  portion  of  the 
thyroid  body,  see  a  paper  by  Callender  in  the  Proceedings  of  the  Royal  Society,  1867- 

f  From  the  upper  part  of  the  isthmus,  or  from  the  adjacent  border  of  either  lobe, 
most  commonly  the  left,  a  conical  prolongation  of  the  thyroid  body,  called  the  pyramid, 
frequently  ascends  in  front  of  the  crico-thyroid  membrane,  as  high  as  the  pomum 
Adami,  and  is  attached  to  the  body  of  the  os-hyoides  by  fibrous  tissue.  In  some 
subjects  we  may  observe  a  few  muscular  fibres  passing  from  the  os-hyoides  to  the 
pyramid.  This  constitutes  the  levator  glandula  thyroidece  (see  preparation  in 
Museum  of  St.  Earth.  Hosp.,  Patholog.  Series,  No.  14)  of  some  anatomists.  There 


THYROID    BODY.  37 

The  thyroid  body  is  closely  connected,  by  areolar  tissue,  to  the 
sides  of  the  trachea,  to  the  cricoid  and  thyroid  cartilages.  Hence 
it  rises  and  falls  with  the  larynx  in  deglutition. 

The  thyroid  varies  in  size  in  different  individuals  and  at  differ- 
ent periods  of  life.  It  is  relatively  larger  in  the  child  than  the 
adult,  in  the  female  than  the  male.  In  old  age  it  diminishes  in 
size,  becomes  firmer,  and  occasionally  contains  earthy  matter. 

By  far  the  most  notable  considerations  in  respect  to  the 
thyroid  body  are  the  number,  the  large  size,  and  the  free  inoscula- 
tions of  its  blood-vessels.  The  superior  thyroid  arteries  come 
from  the  external  carotid  and  enter  the  front  surface  of  the  apex 
of  each  lobe ;  the  inferior  thyroid  come  from  the  subclavian,  and 
enter  the  under  surface  of  the  base.  An  artery,  called  the  middle 
thyroid  (thyroidea  ima),  is  observed  in  some  subjects  ;  it  is  given 
off  from  the  arteria  innominata,  or  the  arch  of  the  aorta,  and 
ascends  directly  in  front  of  the  trachea  to  the  isthmus. 

Its  veins  are  equally  large,  and  form  a  plexus  upon  it.  The 
superior  and  inferior  thyroid  veins  cross  the  common  carotid,  and 
open  into  the  internal  jugular.  The  middle  thyroid  veins,  two 
in  number,  descend  over  the  front  of  the  trachea,  communicate 
freely  with  each  other,  and  terminate  in  the  left  brachio-cephalic 
vein.  When  you  perform  tracheotomy,  bear  in  mind  the  size  of 
these  middle  thyroid  veins,  and  the  possible  existence  of  a  middle 
thyroid  artery. 

Its  nerves  are  furnished  by  the  laryngeal  branch  of  the  pneumo- 
gastric  and  the  middle  and  inferior  cervical  ganglia  of  the  sympa- 
thetic. They  accompany  the  arteries. 

STRUCTURE  OF  The  thyroid  body  weighs  from  one  to  two  ounces, 

THE  THYROID  and  belongs  to  the  class  of  ductless  glands,  since 

•BODT-  no   excretory   duct  has  been   discovered.      It   is 

invested  by  a  thin   covering  of  dense   connective   tissue   which 

are  instances  in  which  the  pyramid  is  double;  and,  lastly,  we  have  seen  a  considerable 
portion  of  this  thyroid  substance  lying  over  the  crico-thyroid  membrane,  completely 
isolated  from  the  rest  of  the  organ.  These  varieties  deserve  notice,  because  any  one 
portion  of  this  structure  may  become  enlarged  independent  of  the  rest,  and  occasion  a 
bronchocele. 


38  DEEP   CERVICAL   LYMPHATIC    GLANDS. 

penetrates  it,  imperfectly  dividing  it  into  lobes  and  supporting 
the  vessels  as  they  enter  it.  It  consists  of  a  multitude  of  cells, 
which  vary  in  size,  from  -g^-  inch  to  that  of  a  pin's  head,  and  do 
not  communicate  with  each  other.  In  hypertrophy  of  the  gland 
we  sometimes  see  them  as  large  as  a  horsebean,  or  even  larger. 
The  cells  are  oval  and  are  lined  by  a  single  layer  of  endothelial 
cells  resting  upon  a  basement  membrane,  and  contain  a  glairy 
transparent  fluid,  in  which  are  found  a  large  number  of  nuclei  and 
nucleated  cells.  The  arteries  ramify  most  minutely  upon  their 
walls.  Of  its  functions  nothing  is  definitely  known,  but  probably 
it  is  concerned  in  the  elaboration  'of  the  blood.* 

An  enlargement  of  the  thyroid  body  is  termed  a  '  bronchocele.' 
If  the  relation  of  its  lobes  to  the  trachea  and  oesophagus  be  pro- 
perly understood,  it  is  easy  to  predicate  the  consequences  which 
may  result  from  their  enlargement.  The  nature  and  severity  of 
the  symptoms  will  to  a  certain  extent  be  determined  by  the  part 
of  the  organ  affected.  If  the  isthmus  be  enlarged,  difficulty  in 
breathing  will  probably  be  the  prominent  symptom ;  and  an  en- 
largement of  the  left  lobe  is  more  likely  to  produce  a  difficulty  in 
swallowing,  on  account  of  the  inclination  of  the  oesophagus  towards 
the  left  side. 

An  instance  is  related  by  Allan  Burns  in  which  the  isthmus 
was  placed  between  the  trachea  and  the  oesophagus.  It  must  be 
obvious  that  enlargement  of  a  part  so  situated  would  occasion 
great  difficulty  in  swallowing.  I  have  seen  two  cases  in  which 
the  lateral  lobes  projected  so  far  inwards  that  they  completely 
embraced  the  back  of  the  oesophagus. 

Small  lymphatic  glands  are  observed  about  the  thyroid  body, 
especially  in  front  of  the  trachea ;  one  is  often  situated  over  the 
crico-thyroid  membrane.  These  glands,  if  enlarged  by  disease, 
might  be  mistaken  for  a  small  bronchocele. 

DEEP  CERVICAL         In  the  connective  tissue  which  surrounds  the 
LYMPHATIC  great  vessels  of  the  neck,  we  meet  with  a  series 

GLANDS.  of  lymphatic    glands,  called   the   deep   cervical. 

*  The  thyroid  body  is,  primarily,  developed  as  a  pouch  from  the  anterior  wall  of 
the  pharynx;  the  lateral  lobes  are  first  formed,  and  are  subsequently  united  by  the 
isthmus.  W.  Muller,  '  Jenaisch.  Zeitsch.'  1871. 


OENTEAL   LINE   OP   THE   NECK.  39 

They  form  an  uninterrupted  chain  (whence  their  name  glandules 
concatenate),  from  the  base  of  the  skull,  along  the  side  of  the 
neck,  to  the  clavicle,  beneath  which  they  are  continuous  with  the 
thoracic  and  the  axillary  glands.  Some  of  these  glands  lie  anterior 
to  the  common  carotid  artery ;  others,  between  it  and  the  spine. 
This  disposition  explains  the  well-known  fact,  that,  when  these 
glands  are  enlarged,  the  great  vessels  and  nerves  of  the  neck  are 
liable  to  become  imbedded  in  their  substance. 

The  glands  are  particularly  numerous  near  the  division  of  the 
common  carotid,  by  the  side  of  the  pharynx,  and  the  posterior 
belly  of  the  digastricus.  The  lymphatics  connected  with  them 
come  from  all  parts  of  the  head  and  neck.  These  vessels  unite, 
to  form,  on  both  sides  of  the  neck,  one  or  more  absorbent  trunks, 
called  the  jugular.  On  the  left  side  this  jugular  trunk  joins  the 
thoracic  duct,  or  opens  by  a  separate  orifice  into  the  left  subclavian 
vein  :  on  the  right  it  always  opens  into  the  subclavian  vein. 

The  contiguity  of  the  glands  to  the  great  vessels  and  nerves  of 
the  neck  explains  the  symptoms  produced  by  their  enlargement. 
The  tumour  may  be  so  situated  as  to  be  raised  and  depressed  by 
the  pulsation  of  the  carotid,  and  thus  simulate  an  aneurysm.  A 
careful  examination,  however,  will  distinguish  between  an  inher- 
ent'and  a  communicated  pulsation.  By  grasping  the  tumour  we 
become  sensible  that  the  pulsation  does  not  depend  upon  any 
variation  of  its  magnitude,  but  upon  the  impulse  derived  from  the 
artery ;  consequently,  if  the  tumour  be  lifted  from  the  vessel,  all 
feeling  of  pulsation  ceases. 

SURVEY  OF  THE  The  parts  in  the  central  line  of  the  neck  should 
CENTRAL  LINE  OF  now  be  well  studied  (fig.  8,  p.  30).  Beginning 
THE  NECK.  aj.  {.j,je  chin)  we  observe  the  insertions  of  the 

digastric  muscles.  Below  these  is  the  junction,  or  raphe,  of  the 
mylo-hyoid  muscles.  Then  comes  the  os  hyoides.  Below  the 
os  hyoides  is  the  thyro-hyoid  membrane,  attached  above  to  the 
upper  border  of  the  hyoid  bone,  and  below  to  the  thyroid  cartilage. 
Next  is  the  pomum  Adami,  or  projection  of  the  thyroid  cartilage, 
which  is  apparent  between  the  contiguous  borders  of  the  sterno- 
hyoidei.  Below  the  thyroid  cartilage  is  the  cricoid.  These  two 


40  CENTRAL    LINE    OF   THE   NECK. 

cartilages  are  connected  by  the  crico-thyroid  membrane,  across 
which  runs  the  crico-thyroid  artery  to  join  its  fellow.  Below  the 
cricoid  cartilage  is  the  trachea.  This  is  crossed  by  the  isthmus 
of  the  thyroid  body,  and  lower  down  it  recedes  from  the  surface, 
covered  by  the  middle  thyroid  veins. 

Now  the  chief  surgical  interest  lies  just  above,  and  just  below, 
the  cricoid  cartilage.  This  cartilage  can  be  felt  very  plainly  in 
the  living  subject  at  any  age,  no  matter  how  fat.  In  laryngotomy, 
the  crico-thyroid  membrane  is  divided  transversely.  The  mem- 
brane should  be  divided  close  to  the  edge  of  the  cricoid  c.,  for  two 
reasons  :  1.  In  order  to  be  farther  from  the  vocal  cords.  2.  To 
avoid  the  crico-thyroid  artery  which  crosses  the  middle  of  the 
membrane.  If  more  room  be  required,  the  cricoid  cartilage  should 
be  divided  longitudinally. 

In  tracheotomy,  the  trachea  may  be  opened  by  a  perpendicular 
incision,  above  the  isthmus  of  the  thyroid  body,  or  below  it. 
The  operation  above  the  isthmus,  if  there  be  space  enough  for  the 
introduction  of  the  tube,  is  the  easier  and  safer  of  the  two ;  for 
here  the  trachea  is  nearer  to  the  surface,  and  no  large  blood- 
vessels are,  generally  speaking,  in  the  way.  The  space  available 
measures  from  a  quarter  to  half  an  inch;  and  the  isthmus  is  not 
so  firmly  adherent  to  the  trachea  as  to  prevent  its  being  drawn 
downwards  for  a  short  distance.  However,  it  is  right  to  state, 
that  in  one  case  out  of  every  eight  or  ten,  there  is  no  available 
space. 

Tracheotomy  below  the  isthmus  is  neither  an  easy  nor  a  safe 
operation,  for  many  reasons:  1.  The  trachea  recedes  from  the 
surface  as  it  descends,  so  that  just  above  the  sternum  it  is  nearly 
an  inch  and  a  half  from  the  skin.  2.  The  large  middle  thyroid 
veins  are  in  the  way.  3.  A  middle  thyroid  artery  may  run  up  in 
front  of  the  trachea,  direct  from  the  arteria  innominata.  4.  The 
arteria  innominata  itself  lies  sometimes  upon  the  trachea  higher 
than  usual,  and  may,  therefore,  be  in  danger.  5.  The  left  brachio- 
cephalic  vein  in  some  cases  crosses  the  trachea  above  the  edge  of 
the  sternum  instead  of  below  it.  The  celebrated  French  surgeon 
Beclard  used  to  relate  in  his  lectures  the  following  occurrence  : 


SUBMAXILLARY   EEGION.  41 

A  student  had  fallen  into  the  Seine,  and  was  nearly  drowned.  As 
he  was  recovering  very  gradually,  some  kind  friends  attempted  to 
accelerate  the  process  by  making  an  opening  into  the  trachea.  In 
so  doing  they  wounded  the  brachio-cephalic  vein.  Blood  poured 
into  the  trachea,  and  the  result  was  instantly  fatal. 

Whoever  pays  attention  to  this  subject  in  the  dissecting-room 
will  soon  be  convinced  of  the  fact,  that  not  only  large  veins  but 
large  arteries  occasionally  cross  the  crico-thyroid  membrane  as  well 
as  the  trachea,  thus  showing  the  necessity  of  cutting  cautiously 
down  to,  and  fairly  exposing  the  air  tube,  before  we  venture  to 
open  it.* 

DISSECTION  OF  "When  the  platysma  and  the  cervical  fascia  have 

THE  StrBMAxiL-  ^^  remove(j  from  fo^y.  attachment  to  the  jaw, 
LAKY  KEQION,  OR  .  .  i  •  i 

THE  DIGASTRIC          the  most  conspicuous  object  is  the  submaxillary 

TRIANGLE.  gland.     Observe  that  the   fascia  forms   for  it  a 

complete  capsule.  Beneath  the  jaw  are  several  lymphatic  glands, 
from  six  to  ten  in  number,  of  which  some  lie  superficial  to  the 
salivary  gland,  others  beneath  it.  These  glands  receive  the 
lymphatics  of  the  face,  the  tonsils,  and  the  tongue. 

A  little  dissection  will  expose  a  muscle  called  the  digastricus, 
consisting  of  two  distinct  portions  connected  by  a  tendon.  They 
form,  with  the  body  of  the  jaw,  a  triangle,  called  the  digastric, 
of  which  we  propose  to  examine  the  contents.  And  first  of  the 
digastric  muscle  itself. 

The  digastricus  consists  of  two  muscular  bellies 
united  by  an  intermediate  tendon.  It  arises  from 
the  digastric  fossa  of  the  temporal  bone,  passes  obliquely  down- 
wards and  forwards,  and  then  ascends  to  be  inserted  close  to  the 
symphysis  of  the  lower  jaw.  Eaise  the  submaxillary  gland  to 
see  the  intermediate  tendon  of  the  digastricus,  the  angle  which 
it  forms,  and  how  it  is  fastened  by  aponeurosis  to  the  body  and 
greater  cornu  of  the  os  hyoides.  Observe  also  that  this  aponeurosis 

*  It  is  preferable,  after  making  the  first  incision  through  the  skin,  to  lay  aside  the 
sharp  knife  and  to  use  a  blunt  one,  so  that  the  tissues  may  be  torn  rather  than  cut ; 
by  this  proceeding  the  liability  to  hsemorrhage  is  materially  lessened. 


42 


SUBMAXILLART   EEGION. 


is  connected  in  the  mesial  line  with  its  fellow  of  the  opposite  side, 
so  that  a  fibrous  expansion  occupies  the  interval  between  the 
anterior  portions  of  the  digastrici. 

The  chief  action  of  the  digastricus  is  to  depress  the  lower 
jaw.  But  if  the  lower  jaw  be  fixed,  then  the  muscle  raises  the  os 
hyoides,  as  in  deglutition. 

FIG.  9. 


Occipital  a. 


Facial  a. 
Mylo-hyoid  n. 


Snbmental  a. 


Descendens  noni  n.  .    . 
Lingual  a 

Internal  jugular  v. .    . 
Superior  thyroid  a. .    . 


Common  carotid  a  . 


DIGASTRIC    TRIANGLE   AND    CONTENTS. 


The  posterior  belly  of  the  digastricus  is  supplied  by  a  nerve 
from  the  facial ;  the  anterior  belly  by  a  branch  from  the  mylo- 
hyoidean  nerve  (which  comes  from.the  third  division  of  the  fifth 
pair). 


SUBMAXILLARY    REGION.  43 

STYLO-  The  stylo-hyoideus  arises  from  the  middle  of 

HYOIDEUS.  the  styloid  process  of  the  temporal  bone,  and  is 

inserted  into  the  body  of  the  os  hyoides.  This  muscle  runs  close 
along,  but  above,  the  posterior  belly  of  the  digastricus.  Most 
frequently  the  digastric  tendon  runs  through  the  substance  of  it. 
Its  nerve  is  derived  from  the  facial  close  to  its  exit  from  the 
stylo-mastoid  foramen,  in  common  with  the  branch  to  the  posterior 
belly  of  the  digastricus.  Its  action  is  to  raise  and  draw  back  the 
os  hyoides. 

The  digastric  triangle  is  bounded  above  by  the  horizontal 
ramus  of  the  lower  jaw,  parotid  gland,  and  mastoid  process  of  the 
temporal  bone ;  behind  by  the  posterior  belly  of  the  digastricus ; 
and  in  front  by  the  anterior  belly.  The  objects  to  be  examined  in 
this  triangle  are  twelve  in  number,  as  follow  : 

1.  Submaxillary  salivary  gland.  7.  Stylo-maxillary  ligament. 

2.  Facial  vein.  8.  Part  of  the  parotid  gland. 

3.  Facial  artery.  9.  Part  of  the  external  carotid  artery. 

4.  Submental  artery.  10.  Mylo-hyoideus  muscle. 

5.  Mylo-hyoidean  nerve.  11.  Hypoglossal  nerve. 

6.  Submaxillary  lymphatic  glands.  12.  Part  of  the  hyo-glossus  muscle. 

SUBMAXILLARY  In  the  ordinary  position  of  the  head,  the  sub- 

SALIVAEY  GLAND,  maxillary  gland  is  partially  concealed  by  the  jaw, 
but  when  the  head  falls  back  the  gland  is  more  exposed.  It  is 
about  the  size  of  a  chestnut,  and  is  divided  into  several  lobes. 
Its  upper  margin  is  covered  by  the  body  of  the  jaw ;  its  lower 
margin  overlaps  the  side  of  the  os  hyoides.  Its  cutaneous  surface 
is  flat,  being  covered  only  by  the  skin  and  platysma,  but  the  lobes 
on  its  deep  surface  are  irregular,  and  often  continuous  with  those 
of  the  sublingual  gland.  By  raising  the  gland  we  find  that  it  lies 
upon  the  mylo-hyoideus,  the  hyo-glossus,  the  stylo-glossus,  the 
tendon  of  the  digastricus,  and  a  portion  of  the  hypoglossal  nerve, 
seen  above  the  tendon.  The  facial  artery  lies  in  a  groove  on  its 
deeper  surface  and  subsequently  upon  its  upper  border ;  and  it  is 
separated  from  the  parotid  gland,  which  is  situated  behind  it,  by 
the  stylo-maxillary  ligament.  Mark  these  relations  well,  because 


44  SUBMAXILLARY    REGION. 

they  are  of  importance,  as  will  be  presently  explained,  in  tying 
the  lingual  artery. 

The  duct  of  the  gland,  W. harton's  duct*  passes  from  its  under 
surface,  runs  forwards  under  the  mylo-hyoideus  and  upon  the 
hyo-glossus  muscle ;  it  then  passes  beneath  the  gustatory  nerve, 
and  subsequently  runs  between  the  sublingual  gland  and  the 
genio-hyo-glossus,  to  open  into  the  floor  of  the  mouth,  by  the  side 
of  the  fraenum  linguae.  Its  length  is  about  two  inches  ;  its  dimen- 
sions are  not  equal  throughout ;  it  is  dilated  about  the  middle, 
and  contracted  at  the  orifice.  Saliva,  collected  in  the  dilated 
portion,  is  sometimes  spirted  to  a  considerable  distance  out  of  the 
narrow  orifice,  in  consequence  of  the  sudden  contraction  of  the 
neighbouring  muscles. 

In  the  floor  of  the  mouth  there  occasionally  exists  a  cystic 
tumour,  called  a  ranula,  with  semi-transparent  walls,  perceptible 
beneath  the  tongue.  By  some  of  the  older  writers  it  was  looked 
upon  as  an  abnormal  dilatation  of  the  submaxillary  duct.  There 
is,  however,  no  reason  for  believing  this  swelling  (except  very 
rarely)  to  be  connected  with  the  duct.  It  is  rather  a  cyst  formed 
in  the  loose  areolar  tissue  under  the  tongue,  or  is  an  enlargement  of 
one  of  the  small  bursse  which  normally  exist  in  this  situation. 
The  character  of  the  saliva  presents  no  agreement  with  the  fluid 
contained  in  these  cysts,  which  is  thickly  glairy,  like  the  white 
of  an  egg.f 

The  facial  vein  does  not  accompany  the  facial 

FACIAL  VEIN.  ,  .  .    , 

artery,  but  runs  nearly  a  straight  course.  It 
leaves  the  face  at  the  anterior  edge  of  the  masseter  m.,  then  runs 
over  the  submaxillary  gland,  the  digastricus  and  stylo-hyoideus 
and  the  carotid  artery,  to  join  the  internal  jugular.  This  is  the 
rule — but  there  are  frequent  exceptions.  The  principal  point  to 
remember  is,  that  the  vein  runs  superficial  to  the  gland,  and  that 
we  must  be  cautious  in  opening  abscesses  under  the  jaw. 

*  Thorn.  Wharton,  '  Adenographia,  seu  glandularum  totius  corporis  descriptio.' 
12mo.  Amstel.,  1659. 

t  These  sublingual  bursse  were  first  described  by  Fleischmann,  'De  novis  sub 
lingua  bursis,'  Nuremberg,  1841. 


SUBMAXILLAET   REGION.  45 

The  facial  artery  is  the  third  branch  of  the 
external  carotid.  It  runs  tortuously  under  the 
hypoglossal  nerve,  the  posterior  belly  of  the  digastricus  and  stylo- 
hyoideus,  and  beneath  or  through  the  substance  of  the  submaxillary 
gland  to  the  face,  where  it  appears  at  the  anterior  border  of  the 
masseter.  Below  the  jaw  the  facial  gives  off  the  four  following 
branches : 

1.  The  ascending  or  inferior  palatine  artery  runs  up  between  the 
stylo-glossus   and    the   stylo-pharyngeus   m.  to  the  pharynx,  to  which 
and   the   neighbouring  parts   it   gives  branches.     Ascending  as  far  as 
the   levator   palati,    it   divides  into   two  branches ;    one  courses  along 
the  tensor  palati  to  supply  the  soft  palate,  the  other  enters  the  tonsil, 
and  anastomoses  with  the  descending  palatine  and  the  tonsillar  branches 
of  the  ascending  pharyngeal. 

2.  The   tonsillar  runs  up  between  the  internal  pteiygoid  and   the 
stylo-glossus  m.,  then,  perforating  the  superior  constrictor,  it  supplies  the 
tonsil  and  root  of  the  tongue. 

3.  Glandular  branches  to  the  submaxillary  gland  and  side  of  tongue. 

4.  The  submental  arises  from  the  facial  behind   the   submaxillary 
gland,  and  runs  forwards  upon  the  mylo-hyoideus,  beneath  the  inferior 
maxilla,  distributing  branches  in  its  course  to  the  gland  and  the  adjacent 
muscles.     It  then  curves  over  the  bone  and  divides  into  two  branches  : 
a  superficial  one,  which  supplies  the  skin  and  lip ;  and  a  deep  one,  which 
runs  between  the  muscles  and  the  bone,  and  inosculates  with  the  mental 
and  inferior   labial  arteries.      Beneath  the   inferior  maxilla  it  usually 
inosculates  with  the  sublingual  artery. 

MYLO-HYOIDEAN  Look  for  the  mylo-hyoidean  nerve  near  the 
NERVE.  submental  artery.  The  nerve  comes  from  the 

inferior  dental  (before  its  entrance  into  the  dental  foramen), 
and  running  along  a  groove  on  the  inner  side  of  the  inferior 
maxilla,  advances  between  the  bone  and  the  internal  pterygoid 
m.,  to  supply  the  mylo-hyoideus  and  the  anterior  belly  of  the 
digastricus. 

SUBMAXILLARY  ^ne  submaxillary  lymphatic  glands  receive  the 

LYMPHATIC  lymphatics  of  the  face  and  the  tongue.  They  are 

GLANDS.  often  enlarged  in  cancerous  diseases  of  the  tongue 


46  SUBMAXILLART   REGION. 

or  the  lower  lip.  It  should  be  remembered  also  that  there  are 
lymphatic  glands  in  the  mesial  line  below  the  chin. 

MYLO-  The  mylo-hyoideus  arises  from  the  mylo-hyoid 

HTOIDEUS.  ridge  of  the  lower  jaw,  as  far  back  as  the  last 

molar  tooth.  Its  posterior  fibres  are  inserted  into  the  body  of 
the  os  hyoides,  the  anterior  being  attached  to  a  median  tendinous 
line,  termed  the  raphe.  Thus  the  muscles  of  opposite  sides 
form  a  muscular  floor  for  the  mouth.  It  is  supplied  with 
nerves  by  the  mylo-hyoid  branch  of  the  inferior  dental ;  with 
blood  by  the  submental  a.  The  muscles  of  opposite  sides  con- 
jointly elevate  the  os  hyoides  and  the  floor  of  the  mouth — as  in 
deglutition. 

STTLO-MAXIL-  This   is  a  layer   of   the   deep   cervical   fascia, 

LAKY  LIGAMENT.  extending  from  the  angle  of  the  jaw  to  the  styloid 
process.  It  is  a  broad  sheet  of  fascia,  and  separates  the  submaxil- 
lary  gland  from  the  parotid.  It  is  continuous  with  the  fascia 
covering  the  pharynx ;  this  gives  it  a  surgical  interest,  because 
it  prevents  accumulations  of  matter  formed  near  the  tonsils  and 
upper  part  of  the  pharynx  from  coming  to  the  surface. 

The  remaining  objects  seen  in  the  submaxillary  triangle, 
namely,  the  parotid  gland,  the  external  carotid,  the  hypoglossal 
nerve,  and  the  hyo-glossus  muscle,  will  be  described  presently  when 
they  can  be  better  seen.  Your  attention  should  now  be  directed 
to  a  piece  of  surgical  anatomy,  which  will  enable  you  readily  to 
find  and  tie  the  lingual  artery.  It  is  this  : 

A  curved  incision  about  two  inches  in  length  being  made  from 
the  lesser  cornu  along  the  upper  border  of  the  great  cornu  of  the 
os  hyoides,  through  the  skin,  the  platysma,  and  the  cervical  fascia, 
you  will  come  upon  the  lower  edge  of  the  submaxillary  gland. 
Lift  up  the  gland,  which  is  easily  done,  and  underneath  it  you 
will  observe  that  the  tendon  of  the  digastricus  makes  two  sides 
of  a  triangle,  of  which  the  base  is  formed  by  the  hypoglossal  nerve 
crossing  the  hyo-glossus  m.  Within  this  little  triangle,  cut 
transversely  through  the  fibres  of  the  hyo-glossus  :  under  them  is 
the  lingual  artery,  lying  on  the  middle  constrictor.  The  first  time 
you  perform  this  operation  on  the  dead  subject,  you  will  not 


SUBMAXILLARY   REGION.  47 

unlikely  miss  the  artery  and  cut  through  the  middle  constrictor 
into  the  pharynx. 

The  facial  vessels  must  now  be  divided  imme- 
diately below  the  jaw.  Keflect  the  anterior  belly 
of  the  digastricus  from  its  insertion ;  detach  the  mylo-hyoideus 
from  the  middle  line  and  the  os  hyoides,  and  turn  it  over  the  body 
of  the  jaw,  taking  care  not  to  injure  the  muscle  and  structures 
beneath.  The  lower  jaw  must  now  be  sawn  through,  a  little  to 
one  side  of  the  symphysis,  and  the  bone  drawn  upwards  by  hooks. 
The  tongue  should  then  be  drawn  out  of  the  mouth,  and  fastened 
by  hooks.  The  os  hyoides  should  be  drawn  down  by  means  of  hooks, 
so  as  to  put  the  parts  on  the  stretch.  All  this  done,  we  have  to 
make  out,  by  carefully  cleaning  away  the  fat  and  connective  tissue, 
the  following  objects  represented  in  fig.  10,  p.  48  : 

1.  Genio-hyoideus.  6.  Sublingual  gland. 

2.  Hyo-glossus.  7.  Hypoglossal  nerve. 

3.  Stylo-glossus.  8.  Gustatory  nerve. 

4.  Genio-hyo-glossus.  9.  Submaxillary  ganglion. 

5.  Submaxillary  duct.  10.  Lingual  artery. 

GBNIO-  The   genio-hyoideus    arises  from   the   inferior 

HTOIDEUS.  tubercle  behind  the  symphysis  of  the  jaw,  and  is 

inserted  into  the  front  of  the  body  of  the  os  hyoides.  This  round 
muscle  is  situated  •  in  the  mesial  line,  parallel  to  its  fellow.  Its 
nerve  comes  from  the  hypoglossal,  and  its  blood  from  the 
lingual  artery.  Its  action  is  to  draw  the  os  hyoides  forwards  and 
upwards ;  and  if  the  hyoidbone  be  fixed,  it  depresses  the  lower  jaw. 

The   hyo-glossus    arises    from   the   body,   the 
HYO-GLOSSUS.  ,  ,  ,,    ,  ,       .,  ,   . 

greater  and  lesser  cornua  ot  the  os  hyoides,  and  is 

inserted  into  the  posterior  two-thirds  of  the  side  of  the  tongue,  its 
fibres  blending  with  the  stylo-glossus  and  palato-glossus.  It  is  a 
square  and  flat  muscle,  and  its  fibres  ascend  nearly  perpendicularly 
from  origin  to  insertion.*  Its  nerve  comes  from  the  hypoglossal, 
and  its  blood  from  the  lingual  artery.  Its  action  (with  that  of  its 

*  Some  anatomists  ascribe  the  following  names  to  the  different  origins  of  this 
muscle :  that  from  the  body  of  the  hyoid  bone  is  termed  the  basio-glossus,  that  from 
the  greater  cornu  the  cerato-glossus,  and  that  from  the  lesser  cornu  the  chondro-ylossus. 


48 


SUBMAXILLARY   REGION. 


fellow)  is  to  depress  the  tongue.  Observe  the  several  objects  which 
lie  upon  the  hyo-glossus ;  namely,  the  hypoglossal  and  gustatory 
nerves  (which  at  the  anterior  border  form  one  or  more  loops  of 
communication),  the  submaxillary  ganglion,  the  duct  of  the  sub- 
maxillary  gland,  and  the  sublingual  gland.  Beneath  the  hyo- 
glossus  muscle  lie  the  lingual  artery,  part  of  the  middle  constrictor 

FIG.  10. 


Styloid  process    .    . — - 


Glosso-pharyngeal  n. 

Hypoglossal  n. 
Occipital  a.    . 

Submaxillary  gan- 
glion      

Duct  of  submaxillary 
gland. 

Middle  constrictor  m. 

Liugual  a 

Descendens  noni  n.  . 


.  Chorda  tyinpani  n. 
-Gustatory  n. 


MUSCLES,    VESSELS,    AKD    NERVES    OF    THE    TONGUE. 

of  the  pharynx,  part  of  the  genio-hyo-glossus,  the  lingualis  muscle, 
and  the  glosso-pharyngeal  nerve. 

GENIO-  The  genio-hyo-glossus  arises  by  a  tendon  from 

HYO-GLOSSUS.  the  upper  tubercle  behind  the   symphysis  of  the 

lower  jaw,  and  is  inserted  as  follows :  the  lower  fibres  into  the 
body  of  the  os  hyoides ;  the  upper  fibres  into  the  tongue  from  the 
base  to  the  apex.  It  is  the  largest  and  most  important  of  the 
muscles  of  the  tongue.  It  is  fan-shaped,  with  the  apex  attached 


SUBMAXILLART   REGION.  49 

to  the  symphysis  :  thence  its  fibres  radiate  into  the  entire  length 
of  the  tongue.  It  derives  its  nerves  from  the  hypoglossal,  and  its 
blood  from  the  lingual  artery.  Its  action  is  various.  The  posterior 
fibres,  by  raising  the  os-hyoides  and  drawing  forwards  the  base  of 
the  tongue,  protrude  the  tongue  out  of  the  mouth ;  the  anterior 
draw  the  tongue  back  again.  When  every  part  of  the  muscle 
acts,  it  draws  down  the  whole  tongue,  and  is  therefore  one  of  the 
chief  muscles  concerned  in  suction. 

The  stylo-glossus,  a  long  and  slender  muscle, 
arises  from  the  apex  of  the  styloid  process  and 
the  stylo-maxillary  ligament,  and  is  inserted  along  the  side  of  the 
tongue.  It  runs  outside  the  hyo-glossus  nearly  to  the  tip  of  the 
tongue,  and  blends  with  the  fibres  of  this  muscle,  as  well  as  with 
the  palato-glossus.  Its  nerve  comes  from  the  hypoglossal.  Its 
action  is  to  retract  the  tongue. 

HYPOGLOSSAL  The  hypoglossal,  or  ninth  cranial  nerve,  is  the 

NERVE.  motor   nerve  of  the  muscles  of  the  tongue.     It 

arises  (by  several  roots)  from  the  front  of  the  medulla  oblongata 
between  the  pyramid  and  the  olive.  After  leaving  the  skull 
through  the  anterior  condyloid  foramen  (by  two  fasciculi  which 
subsequently  blend),  it  lies  beneath  the  internal  jugular  vein  and 
internal  carotid  artery,  where  it  is  intimately  connected  with  the 
lower  ganglion  of  the  pneumogastric  nerve;  it  then  comes  up 
between  the  artery  and  vein,  and,  immediately  below  the  posterior 
belly  of  the  digastricus,  curves  forwards  over  the  occipital,  the 
internal  and  external  carotid  and  facial,  arteries.  Next  it  crosses 
the  hyo-glossus  muscle,  and  passing  beneath  the  mylo-hyoid, 
divides  into  branches  which  supply  the  following  muscles  ;  namely, 
the  stylo-glossus,  hyo-glossus,  genio-hyo-glossus,  lingualis,  and  the 
genio-hyoideus. 

As  it  curves  round  the  occipital  artery,  the  hypoglossal  nerve 
sends  the  descendens  noni  to  the  depressors  of  the  os  hyoides 
(p.  30).  It  also  sends  a  nerve  to  the  thyro-hyoideus,  which  proceeds 
from  it  where  it  crosses  over  the  external  carotid,  accompanied  by 
the  hyoid  branch  of  the  lingual  artery.  Near  the  anterior  border 


50  SUBMAXILLARY   REGION. 

of  the  hyo-glossus,  it  communicates  by  one  or  more  loops  with  the 
gustatory  nerve.  (Fig.  10.) 

The  hypoglossal  at  its  origin  is  purely  a  motor  nerve.  But 
after  leaving  the  skull,  it  receives  communications  from  the  first 
two  cervical  nerves.  These  communications  are  important  physio- 
logically for  two  reasons :  1 .  They  account  for  the  hypoglossal 
nerve  containing  sensory  fibres.  2.  They  contribute  the  greater 
part  of  the  filaments  of  the  descendens  noni.  It  is  also  connected 
by  small  branches  with  the  pneumogastric  nerve  and  the  superior 
cervical  ganglion  of  the  sympathetic  at  the  base  of  the  skull. 

SUBLINGUAL  The  subliugual  gland  lies  immediately  beneath 

GLAND.  the  mucous  membrane  of  the  floor  of  the  mouth. 

Its  shape  is  oblong,  with  the  long  axis  (about  an  inch  and  a  half) 
directed  from  before  backwards.  It  rests  upon  the  upper  surface 
of  the  mylo-hyoid  muscle,  and  towards  the  mesial  line  it  is  in 
contact  with  the  hyo-glossus  and  the  genio-hyo-glossus. 

The  ducts  of  the  sublingual  gland  (ducts  of  Rivinus*)  vary  in 
number  from  eight  to  twenty.  They  terminate  by  minute  open- 
ings behind  the  orifice  of  the  submaxillary  duct,  along  the  ridge 
felt  upon  the  floor  of  the  mouth.  The  ducts  of  some  of  the  lobes 
terminate  in  the  submaxillary  duct. 

The  duct  of  the  submaxillary  gland  may  now  be  traced  across 
the  hyo-glossus,  and  under  the  gustatory  nerve  to  the  floor  of  the 
mouth. 

LINGUAL  OB  This  nerve  is  a  branch  of  the  inferior  maxillary 

GUSTATORY  or  third  division  of  the  fifth  pair  of  cranial  nerves. 

NERVE.  Emerging  beneath  the  external  pterygoid  m.,  it 

descends  between  the  ramus  of  the  jaw  and  the  internal  ptery- 
goid muscle,  and  comes  forwards  over  the  superior  constrictor  of  the 
pharynx  and  along  the  upper  part  of  the  hyo-glossus,  crossing  at 
an  acute  angle  over  the  duct  of  the  submaxillary  gland.  (Fig.  10.) 
Having  reached  the  under  part  of  the  tongue,  the  nerve  divides  into 
filaments  which  supply  the  papillae  on  its  anterior  three-fourths. 
Beneath  the  external  pterygoid  it  is  joined  at  an  acute  angle  by 
the  chorda  tympani,  and  in  its  course  it  gives  off  some  com- 

*  Aug.  Quirin.  Rivinus,  '  de  Dyspepsia.'     Lips.  1678. 


STJBMAXILLARY   REGION.  51 

municating  branches  to  the  hypoglossal  nerve  near  the  anterior 
border  of  the  hyo-glossus.  It  supplies  also  the  mucous  membrane 
of  the  mouth,  gums,  and  the  sublingual  gland,  and  at  the  apex  of 
the  tongue  the  terminal  branches  of  this  nerve  and  the  hypo- 
glossal  are  connected. 

SUBMAXILLARY  At  the  lower  border  of  the  gustatory  nerve 
GANGLION.  before  it  crosses  the  submaxillary  duct,  you  will 

find  a  small  ganglion,  about  the  size  of  a  pin's  head.  Like  the 
other  ganglia  in  connection  with  the  branches  of  the  fifth  pair,  it 
receives  filaments  of  three  different  kinds — viz.  motor,  sensory, 
and  sympathetic.  Its  motor  root  is  the  chorda  tympani,  which, 
apparently  a  branch  of  the  gustatory,  is  derived  from  the  facial 
nerve.  Its  sensory  roots  proceed  from  the  gustatory;  and  its 
connection  with  the  sympathetic  system  is  established  by  a  branch 
which  comes  from  the  nervi  molles  round  the  facial  artery.  The 
ganglion  supplies  five  or  six  branches  to  the  submaxillary  gland 
and  its  duct.  It  also  supplies  the  mucous  membrane  of  the  floor 
of  the  mouth.* 

LINGUAL  The  lingual  artery  is  generally  the  second 

ARTERY.  branch  of  the  external  carotid.  Curving  slightly 

upwards  from  its  origin,  the  artery  soon  runs  forwards  beneath 
the  posterior  belly  of  the  digastricus,  and  stylo-hyoideus,  and 
then  passes  beneath  the  hyo-glossus  m.,  parallel  to  the  os  hyoides. 
At  the  anterior  edge  of  the  hyo-glossus  it  ascends  to  the  under 
surface  of  the  tongue,  and  is  continued  forwards  to  the  apex  of 
the  tongue  under  the  name  of  ranine.  Under  the  hyo-glossus, 
the  artery  lies  upon  the  middle  constrictor  of  the  pharynx,  and 
the  genio-hyo-glossus ;  in  the  substance  of  the  tongue,  it  lies 
between  the  genio-hyo-glossus  and  the  inferior  lingualis.  The 
curves  made  by  the  artery  are  for  the  purpose  of  allowing  the 
elongation  of  the  tongue.  Its  branches  are  : 

1.  The  hyoid,  a  small  artery  which  runs  along  the  upper  border  of 
the  hyoid  bone,  supplying  the  muscles  and  anastomosing  with  its  fellow. 

*  Meckel  describes  a  small  branch  of  the  ganglion  which  sometimes  passes  for- 
wards to  join  a  branch  of  the  hypoglossal,  on  the  hyoglossus  m.,  and  ends  in  the 
genio-hyo-glossus. 

E  2 


52  EXTERNAL   CAROTID    ARTERY. 

The  nerve  to  the  thyro-hyoid  muscle,  which  is  derived  from  the  hypo- 
glossal,  accompanies  this  artery. 

2.  The  dor  sales  linguae,  two  or  more,  run  under  the  hyo-glossus  to  the 
back  of  the  tongue. 

3.  The  sublingual,  arising  near  the  anterior  border  of  the  hyo-glossus, 
supplies  the  sublingual  gland,  the  mylo-hyoideus,and  the  mucous  membrane 
of  the  mouth  and  gums.     This  artery  generally  gives  off  the  little  artery 
of  the   frsenum  linguae,  which  is   sometimes   wounded  in  cutting   the 
fraenum  in  children  who  are  tongue-tied ;  especially  when  we  neglect  the 
rule  of  pointing  the  scissors  downwards  and  backwards. 

4.  The  ranine  is  the  termination  of  the  lingual  artery.     As  it  runs 
forwards  to  the  tip  of  the  tongue  along  the  outer  side  of  the  genio-hyo- 
glossus,  it  distributes  branches  to  the  tongue,  and  at  the  tip  inosculates 
slightly  with  its  fellow. 

The  lingual  or  ranine  vein  commencing  at  the  tip  of  the 
tongue,  runs  along  its  under  surface  over  the  hyo-glossus,  and 
terminates  in  the  internal  jugular  vein. 

The  best  place  for  finding  and  tying  the  lingual  artery  has 
been  mentioned  (p.  46).  The  rule  laid  down  is  trustworthy  only 
when  the  artery  runs  its  normal  course.  We  have  known  an 
instance  in  which  a  good  anatomist  failed  in  an  attempt  to  tie  the 
lingual  artery,  because  the  vessel  arose  from  the  facial  behind  the 
submaxillary  gland,  and  then  passed  through  the  mylo-hyoideus 
to  reach  the  tongue. 

The  course  and  relations  of  the  external  carotid  artery,  and  its 
branches  in  the  neck,  should  now  be  made  out.  In  preparing  a 
view  of  them,  observe  that  nearly  all  the  veins  lie  in  front  of  their 
corresponding  arteries.  In  removing  the  connective  tissue  and 
•  lymphatic  glands,  the  student  must  take  care  of  the  nerves  and 
other  structures  which  are  liable  to  be  injured. 

COURSE  AND  '^^ie  ex^ernal  carotid  arises  from  the  common 

RELATIONS  OF  THE  carotid  about  the  level  of  the  upper  border  of  the 
EXTEENAL  thyroid  cartilage.  It  ascends  to  the  interval 

CABOTID  ABTEBY.  between  the  ear  and  the  jaw,  and,  at  first,  lies 
beneath  the  sterno-mastoid,  the  cervical  fascia,  the  platysma 
myoides,  and  some  branches  of  the  superficial  nerves.  It  is  next 


BRANCHES  OP  THE  EXTERNAL  CAEOTID.          53 

crossed  by  the  hypoglossal  nerve,  the  facial  and  lingual  veins,  the 
posterior  belly  of  the  digastricus  and  stylo-hyoideus  ;  it  then  enters 
the  parotid  gland,  where  it  lies  beneath  the  facial  nerve  and 
external  jugular  vein,  and  terminates  near  the  neck  of  the  jaw, 
by  dividing  into  the  temporal  and  internal  maxillary  arteries. 

The  external  carotid  is  separated  from  the  internal,  by  the 
stylo-glossus  and  stylo-pharyngeus,  the  giosso-pharyngeal  nerve 
and  the  stylo-hyoid  ligament.  The  superior  laryngeal  nerve  lies 
under  both  vessels. 

Notice  the  relative  position-  which  the  external  and  internal 
carotids  bear  to  each  other.  The  external  lies  at  first  on  the  same 
plane  with,  but  nearer  to  the  side  of  the  pharynx  than  the 
internal.  It  soon,  however,  changes  its  position,  and  crosses 
obliquely  in  front  of  the  internal  to  reach  the  space  between  the 
angle  of  the  jaw  and  the  mastoid  process.  The  internal  carotid 
ascends  perpendicularly  by  the  side  of  the  pharynx  to  the  base  of 
the  skull. 

The  external  carotid  gives  off  the  following  branches  : 

1 .  The  superior  thyroid.  5.  The  posterior  auricular. 

2.  The  lingual.  6.  The  internal  maxillary. 

3.  The  facial.  7.  The  temporal. 

4.  The  occipital.  8.  The  ascending  pharyngeal. 

SUPERIOR  The  superior  thyroid,  the  first  branch  of  the 

THYROID  ARTERY,  external  carotid,  arises  just  below  the  great  cornu 
of  the  os  hyoides.  It  lies  in  the  superior  carotid  triangle,  and 
runs  beneath  the  omo-hyoid,  sterno-hyoid,  and  sterno-thyroid 
muscles  to  the  upper  and  front  surface  of  the  thyroid  body,  in 
which  it  terminates.  Its  branches  are  the  four  following : 

1.  The  hyoid,  a  small  muscular  branch,  runs  horizontally  inwards 
below  the  greater  cornu  of  the  os  hyoides,  and  anastomoses  with  its 
fellow. 

2.  The  superior  laryngeal  branch,  accompanied  by  the  superior  laryn- 
geal nerve,  runs  beneath  the  thyro-hyoid  muscle,  pierces  the  thyro-hyoid 
membrane  (sometimes  the  thyroid  cartilage),  and  supplies  the  muscles 
and  the  mucous  membrane  of  the  larynx. 


54          BRANCHES  OP  THE  EXTERNAL  CAROTID. 

3.  The  middle  sterno-mastoid,  a  small  branch,  variable  as  to  origin, 
descends  over  the  sheath  of  the  carotid  artery  to  the  mastoid  muscle. 

4.  The  crico-thyroid,  an  artery  of  great  interest  in  reference  to  the 
operation  of  laryngotomy,  crosses  the  crico-thyroid  membrane,  and  commu- 
nicates with  a  corresponding  branch  on  the  opposite  side.     (Fig.  8,  p.  30.) 
One  or  two  small  branches  pass  through  the  membrane  to  the  interior  of 
the  larynx.     It  is  important  to  know  that  the  crico-thyroid  artery  often 
varies  in  direction  and  size.     In  most  cases  it  is  small,  and  runs  across 
the  centre  of  the  membrane ;  we  should  therefore  be  least  likely  to  wound 
it  in  laryngotomy,  by  dividing  the  membrane  close  to  the  cricoid  cartilage. 
But  it  is  by  no  means  infrequent  to  find  this  artery  of  considerable  size, 
taking  an  oblique  or  even  a  perpendicular  direction  in  front  of  the  mem- 
brane, and  finally  distributed  to  one  of  the  lobes  of  the  thyroid  body. 
We  have  seen  several  instances  in  which  the  membrane  was  crossed  by 
the  main  trunk  of  the  superior  thyroid.     These  facts  should  establish  the 
practical  rule  in  laryngotomy,  not  to  make  an  opening  into  the  larynx 
until  it  has  been  fairly  exposed. 

Among  the  many  arterial  inosculations  about  the  thyroid  body 
are  two  which  deserve  notice  :  the  one  is  formed  between  the  two 
superior  thyroid  arteries  along  the  upper  border  of  the  isthmus,  the 
other  takes  place  along  the  back  part  of  the  lateral  lobe  between 
the  superior  and  inferior  thyroid  arteries  of  the  same  side. 

The  superior  thyroid  vein  crosses  transversely  the  sheath  of  the 
common  carotid,  and  joins  the  internal  jugular. 
SUPERIOR  *^ne   superior    laryngeal   nerve,    mentioned    as 

LARYNGEAL  accompanying    the  superior  laryngeal   artery,   is 

NEBVE.  given  off  from  the  inferior  ganglion  of  the  pneumo- 

gastric.  It  descends  by  the  side  of  the  pharynx,  behind  both 
carotid  arteries,  and  divides  into  two  branches,  the  internal  and 
external  laryngeal  nerves.  The  internal  branch  enters  the  larynx 
through  the  thyro-hyoid  membrane  accompanied  by  the  superior 
laryngeal  artery,  and  supplies  the  mucous  membrane  of  the 
larynx  with  its  exquisite  sensibility.  Some  of  its  branches  may  be 
traced  upwards  in  the  ary-epiglottidean  fold  to  supply  the  epiglot- 
tis and  base  of  the  tongue ;  others  descend  to  the  rima  glottidis ; 
a  large  branch  passes  down  behind  the  ala  of  the  thyroid  cartilage 


BRANCHES  OF  THE  EXTERNAL  CAROTID.          55 

to  join  the  recurrent  laryngeal  nerve ;  and  a  small  branch  pierces 
the  arytenoideus  to  supply  the  mucous  membrane  beneath  it.  The 
external  branch  accompanies  the  crico-thyroid  artery,  and  after 
distributing  filaments  to  the  pharyngeal  plexus,  supplies  the  inferior 
constrictor  and  the  crico-thyroid  muscles. 

LINGUAL  The  lingual  artery  and  its  branches  have  been 

ABTEET.  described  (p.  51). 

The  facial  artery  and  its  branches  below  the 
jaw  have  also  been  described  (p.  45). 

OCCIPITAL  The  occipital  artery  arises  from  the  posterior 

ARTERY.  part  of  fae  external  carotid,  usually  opposite  the 

facial  artery  and  runs  backwards  along  the  lower  border  of  the 
digastricus  towards  the  mastoid  process.  It  then  passes  under  all 
the  muscles  inserted  into  the  mastoid  process — namely,  the  sterno- 
mastoid,  the  splenius  capitis,  the  trachelo-mastoid,  and  the  digas- 
tric. Arrived  at  the  back  of  the  head,  the  artery  runs  superficial 
to  the  superior  oblique,  the  rectus  capitis  posticus  major  and  the 
complexus,  and  divides  into  wide-spreading  branches  for  the  supply 
of  the  scalp.  In  the  first  part  of  its  course,  the  occipital  artery 
crosses  over  the  internal  carotid  artery,  the  internal  jugular  vein, 
the  pneumo  gastric  and  the  spinal  accessory  nerves,  and  is  itself 
crossed  by  the  hypoglossal  nerve.  It  sends  off  the  six  following 
branches : 

1.  The  superior  sterno-mastoid,  which  enters  the  muscle  with  the 
nervus  accessorius. 

2.  The  auricular  ramifies  on  the  cranial  aspect  of  the  concha. 

3.  The  posterior  meningeal  ascends  with  the  internal  jugular  vein, 
and  enters  the  cranium  through  the  foramen  jugulare  to  supply  the  dura 
mater  of  the  posterior  fossa. 

4.  The  princeps  cervicis,  which  we  shall  see  better  hereafter,  is  a  short 
trunk  which  runs  down  the  back  of  the  neck,  and  divides  into  two  branches 
— a  superficial,  lying  beneath  the  splenius,  and  supplying  also  the  trapezius, 
and  a  deep  branch  lying  under  the  complexus,  and  anastomosing  with 
the  deep  cervical  artery  between  this  muscle  and  the  semi-spinalis  colli. 

5.  The  mastoid   enters  the  foramen  in  the   mastoid  process,  and 
supplies  the  dura  mater. 

6.  The  cranial  branches  supply  the  scalp  on  its  posterior  aspect. 


56          BRANCHES  OP  THE  EXTERNAL  CAROTID. 

The  occipital  vein  usually  terminates  in  the  internal  jugular, 
occasionally  in  the  external  jugular  vein. 

POSTERIOR  Au-  The  posterior  auricular  artery,  the  fifth  branch, 
JUCULAB  AETEET.  js  given  off  from  the  posterior  part  of  the  external 
carotid.  It  arises  above  the  digastricus,  lies  on  the  styloid  process, 
and  under  cover  of  the  parotid  gland  reaches  the  furrow  between 
the  cartilage  of  the  ear  and  the  mastoid  process.  Before  it  reaches 
the  furrow,  it  is  crossed  by  the  facial  nerve,  and  just  beneath  it  is 
the  spinal  accessory.  Above  the  mastoid  process  it  divides  into 
two  branches,  a  posterior  inosculating  with  the  occipital,  and  an 
anterior  communicating  with  the  temporal.  It  supplies  the  back 
of  the  scalp  and  the  cartilage  of  the  ear.  It  gives  off — 

1.  Small  branches  to  the  digastricus,  stylo-hyoid,  and  the  parotid 
gland. 

2.  The  stylo-mastoid,  a  very  constant  little  artery,  which  runs  through 
the  stylo  mastoid  foramen  to  supply  the  mastoid  cells,  the  vestibule,  and 
the  membrana  tympani,  inosculating  with  the  tympanic  branch  of  the 
internal  maxillary. 

3.  The  auricular  branches,  which  supply  both  surfaces  of  the  auricle. 

POSTEBIOE  Au-  The  posterior  auricular  nerve  lies  close  to  the 
KICULAB  NEEVE.  artery  of  the  same  name.  It  is  the  first  branch  of 
the  seventh  or  facial  nerve  after  its  exit  from  the  stylo-mastoid 
foramen.  It  runs  behind  the  ear  and  divides  into  an  auricular 
branch  to  the  retrahens  and  the  attollens  aurem,  and  an  occipital 
branch  to  the  posterior  belly  of  the  occipito-frontalis.  The  nerve 
is  connected  with  the  auriculo-parotidean  branch  of  the  cervical 
plexus,  and  with  the  auricular  branch  of  the  pneumogastric  nerve. 

ASCENDING  This  long  and  straight  branch  arises  about  half 

PHAEYNGEAL  an  inch  above  the  division  of  the  common  carotid. 

ARTEET.  n  ascends  between  the  internal  carotid  and  the 

side  of  the  pharynx  to  the  base  of  the  skull,  lying  upon  the  rectus 
capitis  anticus  major.  It  gives  off  numerous  branches ;  among 
them  are  : 

1.  Small  branches  which  pass  outwards  to  supply  the  anterior  recti 
muscles,  the  superior  cervical  ganglion,  the  pneumogastric  and  hypo- 
glossal  nerves. 


CEEVICAL    PLEXUS.  57 

2.  Pharyngeal  branches,  which  pass  to  the  pharyngeal  muscles ;    one, 
the  largest  of  all,  enters  the  pharynx  above  the  superior  constrictor, 
and  terminates  in  the  soft  palate,  the  Eustachian  tube,  and  the  tonsils. 

3.  A  meningeal  branch,  which  passes  through  the  foramen  lacerum 
posticum,  and  is  distributed  to  the  dura  mater  of  the  occipital  fossa. 

The  examination  of  the  two  remaining  branches  of  the  external 
carotid,  the  internal  maxillary  and  temporal,  must  for  the  present 
be  postponed.  Meanwhile  the  student  should  make  out  the  deep 
cervical  plexus  and  its  branches. 

CERVICAL  This  plexus  is  formed  by  the  anterior  branches 

PLEXUS  OF  of  the  four  upper   cervical   nerves.      It  consists 

NERVES.  of  a  series  of  loop-like  communications,  between 

these  nerves,  close  to  the  transverse  processes  of  the  four  upper 
cervical  vertebrae :  each  nerve  dividing  into  an  ascending  and  a 
descending  branch,  with  the  exception  of  the  first.  The  plexus 
is  situated  behind  the  sterno-mastoid  m.  and  internal  jugular  vein, 
and  lies  in  front  of  the  scalenus  medius  and  the  levator  anguli 
scapulae, 

The  plexus  gives  off  superficial  and  deep  branches.  The  super- 
ficial branches  have  been  already  described  (p.  20). 

The  deep  branches  may  be  divided  into  an  internal  and  an 
external  series. 

INTERNAL  SERIES. —  1.  The  phrenic  arises  from  the  third,  fourth,  and 
fifth  cervical  nerves,  and  passes  through  the  thorax  to  be  distributed  to 
the  diaphragm.  (For  further  course  see  p.  59.) 

2.  The  communicantes  noni  come  from  the  second  and  third  cervical 
nerves,  wind  round  the  internal  jugular  vein,  and  join  the  descendens 
noni  in  front  of  the  carotid  sheath,  forming  the  '  ansa  hypoglossi.'    They 
supply  the  depressor  muscles  of  the  os  hyoides  and  larynx. 

3.  Muscular  branches  to  the  recti  antici,  the   rectus  lateralis,  and 
longus  colli  muscles. 

4.  Branches  which  communicate  with  the  pneumogastric,  hypoglossal, 
and  sympathetic  nerves,  and  one  to  join  the  fifth  cervical. 

EXTERNAL  SERIES. — 1.  One  or  more  branches  to  the  nervus  accesso- 
rius :  firstly  in  the  sterno-mastoid,  then  in  the  occipital  triangle,  and 
lastly  beneath  the  trapezius. 


58  SCALENE    MUSCLES. 

2.  Muscular  branches  to  supply  the  trapezius,  levator  anguli  scapulae, 
scalenus  medius,  and  sterno-mastoid. 

The  clavicle  should  now  be  sawn  through  the 
middle,  and  the  sternal  half  raised  with  the* 
sterno-mastoid  attached,  so  that  the  bone  can  be  replaced,  to  study 
its  relation  to  the  subjacent  parts.  The  scalene  muscles  and  the 
subclavian  artery  throughout  its  whole  course  must  next  be  care- 
fully dissected.  While  this  is  being  done,  the  student  must  be 
careful  not  to  injure  the  branches  of  the  subclavian  artery,  the 
lymphatic  duct  on  the  right,  and  the  thoracic  duct  on  the  left 
side,  the  nerve  to  the  subclavius  m  ,  the  phrenic  nerve,  the  cervical 
and  the  brachial  plexuses  of  nerves,  and  their  small  branches. 
•  SCALENE  The  scalene  muscles,  so  called  from  their  resem- 

MUSCLES.  blance  to  a  scalene  triangle,  extend  from  the  trans- 

verse processes  of  the  cervical  vertebrae  to  the  first  and  second  ribs. 
They  may  be  considered  as  intercostal  muscles,  since  the  trans- 
verse processes  of  the  cervical  vertebrae  are  but  rudimentary  ribs. 
Anatomists  describe  them  as  three  separate  muscles — an  anterior, 
a  middle,  and  a  posterior ;  the  anterior  and  middle  are  attached  to 
the  first  rib,  the  posterior  to  the  second.  In  plan  and  purpose  these 
three  muscles  are  one. 

SCALENUS  The  scalenus  anticus  arises  from  the  anterior 

ANTICUS.  tubercles  of  the  transverse  processes  of  the  third, 

fourth,  fifth,  and  sixth  cervical  vertebrae,  and  is  inserted  by  a  flat 
tendon  into  the  tubercle  on  the  inner  border  of  the  first  rib  in 
front  of  the  groove  for  the  subclavian  artery. 

SCALENUS  The  scalenus  medius  arises  from  the  posterior 

MEDIUS.  tubercles  of  the  transverse  processes  of  all   the 

cervical  vertebrae  except  the  first,  and  is  inserted  into  the  first 
rib  behind  the  scalenus  anticus,  extending,  from  the  tubercle, 
-forwards  for  an  inch  and  a  half. 

SCALENUS  The  scalenus  posticus  arises  from  the  posterior 

POSTICUS.  tubercles  of  the  transverse  processes  of  the  two  or 

three  lowest  cervical  vertebrae,  and  is  inserted  into  the  second  rib 
between  its  tubercle  and  angle,  anterior  to  the  levator  costaa. 


SCALENE    MUSCLES.  59 

The  scalene  muscles  are  important  agents  in  raising  the  thorax, 
in  a  deep  inspiration.  Take  a  deep  breath,  and  you  can  easily  feel 
them  contracting.  They  can  bend  the  cervical  portion  of  the 
spine,  if  their  lower  attachment  be  the  fixed  point,  as  in  rising 
from  the  recumbent  position. 

The  scalenus  anticus  is  just  one  of  those  muscles  about  which 
we  ought  to  know  well  all  that  lies  in  front  of  it,  and  all  that  lies 
behind  it.  In  the  front  of  it  are,  the  clavicle,  the  subclavius,  the 
clavicular  origin  of  the  sterno-mastoid,  the  omo-hyoid,  the  phrenic 
nerve,  the  subclavian  vein,  the  supra-scapular  and  posterior  scapular 
arteries.  Behind  it  are  the  subclavian  artery,  the  five  nerves 
which  form  the  brachial  plexus,  and  the  pleura ;  to  its  inner  side 
is  the  internal  jugular  vein. 

Make  your  finger  familiar  with  the  feel  of  the  tubercle  on  the 
first  rib,  to  which  the  scalenus  anticus  is  attached.  This  tubercle 
is  the  guide  to  the  subclavian  artery,  for  it  enables  you  to  find  the 
outer  edge  of  the  scalenus  anticus,  where  you  must  look  for  the 
vessel.  Is  the  scalenus  anticus  entirely  concealed  from  view  by 
the  sterno-mastoid  or  not  ?  This  will  depend  upon  the  breadth  of 
the  clavicular  attachment  of  the  sterno-mastoid.  As  a  general  rule, 
it  may  be  said  that  the  scalene  muscle  is  concealed  by  the  sterno-mas- 
toid, and  that  consequently,  in  tying  the  subclavian  artery,  it  may 
be  necessary  to  divide  partially  the  clavicular  origin  of  the  muscle. 
The  phrenic  nerve  runs  down  in  front  of  the 
scalenus  anticus,  from  the  outer  to  the  inner 
border.  It  arises  from  the  third,  fourth,  and  fifth  cervical  nerves, 
but  chiefly  from  the  fourth.  It  enters  the  chest  between  the 
subclavian  artery  and  vein,  crosses  in  front  of  the  internal  mam- 
mary artery,  and  continues  its  course  between  the  pericardium 
and  pleura,  in  front  of  the  root  of  the  lung,  to  the  diaphragm, 
which  it  supplies. 

When  the  spinal  cord  is  injured  above  the  fourth  cervical  ver- 
tebra, the  origin  of  the  phrenic  is  implicated ;  therefore  the  dia- 
phragm, as  well  as  the  other  muscles  of  inspiration,  are  paralysed. 
Death  is  the  immediate  result.* 

*  The  phrenic  nerve  is  joined  by  a  filament  from  the  sympathetic,  and  frequently 


60  SUBCLAVIAN  ARTERY. 

COURSE  AND  KELATIONS  OF  THE  SUBCLAVIAN  ARTERIES. 

The  left  subclavian  artery  differs  from  the  right,  not  only  in 
its  origin,  but  in  the  relations  of  the  first  part  of  its  course.  The 
right  should,  therefore,  be  examined  first,  and  then  the  differences 
between  it  and  the  left. 

EIGHT  SUBCLA-          The  right  subclavian  artery  is  one  of  the  two 
VIAN  ARTERY.  great  branches  into  which  the  arteria  innominata 

divides  behind  the  sterno-clavicular  joint.  It  runs  outwards  be- 
hind the  scalenus  anticus,  then  inclines  downwards  over  the  first 
rib,  at  the  outer  border  of  which  it  takes  the  name  of  axillary. 
The  artery  describes  a  curve,  of  which  the  greatest  convexity  is 
between  the  scalene  muscles.  The  height  to  which  the  arch 
ascends  varies.  Grenerally,  it  rises  higher  in  women  than  in  men, 
on  the  right  side  than  on  the  left. 

To  study  its  relations  more  precisely,  the  course  of  the  sub- 
clavian is  divided  into  three  parts  :  1.  The  part  which  intervenes 
between  its  origin  and  the  inner  border  of  the  scalenus  anticus. 
2.  That  which  lies  behind  the  scalenus.  3.  That  which  intervenes 
between  the  outer  border  of  the  scalenus  and  the  outer  border  of 
the  first  rib. 

The  first  portion  of  the  artery  lies  deeply  in  the  neck  and  passes 
upwards  and  outwards  to  the  inner  border  of  the  scalenus  anticus. 
It  is  covered  by  the  skin,  platysma,  superficial  and  deep  fasciae, 
the  sternal  end  of  the  clavicle,  the  sterno-mastoid,  sterno-hyoid, 
and  sterno-thyroid  muscles,  and  a  layer  of  deep  fascia,  continued 
from  the  inner  border  of  the  scalenus  anticus.  It  is  crossed  by 

by  a  filament  from  that  branch  of  the  brachial  plexus  which  supplies  the  subclavius 
muscle.  It  is  important  to  be  aware  that  cases  sometimes  occur  in  which  this  seem- 
ingly insignificant  filament  is  a  branch  of  considerable  size,  and  forms  the  greater 
portion  of  the  phrenic  itself.  We  have  met  with  many  instances  in  which  this  acces- 
sory branch  was  larger  than  the  regular  trunk ;  in  all  of  them  it  crossed  over  the 
subclavian  artery  in  the  third  part  of  its  course,  and  would  probably  have  been  injured 
in  the  operation  of  tying  this  vessel.  That  such  an  accident  has  actually  happened  is 
recorded  by  Bransby  Cooper  in  his  surgical  lectures.  He  speaks  of  having  injured 
tliis  accessory  branch  of  the  phrenic  in  tying  the  subclavian  artery.  The  patient  had 
incessant  spasm  of  the  diaphragm  till  he  died. 


SUBCLAVIAN    AETEEY. 


61 


the  internal  jugular  and  vertebral  veins,  by  the  pneumogastric 
and  phrenic  nerves,  and  by  some  cardiac  filaments  of  the  sym- 
pathetic. Inferiorly  it  rests  upon  the  pleura.  Behind  the  artery 
are  the  recurrent  branch  of  the  pneumogastric,  the  sympathetic 

FIG.  11. 


3rd  cervical  n. 

4th  cervical  n. 
Pneumogas- 
tric n.     .    . 


5tli  cervical  n.      


Brachial  plexus 


Phrenic  n.  .    . 

Line  of  reflec- 
tion of  peri- 
cardium. 


Cervicalis  ascender  s  a. 
Scalenus  anticus. 
Inferior  thyroid  a. 

Snperflcialis  colli  a. 
Phrenic  n. 
Posterior  scapular  a. 

Supra-scapular  a. 
Subclavian  a. 

Superior  intercostal  a. 
Internal  mammary  a. 
Pneumogastric  n. 
Phrenic  n. 


— .Appendix  of  left  auricle. 


nerve,  the  longus  colli,  the  transverse  process  of  the  seventh 
cervical  vertebra  and  the  apex  of  the  lung  covered  with  the  pleura. 
Three  branches  arise  from  this  portion  of  the  subclavian — viz.  the 
vertebral,  internal  mammary,  and  thyroid  axis. 


62  SUBCLAVIAN   ARTERY. 

In  the  second  (the  highest)  part  of  its  course,  the  artery  lies 
between  the  scalene  muscles.  It  is  covered  by  skin,  platysma,  and 
superficial  fascia,  by  the  clavicular  origin  of  the  sterno-mastoid, 
the  deep  cervical  fascia,  and  by  the  scalenus  anticus  and  phrenic 
nerve  which  separate  it  from  the  subclavian  vein.  Behind  the 
artery  is  the  scalenus  medius  ;  above  it  is  the  brachial  plexus ; 
below  it  is  the  pleura.  Only  one  branch,  the  superior  intercostal, 
is  given  off  from  this  part  of  the  artery. 

In  the  third  part  of  its  course,  the  artery  passes  downwards 
and  outwards,  and  lies  in  the  supra-clavicular  triangle  upon  the 
surface  of  the  first  rib.  Here  it  is  covered  by  the  skin,  platysma, 
and  two  layers  of  the  cervical  fascia ;  subsequently  by  the  supra- 
scapular  artery,  the  clavicle,  the  subclavius  muscle,  with  its  nerve ; 
and,  what  is  of  much  more  consequence,  it  is  here  crossed  by  the 
external  jugular  and  (often)  the  supra  and  posterior  scapular  veins  ; 
so  that  there  is  here  a  confluence  of  large  veins  in  front  of  the 
artery.  The  subclavian  vein  is  situated  below  the  artery,  but  on 
a  plane  anterior  to  it.  Below  it  is  the  first  rib,  and  behind  it  the 
scalenus  medius.  Above  the  artery  and  to  its  outer  side,  are  the 
trunk  nerves  of  the  brachial  plexus  and  the  omo-hyoid  m.  One  of 
these  nerves  (the  conjoined  fifth  and  sixth  cervical)  runs  so  nearly 
parallel  with  the  artery,  and  on  a  plane  anterior  to  it,  that  it  is 
quite  possible  to  mistake  the  nerve  for  the  artery,  in  the  operation 
of  tying  it.  We  have  heard  a  hospital  surgeon  of  great  experience 
say,  that  he  had  seen  this  mistake  committed  on  three  separate  occa- 
sions. In  this  part  of  its  course,  the  artery  as  a  rule  gives  off  no 
branches ;  the  most  frequent  exceptions  are  the  posterior  scapular, 
and  supra-scapular. 

LEFT  SUBCLA-  The   left   subclavian  is   the  last  of  the  three 

TIAN  ARTERY.  great  branches  which  arise  from  the  arch  of  the 

aorta.  It  ascends  nearly  vertically  out  of  the  chest,  and  then 
arches  in  front  of  the  apex  of  the  lung  and  pleura  to  reach  the 
inner  border  of  the  scalenus  anticus,  behind  which  it  runs  over 
the  first  rib. 

In  the  first  part  of  its  course,  the  left  subclavian  lies  deeply  in 
the  chest,  near  the  spine.  On  its  left  side  it  is  covered  by  the 


SUBCLAVIAN   ARTERY.  63 

pleura ;  on  its  right  side  are  the  thoracic  duct,  the  oesophagus  and 
the  trachea ;  in  front  are  the  pneumogastric  and  phrenic  nerves, 
the  cardiac  branches  of  the  sympathetic,  the  left  common  carotid, 
and  the  left  lung  covered  with  its  pleura ;  the  left  brachio-cephalic 
vein  crosses  in  front  of  it.  Behind  it  is  the  longus  colli  muscle, 
and  the  inferior  cervical  ganglion. 

At  the  level  of  the  upper  part  of  the  chest,  the  left  sub- 
clavian  arches,  like  the  right,  over  the  apex  of  the  lung,  and 
has  similar  relations — namely,  in  front,  it  is  covered  by  the  sternal 
end  of  the  clavicle,  the  sterno-mastoid,  sterno-hyoid,  and  sterno- 
thyroid  muscles,  and  by  the  internal  jugular  and  vertebral  veins. 

Behind  the  scalenus  anticus,  and  on  the  surface  of  the  first  rib, 
the  relations  of  the  left  subclavian  are  similar  to  those  of  the  right 
(p.  62). 

The  left  subclavian,  then,  differs  from  the  right  only  in  the  first 
part  of  its  course.  Now,  what  are  these  differences  ? 

1 .  The  left  subclavian  comes  direct  from  the  arch  of  the  aorta, 
and  is  therefore  longer,  deeper  in  the  chest,  and  more  vertical 
than  the  right,  which  comes  from  the  arteria  innominata. 

2.  The  left  subclavian  is  in  close  relation  with  the  oesophagus 
and  the  thoracic  duct :  the  right  is  not. 

3.  The  left  subclavian  is  crossed  by  the  left  brachio-cephalic 
vein. 

4.  The   left  subclavian  has  the  phrenic,  pneumogastric,  and 
sympathetic    nerves   nearly  parallel  with  it ;    on  the  right  side, 
these  nerves  cross  the  artery  at  a  nearly  right  angle. 

5.  The  left  subclavian  is  not  embraced  by  the  recurrent  laryn- 
geal  nerve,  like  the  right  subclavian. 

The  thoracic  duct  bears  an  important  relation  to  the  left  sub- 
clavian. It  ascends  from  the  chest  to  the  left  of  the  oesophagus 
and  behind  the  artery  ;  then  arching  behind  the  internal  jugular 
vein  as  high  as  the  seventh  cervical  vertebra,  it  curves  downwards 
and  forwards  to  terminate  in  the  subclavian  vein  at  its  junction 
with  the  jugular.  The  duct  is  so  thin  and  transparent  that  it 
easily  escapes  observation ;  it  is  most  readily  found  by  raising  the 
subclavian  vein  near  its  junction  with  the  jugular,  and  searching 


64  SUBCLAVIAN   ARTERY. 

with  the  handle  of  the  scalpel  on  the  inner  side  of  the  scalenus 
anticus,  in  front  of  the  vertebral  vein. 

Before  tracing  the  branches  of  the  subclavian  artery,  consider 
some  points  relating  to  the  operation  of  tying  it. 

To  tie  the  artery  in  the  first  part  of  its  course,  namely,  on  the 
inner  edge  of  the  scalenus  anticus,  is  an  operation  of  great  difficulty 
and  danger,  even  with  the  parts  in  a  normal  position.  The  great 
depth  at  which  the  artery  is  placed,  the  size  and  close  proximity 
of  its  numerous  branches,  the  large  veins  by  which  it  is  covered, 
its  connection  with  the  pneumogastric,  recurrent  laryngeal,  phrenic, 
and  sympathetic  nerves,  and,  above  all,  its  close  contiguity  with  the 
pleura,  form  a  combination  of  circumstances  so  formidable  that 
one  cannot  be  surprised  the  operation  has  never  been  performed 
with  a  favourable  result. 

In  the  second  part  of  its  course,  between  the  scalene  muscles, 
the  artery  is  more  accessible,  although  it  is  rarely  ligatured  in 
this  situation.  It  would  be  necessary  to  divide  the  clavicular 
origin  of  the  sterno-mastoid,  the  cervical  fascia,  and  the  scalenus 
anticus,  to  reach  the  vessel;  the  phrenic  nerve  and  the  subclavian 
vein  would  be  the  chief  objects  exposed  to  injury.  This  operation 
was  performed  first  and  with  success  by  Dupuytren  in  the  year  1819. 
More  recently  it  has  been  performed  by  Dr.  Warren,  of  Boston. 
The  patient  recovered,  though  the  pleura  was  wounded.* 

But  in  the  last  part  of  its  course,  that  is,  on  the  outer  side  of 
the  scalenus,  the  artery  may  be  tied  with  comparative  facility. 
The  incision  should  be  made  from  three  to  four  inches  in  length, 
parallel  with  the  upper  border  of  the  clavicle.  We  divide  the 
platysma,  some  of  the  supra-clavicular  nerves,  and  the  cervical 
fascia.  The  external  jugular  vein  must  be  drawn  to  the  outer 
side,  or  divided  and  tied  at  both  ends.  With  the  finger  and  the 
handle  of  the  scalpel  we  then  make  our  way  down  to  the  outer 
edge  of  the  scalenus  anticus,  behind  which  the  artery  will  be  found 
lying  upon  the  first  rib.  Kemember  the  tubercle  on  the  inner  edge 
of  the  rib  which  indicates  the  insertion  of  the  scalenus :  this 

*  'Med.  Chirurg.  Trans.,'  vol.  xxix.  p.  25. 


BEANCHES    OP    THE    SUBCLAVIAN   AETEEY.  65 

tubercle  is  the  best  guide  to  the  artery.  It  is  necessary  to  divide 
a  layer  of  fascia  which  immediately  covers  the  vessel  before 
the  needle  can  be  introduced  around  it.  Mr.  Eamsden,  of  St. 
Bartholomew's  Hospital,  was  the  first  who  tied  the  subclavian  in 
the  third  part  of  its  course,  in  the  year  1 809  ;  since  that  time  the 
operation  has  been  repeatedly  performed,  with  very  favourable 
results. 

In  the  hands  of  a  surgeon  possessed  of  a  practical  knowledge 
of  anatomy  the  operation  is  easy,  provided  all  circumstances  be 
favourable ;  but  circumstances  are  often  very  unfavourable.  It 
often  happens  that  the  aneurysmal  or  other  tumour,  on  account  of 
which  the  operation  is  performed,  raises  the  clavicle  beyond  its 
natural  level,  and  so  disturbs  the  parts,  that  to  expose  the  artery 
and  place  a  ligature  around  it  becomes  exceedingly  difficult. 
Under  such  circumstances  one  cannot  be  surprised  that  even 
distinguished  anatomists  have  committed  mistakes.  Sir  Astley 
Cooper  *  failed  in  one  instance.  Dupuytren  perforated  the  artery 
with  the  point  of  the  needle,  and  included  one  of  the  nerves  in  the 
ligature  :  fatal  haemorrhage  was  the  result.f  We  were  present  at 
an  operation  in  which  the  large  nerve  (a  branch  of  the  brachial 
plexus)  which  runs  parallel  with  and  on  a  plane  anterior  to  the 
artery  was  mistaken  for  it  and  tied ;  the  surgeon  being  deceived 
by  the  pulsation  communicated  to  the  nerve. 

BRANCHES  OF  ^e  Branches  of  the  subclavian  extend  so  widely, 

THE  SUBCLAVIAN  that  in  the  present  dissection  we  can  trace  them  only 
ARTERY.  for  a  short  distance.  They  are  four  in  number : 

1 .  The  vertebral. 

2.  The  thyroid  axis,  a  short  thick  trunk  which  gives  off  the 
inferior  thyroid,  supra-scapular,  and  posterior  scapular. 

3.  The  internal  mammary. 

4.  The  superior  intercostal,  which  gives  off  the  deep  cervical. 
As  a  rule,  the  vertebral,  the  thyroid  axis,  and  the  internal 

mammary  are  given  off  -from  the  subclavian  in  the  first  part  of 

*  '  London  Medical  Review,'  vol.  ii.  p.  300. 
j-  'Edinburgh  Med.  and  Surg.  Journal,'  vol.  xvi.  1820. 
F 


66          BRANCHES  OP  THE  SUBCLAVIAN  ARTERY. 

its  course,  and  the  superior  intercostal  in  the  second  part. 
The  most  frequent  deviation  is,  that  the  posterior  scapular  (trans- 
versalis  colli)  arises  from  the  subclavian  in  the  third  part  of  its 
course.* 

VEBTKBEAL  This,  the  first  and  largest  branch,  arises  from 

AHTEEY.  the  upper  part  of  the  subclavian.      For  a  short 

distance  it  lies  in  the  interval  between  the  scalenus  anticus  and 
the  longus  colli.  Here  it  enters  the  foramen  in  the  transverse 
process  of  the  sixth  cervical  vertebra,  and  ascends  through  the 
foramina  in  the  transverse  processes  of  the  succeeding  vertebrae. 
In  the  interval  between  the  axis  and  the  atlas,  the  artery  makes  a 
sigmoid  curve,  that  it  may  not  be  stretched  in  the  rotation  of  the 
head.  Having  traversed  the  foramen  of  the  atlas,  the  artery  curves 
backwards  along  the  groove  in  its  arch,  perforates  the  posterior 
occipito-atlantoid  ligament  and  the  dura  mater,  then  enters  the 
skull  through  the  foramen  magnum,  and  unites  with  its  fellow 
near  the  lower  border  of  the  '  pons  Varolii '  to  form  the  basilar 
artery. 

Directly  after  the  artery  is  given  off  from  the  subclavian,  it  lies 
behind  the  internal  jugular  vein,  and,  on  the  left  side,  behind  the 
thoracic  duct.  As  it  lies  upon  the  groove  on  the  neural  arch  of 
the  atlas  it  is  separated  from  it  by  the  suboccipital  nerve,  and  is 
situated  within  the  suboccipital  triangle. 

The  vertebral  artery  is  accompanied  by  slender  nerves  from 
the  inferior  cervical  ganglion  of  the  sympathetic.  These  nerves 
communicate  with  the  spinal  nerves  forming  the  brachial 
plexus. 

Destined  for  the  brain,  the  vertebral  gives  off  no  branches  in 
the  neck,  except  a  few  small  ones  to  the  deeply-seated  muscles ;  it 
furnishes,  however,  lateral  spinal  branches  to  the  spinal  cord  and 
its  membranes  which  pass  through  the  intervertebral  foramina. 

*  With  reference  to  the  origin  of  the  posterior  scapular  (transversalis  colli)  artery, 
we  made  special  observations  during  the  winter  session  of  1858-59.  We  found  that 
this  artery  was  given  off  most  frequently,  not  by  the  thyroid  axis,  but  by  the  sub- 
clavian in  the  third  part  of  its  course.  Under  these  circumstances  the  superficialis 
colli  a.  generally  came  from  the  thyroid  axis. 


BRANCHES  OP  THE  SUBCLAVIAN  ARTERY.          67 

The  cranial  branches  of  the  vertebral  artery  are  mentioned  at 
length  in  the  description  of  the  arteries  of  the  brain. 

The  vertebral  vein  is  formed  by  small  branches  from  the  muscles 
near  the  foramen  magnum.  It  descends  in  front  of  the  artery 
through  the  foramina  in  the  transverse  processes,  and  emerging 
through  the  transverse  process  of  the  sixth,  joins  the  brachic- 
cephalic  vein.  It  receives  the  veins  from  the  cervical  portion 
of  the  spinal  cord.  In  some  subjects  it  communicates  with 
the  lateral  sinus  by  a  branch  through  the  posterior  condyloid 
foramen. 

The  cervical  nerves  pass  through  the  intervertebral  foramina 
behind  the  vertebral  artery,  so  that  the  artery  runs  behind  its  vein, 
and  in  front  of  the  nerves. 

The  thyroid  axis  arises   from   the   subclavian 
THYHOID  Axis. 

near  the  inner  edge  of  the  scalenus  anticus,  and 
after  a  course  of  a  quarter  of  an  inch  divides  into  three  branches, 
which  take  different  directions ;  namely,  the  inferior  thyroid,  the 
supra-scapular,  and  the  posterior  scapular. 

1.  The  inferior  thyroid  artery  ascends  tortuously  behind  the  sheath 
of  the  common  carotid  and  the  sympathetic  nerve,  to  the  deep  surface  of 
the  thyroid  body,  in  which  it  communicates  freely  with  the  superior 
thyroid  and  with  its  fellow.     Besides  small  branches  to  the  trachea,  the 
oesophagus,  and  the  larynx,  it  gives  off — 

(a)  the  ascending  cervical  artery  which  runs  up  close  to  the  spine, 
between  the  scalenus  anticus  and  the  rectus  capitis  anticus  major,  and 
terminates  in  small  branches,  some  of  which  supply  these  muscles ;  others 
enter  the  intervertebral  foramina,  and  supply  the  spinal  cord  and  its 
membranes. 

2.  The  supra-scapular  artery  (transversalis  humeri)  runs  outwards  over 
the  scalenus  anticus,  then  directly  beneath  and  parallel  with  the  clavicle  : 
crossing  over  the  third  part  of  the  subclavian  artery,  it  passes  beneath 
the  posterior  belly  of  the  omo-hyoid  to  the  superior  border  of  the  scapula. 
Here  it  is  covered  by  the  trapezius,  goes  above  the  transverse  ligament 
which   bridges    over   the    notch,   and    divides   into    branches,    some  of 
which  ramify  above,  others  below,  the  spine  of  this  bone.     It  inosculates 
freely  in  the  infra-spinous  fossa  with  the  dorsalis  scapulae,  a  branch  of  the 

F    2 


68          BRANCHES  OP  THE  SUBCLAVIAN  ARTERY. 

subscapular,  and  with  the  posterior  scapular  artery.  Near  the  notch,  it 
is  joined  by  the  supra-scapular  nerve,  which  runs  through  it.  The 
branches  of  this  artery  are  numerous  but  small,  and  are  as  follow  :  the 
inferior  sterno-mastoid  (p.  25) ;  the  supra-acromial,  which  anastomoses 
with  the  acromio-thoracic  artery;  articular  branches  to  the  shoulder 
joint ;  the  infra-spinous,  which  ramifies  in  the  infra-spinous  fossa ;  and 
the  subscapular,  which  ramifies  in  the  substance  of  the  subscapularis 
muscle. 

3.  The  posterior  scapular  (transversalis  colli)  artery,  of  which  the 
normal  origin  is  said  to  be  from  the  thyroid  axis,  very  frequently  arises 
from  the  subclavian  in  the  last  part  of  its  course.  It  is  larger  than  the 
preceding  artery,  and  runs  tortuously  across  the  side  of  the  neck  (higher 
than  the  supra-scapular),  over  the  scalene  muscles  and  the  great  nerves  of 
the  brachial  plexus  (sometimes  between  them),  and  disappears  beneath 
the  trapezius  and  the  levator  anguli  scapulae  to  reach  the  superior  angle 
of  the  scapula.  It  then  runs  beneath  the  rhomboid  muscles,  which  it 
supplies,  down  to  the  inferior  angle  of  the  scapula,  anastomosing  freely 
with  the  terminations  of  the  supra-  and  sub-scapular  arteries.  In  the 
space  between  the  sterno-mastoid  and  trapezius,  the  posterior  scapular 
gives  off  the  superficialis  colli.  This  vessel  proceeds  tortuously  across 
the  posterior  triangle  of  the  neck  to  the  under  surface  of  the  trapezius, 
to  which,  with  the  levator  anguli  scapulae,  it  is  principally  distributed. 

The  superficialis  colli  often  comes  direct  from  the  thyroid  axis. 

The  veins  corresponding  to  the  supra -scapular  and  posterior 
scapular  arteries  terminate  in  the  external  jugular,  sometimes  in 
the  subclavian.  The  inferior  thyroid  vein  crosses  in  front  of  the 
common  carotid  artery,  and  joins  the  internal  jugular. 

INTERNAL  This  artery  arises  from  the  subclavian  opposite 

MAMMARY.  to  the  thyroid  axis.  It  enters  the  chest  behind 

tbe  subclavian  vein,  and  descends  behind  the  cartilages  of  the  ribs, 
about  half  an  inch  from  the  sternum.  Its  further  progress  will  be 
examined  in  the  dissection  of  the  chest  (p.  121).  The  corresponding 
vein  most  frequently  terminates  in  the  brachio-cephalic. 

SUPERIOR  This  artery  is  given  off  by  the  subclavian  behind 

INTERCOSTAL.  the  scalenus  anticus  on  the  right  side,  and  to  its 

inner  side  on  the  left,  so  that  you  must  divide  the  muscle  to  see  it. 
It  enters  the  chest  behind  the  pleura,  to  the  outer  side  of  the  first 


BRANCHES  OF  THE  SUBCLAVIAN  ARTERY. 


69 


dorsal  ganglion  of  the  sympathetic.  It  runs  over  the  necks  of  the 
first  and  second  ribs,  and  furnishes  the  arteries  of  the  two  upper 
intercostal  spaces,  and  a  posterior  branch  which  is  distributed  to 
the  muscles  of  the  back  and  the  spinal  cord.  It  usually  inoscu- 
lates with  the  first  inter-  FJG.  12. 
costal  branch  of  the  aorta. 
The  corresponding  vein 
terminates  on  the  right 
side  in  the  vena  azygos ; 
on  the  left  in  the  brachio- 
cephalic. 

DEEP  CERVICAL      This  artery 
ARTERY.  arises    from 

the  superior  intercostal, 
seldom  direct  from  the 
subclavian.  It  goes  to  the 
back  of  the  neck  between 
the  first  rib  and  the  trans- 
verse process  of  the  last 
cervical  vertebra,  and 
ascends  between  the  corn- 
plexus  and  the  semi-spinalis 
colli,  both  of  which  it  sup- 
plies. It  sometimes  inos- 
culates with  the  princeps 
cervicis,  a  branch  of  the 
occipital  (p.  55). 

To  test  your  knowledge 
of  the  branches  of  the  sub- 
clavian artery,  reflect  upon 
the  answer  to  the  follow- 
ing question  :  If  the  ar- 
tery were  tied  in  the  first  part  of  its  course  before  it  gives  off  any 
branches,  how  would  the  arm  be  supplied  with  blood  :  The 
answer  is,  by  six  collateral  channels,  as  follow :  1 .  By  the  com- 
munications between  the  superior  and  inferior  thyroid  :  2.  Between 


DIAGRAM    TO    SHOW   THE    INOSCULATIONS    OF    THE 
SUBCLAYIAN    ARTERY. 


70  BEACHIAL    PLEXUS   OF   NERVES. 

the  two  vertebral :  3.  Between  the  internal  mammary  and  the 
intercostals  and  the  epigastric  :  4.  Between  the  thoracic  branches 
of  the  axillary,  and  the  intercostal  branches  of  the  aorta  : 

5.  Between  the  superior  intercostal   and  the   aortic   intercostals. 

6.  Between  the  princeps  cervicis  and  the  deep  cervical.      Most 
of  these  inosculations  are  shown  in  the  diagram,  p.  69. 

Again,  if  the  subclavian  were  tied  in  the  third  part  of  its 
course,  the  circulation  would  be  carried  on  by  the  communications  : 
1.  Between  the  supra-scapular  and  the  dorsalis  scapulae,  a  branch 
of  the  subscapular :  2.  Between  the  supra-acromial  branch  of  the 
supra-scapular  and  the  acromio-thoracic  :  3.  Between  the  posterior 
scapular  and  the  subscapular  and  dorsalis  scapulae  :  4.  Between  the 
internal  mammary,  the  aortic  intercostals  and  superior  intercostal 
on  the  one  hand,  and  the  long  and  short  thoracic  branches  of  the 
axillary,  on  the  other. 

SUBCLAVIAN  The  subclavian  vein  does  not  form  an  arch  like 

VEJN.  the  artery,  but  proceeds  in  a  nearly  straight  line 

over  the  first  rib  to  join  the  internal  jugular.  Throughout  its 
whole  course  the  vein  is  situated  on  a  plane  anterior  to  and  a 
little  lower  than  the  artery,  from  which  it  is  separated  by  the 
scalenus  anticus,  the  phrenic  and  pneumogastric  nerves.  It  has 
a  pair  of  valves  just  before  its  junction  with  the  internal  jugu- 
lar. It  receives  the  anterior  jugular,  the  vertebral,  the  external 
jugular,  and  through  it,  the  supra-scapular  and  posterior  scapular 
veins. 

BRACHIAL  The  large  nerves  forming  the  plexus  which  sup- 

PLEXUS  OF  plies  the  upper  extremity  are  the  anterior  divisions 

NERVES.  of  £he  four  lower  cervical  and  the  first  dorsal,  with 

a  small  fasciculus  derived  from  the  fourth  cervical  nerve.  Emer- 
ging from  the  intervertebral  foramina  they  appear  between  the 
anterior  and  middle  scalene  muscles,  and  pass  with  the  subclavian 
artery  into  the  axilla.  To  this  bundle  of  nerves  the  name  plexus 
is  given,  on  account  of  their  mutual  communications.  The  plexus 
at  its  root  is  wide,  and  situated  higher  than  the  subclavian 
artery,  and  nearly  on  the  same  plane  ;  but  as  the  plexus  descends 
beneath  the  clavicle,  its  component  nerves  converge,  and,  in  the 


BEACHIAL    PLEXUS    OF   NEEVES. 


71 


axilla,  completely  surround  the  artery:  one  cord  lying  to  the 
outer  side,  a  second  lying  to  the  inner  side,  and  a  third  behind 
the  vessel. 

The  plexus  is  crossed  superficially  by  the  omo-hyoid  muscle, 
and  by  the  supra-scapular  and  posterior  scapular  arteries. 

The  arrangement  of  the  nerves  in  the  formation  of  the  plexus 

FIG.  13. 


DIAGRAM    OF   THE   FORMATION    OF   THE    BRACHIAL   PLEXUS    AND    ITS    BRANCHES. 


c  4-8.  Anterior  trunks  of  the  cervical  nerves. 
D  1.  Anterior  trunk  of  the  first  dorsal  n. 
9.  N.  to  the  rhomboid  m. 

10.  Supra  scapular. 

11.  N.  to  snbclavius  m. 
12-13.  Anterior  thoracic. 

14,15,16.  Subscapular  n. 

17.  Lesser  int.  cutaneous. 


18.  Musculo-cutaneous . 

19.  Circumflex. 

20.  Median. 

21.  Musculo-spiral. 

22.  TJlnar. 

23.  Int.  cutaneous. 

24.  Ext.  respiratory  of  Bell. 


is  very  variable,  and  often  not  alike  on  both  sides.  The  most 
usual  arrangement  is,  that  at  the  outer  border  of  the  scalenus 
anticus,  the  fifth  and  sixth  cervical  n.  unite  to  form  an  upper 
trunk ;  the  eighth  and  the  first  dorsal  n.  form  a  lower  trunk ;  the 


72          BKANCHES  OP  THE  BRACHIAL  PLEXUS. 

seventh  cervical  runs  for  some  distance  alone,  and  forms  a  middle 
trunk.  Now  each  of  these  five  primary  nerves  divides  into  an 
anterior  and  a  posterior  branch :  the  anterior  branches  given  off 
from  the  fifth,  sixth,  and  seventh  form  the  outer  cord  of  the  plexus  ; 
the  anterior  branches  given  off  from  the  eighth  cervical  and  first 
dorsal  form  the  inner  cord:  while  the  posterior  branches  of  all 
the  nerves  (namely,  the  fifth,  sixth,  seventh,  eighth  cervical  and 
first  dorsal)  unite  to  form  the  posterior  cord.* 

The  branches  arising  from  the  plexus  are  best  arranged  into 
those  given  off  above  the  clavicle,  and  those  given  off  below  it. 
The  following  are  those  given  off  above  the  clavicle. 

a.  The  branch  forming  one  of  the  roots  of  the  phrenic  arises 
from  the  fifth  cervical.     (Not  in  the  diagram.) 

b.  Nerve  to  the  subclavius  m. — This  proceeds  from  the  fifth 
and  sixth  cervical,  and  crosses  the  subclavian  artery  in  the  third 
part  of  its  course.     It  frequently  sends  a  filament,  which  passes  in 
front  of  the  subclavian  vein  to  join  the  phrenic  nerve. 

c.  Nerves  to  the  scaleni  and  the  longus  colli  muscles  are  given 
off  from  the  lower  cervical  nerves  as  they  leave  the  intervertebral 
foramina. 

d.  Nerve  to  the  rhomboid  muscles. — This  arises  from  the  fifth 
cervical  nerve,  passes  through  the  scalenus  medius,  and  accom- 
panies the  posterior  scapular  artery,  beneath  the  levator  anguli 
scapulae,  which,  as  well  as  the  rhomboid  muscles,  it  supplies. 

e.  The  supra-scapular  nerve  arises  from  the  cord  formed  by 
the  fifth  and  sixth  cervical  n.,  runs  to  the  upper  border  of  the 
scapula,  where  it  meets  with  the  corresponding  artery,  and  then 
passing  through  the  notch  in  the  scapula,  terminates  in  the  supra- 
spinatus  and  infra-spinatus  m. 

/.  The  posterior  thoracic  nerve  (called  external  respiratory 
by  Sir  C.  Bell)  to  the  serratus  magnus  arises  from  the  fifth  and 
sixth  cervical,  in  the  substance  of  the  scalenus  medius.  It  passes 
through  this  muscle  and  subsequently  emerges  below  the  rhomboid 

*  For  a  description  of  the  arrangement  of  the  nerves  constituting  the  plexus,  see 
a  paper  by  Lucas,  'Guy's  Hospital  Reports,'  1875;  also  Turner  in  the  'Journal  of 
Anatomy,'  1872. 


DISSECTION    OF    THE    FACE.  73 

nerve-;  it  then  descends  behind  the  plexus  and  the  subclavian 
vessels  to  the  outer  surface  of  the  serratus  magnus,  to  the  several 
digitations  of  which  it  is  exclusively  distributed. 

g.  An  articular  branch  is  distributed  to  the  shoulder  joint; 
besides  some  filaments  to  the  constituent  bones. 

It  only  remains  to  be  observed  that  the  upper  cord  of  the 
brachial  plexus  receives  a  branch  from  the  lower  cord  of  the  cer- 
vical, and  that  each  of  its  component  nerves  communicates  by 
slender  filaments  with  the  sympathetic. 

Below  the  clavicle  the  plexus  divides  into  branches  for  the 
supply  of  the  arm ;  namely,  the  anterior  thoracic  nerves  (two  in 
number,  to  the  pectoralis  major  and  minor),  the  subscapular  (three 
in  number,  to  the  subscapularis,  the  latissimus  dorsi,  and  teres 
major),  the  circumflex  (to  the  deltoid  and  teres  minor),  the 
median,  the  musculo-spiral,  the  ulnar,  the  external  cutaneous, 
the  internal  cutaneous,  and  the  lesser  internal  cutaneous  (nerve  of 
Wrisberg)  :  all  of  which  will  be  described  more  fully  in  the  dissec- 
tion of  the  arm. 

DISSECTION   OF  THE  FACE. 

Much  practice  is  required  to  make  a  good  dissection  of  the  face. 
The  muscles  of  expression  are  numerous  and  complicated  ;  they 
are  interwoven  with  the  subcutaneous  tissue  and  closely  united  to 
the  skin  :  their  fibres  are  often  pale  and  indistinct.  The  face  is 
largely  supplied  with  motor  and  sensory  nerves,  of  which  the 
ramifications  extend  far  and  wide.  Therefore  you  must  not  be 
discouraged  if,  in  a  first  attempt,  you  fail  to  make  a  satisfactory 
display  of  the  parts. 

The  cheeks  and  nostrils  should  be  distended  with  horse-hair, 
and  the  lips  sewn  together. 

Make  an  incision  down  the  mesial  line  of  the  face ;  another 
from  the  chin  along  the  base  of  the  lower  jaw  to  the  angle  ;  then 
prolong  it,  in  front  of  the  ear,  to  the  zygoma.  Eeflect  the  skin 
from  below  upwards.  Each  muscle,  to  be  properly  cleaned,  should 
be  stretched  by  hooks. 


74  MUSCLES    OF    THE    FACE. 

The  student  is  recommended  to  make  out  the  muscles  and 
arteries  on  the  one  side,  leaving  the  other  side  for  the  display  of 
the  nerves. 

The  motor  nerve  which  supplies  all  the  muscles  of  expression  in 
the  face  is  the  'partio  dura,'  or  facial  division  of  the  seventh  cranial 
nerve.  It  emerges  from  the  stylo-mastoid  foramen,  and  divides 
into  branches,  which  pass  through  the  parotid  gland,  forming  a 
plexus  termed  the  lpes  anserinus.' 

The  sensory  nerves  of  the  face  are  chiefly  derived  from  the  three 
divisions  of  the  fifth  cranial  nerve ;  namely,  the  supra-orbital, 
the  infra-orbital,  and  the  mental.  The  only  other  nerves  which 
confer  sensation  upon  the  face  are,  the  auriculo-parotidean  branch 
of  the  cervical  plexus  (p.  20),  which  supplies  the  skin  covering  the 
parotid  gland  and  part  of  the  cheek ;  and  the  naso-lobular.  which 
supplies  the  ala  and  tip  of  the  nose. 

It  is  convenient  to  arrange  the  muscles  of  the  face  under  three 
groups  ;  appertaining,  respectively,  to  the  mouth,  the  nose,  the  eye- 
brows and  lids.  Begin  with  those  of  the  mouth. 

The  muscles  of  the  mouth  are  arranged  thus  :  there  is  an  orbi- 
cular or  sphincter  muscle  surrounding  the  lips ;  from  this,  as  from 
a  common  centre,  muscles  diverge  and  are  fixed  into  the  surround- 
ing bones.  They  are  named  elevators,  depressors,  sphincters,  &c., 
according  to  their  respective  action. 

MUSCULUS  Riso-  This  muscle  arises  from  the  fascia  over  the  mas- 
Kius  (SANTOHINI).  seter  m.,  and  passes  horizontally  forwards  to  be 
inserted  into  the  angle  of  the  mouth,  where  it  intermingles  with 
the  orbicularis  oris  and  other  muscles  in  this  situation.  It  produces 
the  smile,  not  of  good  humour,  but  of  derision.  This  muscle  is 
usually  considered  as  a  part  of  the  platysma  myoides  (p.  17). 

OKBICULABIS  This  muscle,  nearly  an  inch  in  breadth,  sur- 

°KI8-  rounds  the  mouth,  forming  a  kind  of  sphincter. 

Its  size  and  thickness  in  different  individuals  produce  the  variety 
in  the  prominence  of  the  lips.  Observe  that  its  fibres,  except  the 
most  internal,  do  not  surround  the  mouth  in  one  unbroken  series, 
but  that  those  of  the  upper  and  lower  lip  decussate  at  the  angles 
of  the  mouth,  and  intermingle  with  the  fibres  of  the  buccinator  and 


MUSCLES   OP   THE    FACE.  75 

other  muscles  which  converge  from  different  parts  of  the  face.* 
The  cutaneous  surface  of  the  muscle  is  intimately  connected  with 
the  lips  and  the  surrounding  skin  ;  the  deep  surface  is  separated 
from  the  mucous  membrane  by  the  labial  glands  and  the  coronary 
vessels.  . 

The  orbicularis  is  the  antagonist  of  all  the  muscles  which  move 
the  lips.  Upon  a  nice  balance  of  their  opposite  actions  depends 
the  play  and  infinitely  varied  expression  of  the  mouth.f 

DEPRESSOR  This  muscle  arises  broadly  from  the  oblique 

ANGUH  ORIS.  line  of  the  lower  jaw  behind  the  foramen  mentale, 

and  is  inserted  narrowly  into  the  angle  of  the  mouth,  interming- 
ling with  the  zygomatic  muscles.  It  is  an  important  muscle 
in  the  expression  of  sorrowful  emotions.  We  see  its  action  when 
children  cry. 

DE  This  muscle  arises  from  the  oblique  line  of  the 

LABU  INFERIORS,  lower  jaw  below  the  foramen  mentale,  and  is  in- 
OR  QUADRATUS  swted  into  the  lower  lip.  It  covers  the  vessels 

and  nerves  which  emerge  from  the  foramen. 
This  muscle  arises  from  the  lower  jaw,  from  the  fossa  below  the 

LEVATORMENTI  incisor  teeth,  and,  passing  down,  is  inserted  into 
OR  LEVATOR  LABU  the  skin  of  the  chin.  To  see  it,  evert  the  lower 
INFERIORIS.  \{p  anc[  remove  the  mucous  membrane  on  either 

side  of  the  frsenum.  There  are  two  of  them,  one  for  each  side. 
Their  action  is  well  seen  when  we  shave  the  chin,  or  protrude  the 
lower  lip. 

*  The  orbicularis  consists  of  two  parts,  an  inner  or  labial  part,  and  an  outer  or 
facial ;  the  difference  in  appearance  of  the  fibres  being  very  marked.  The  labial  part 
consists  of  pale  thin  fibres,  forming  more  or  less  of  the  inner  part  of  the  orbicularis, 
and  has  no  attachment  to  bone ;  the  facial  part  is  thinner  but  broader,  and  besides 
being  connected  with  other  muscles,  is  attached  to  bone  thus: — in  the  upper  lip  by  two 
fasciculi  on  each  side,  one  to  the  septum  nasi,  the  other  to  the  alveolar  border  oppo- 
site the  incisor  teeth ;  in  the  lower  lip  by  a  single  fasciculus  to  the  lower  jaw  on 
each  side  opposite  the  canine  tooth. 

f  In  strong  muscular  lips  the  upper  part  of  the  orbicularis  sends  a  small  sub- 
cutaneous slip  of  muscle  from  each  side  along  the  septum  nasi  nearly  to  the  apex. 
The  interval  between  the  two  slips  corresponds  to  the  furrow  which  leads  from  the 
nose  to  the  lip.  This  is  the  naso-labialis  or  depressor  septi  narium  of  Haller  and 
Albinus. 


76  MUSCLES    OP   THE    FACE. 

ZTGOMATICUS  The  Z.  major  arises  from  the  outer  surface  of 

MAJOR  AND  the  malar  bone  close  to  its  suture  with  the  zygoma, 

MINOB-  passes  obliquely  downwards  and  inwards,  and  is 

inserted  into  the  angle  of  the  mouth,  joining  the  depressor  anguli 
oris.  The  Z.  minor  arises  from  the  outer  surface  of  the  malar 
bone,  in  front  of  the  preceding,  and  is  inserted  into  the  outer 
border  of  the  levator  labii  superioris  near  the  corner  of  the  mouth. 
The  zygomaticus  minor  is  often  absent.  The  zygomaticus  major 
is  the  muscle  of  laughing  :  the  minor  expresses  sadness. 

Before  examining  the  orbicularis  palpebarum,  notice  the  tendo 
oculi.  To  make  the  tendon  more  apparent,  the  tarsal  cartilages 
should  be  drawn  outwards. 

TENDO  OCULI  This  tendon  is  a  thin  cord  about  two  lines  *  in 

OR  PALPEBRARUM.  length,  and  is  readily  felt  at  the  inner  angle  of  the 
eye  by  drawing  the  eyelids  outwards.  It  is  fixed  to  the  nasal 
process  of  the  superior  maxillary  bone,  in  front  of  the  lachrymal 
groove,  passes  horizontally  outwards,  and  divides  into  two  diver- 
ging portions,  one  of  which  is  attached  to  the  upper,  the  other  to 
the  lower  tarsal  cartilage.  The  tendon  crosses  the  lachrymal  sac 
a  little  above  the  centre,  and  furnishes  a  tendinous  expansion  which 
covers  the  sac  and  is  attached  to  the  margin  of  the  bony  groove 
which  contains  it.  To  see  this  expansion  we  must  reflect  that 
portion  of  the  orbicularis  palpebrarum  which  covers  the  sac. 

In  puncturing  the  lachrymal  sac  the  knife  is  introduced  below 
the  tendon,  in  a  direction  downwards,  outwards,  and  a  little  back- 
wards. We  have  to  divide  the  skin,  a  few  fibres  of  the  orbicularis, 
and  the  fibrous  expansion  from  the  tendo  palpebrarum.  The 
angular  artery  and  vein  are  situated  on  the  inner  side  of  the 
incision. 

ORBICULARIS  This  thin  broad  muscle  surrounds  the  margin 

PALPEBRARUM.  of  the  orbit  and  the  eyelids,  forming  a  sphincter. 
It  is  attached  on  the  inner  side  to  the  tendo  palpebrarum,  to  the 
nasal  process  of  the  superior  maxillary  bone,  to  the  internal  angular 
process  of  the  frontal  bone,  and  to  the  lower  margin  of  the  orbit. 

*  A  line  is  the  twelfth  part  of  an  inch. 


MUSCLES    OP   THE    FACE.  77 

From  this  attachment  the  fibres  form  a  series  of  oval  curves,  taking 
a  wide  sweep,  and  pass  uninterruptedly  round  the  eyelids  and  orbit. 

The  fibres  which  belong  to  the  eyelids  (orbicularis  palpebrarum) 
are  thin  and  pale,  and  form,  over  each  eyelid,  a  series  of  elliptical 
curves  which  meet  at  the  external  canthus  of  the  lids,  and  are 
loosely  attached  to  the  external  tarsal  ligament.  The  degree  of  their 
curvature  .becomes  less  as  they  approach  the  margin  of  the  lids,  so 
that  some  fibres  proceed  close  to  the  lashes.  This  was  first  pointed 
out  by  Eiolanus,*  and  described  as  the  musculus  ciliarisj  The 
fibres  which  spread  over  the  orbital  margins  are  thicker  and  redder, 
and  mingle,  on  the  forehead,  with  the  occipito-frontalis  and  corru 
gator  supercilii,  on  the  cheek,  with  the  elevators  of  the  upper  lip 
and  nose  and  the  zygomaticus  minor. 

No  fat  is  found  on  the  eyelids ;  nothing  intervenes  between 
the  skin  and  the  muscle  but  loose  connective  tissue,  that  there  may 
be  no  impediment  to  the  free  play  of  the  lids. 

The  orbicular  muscle  not  only  closes  the  eyelids  but  protects 
the  eye.  When  the  eye  is  threatened,  the  muscle  suddenly  con- 
tracts, presses  the  eye  back  into  the  orbit,  and  contracts  the  skin 
of  the  brow  and  cheek  so  as  to  form  a  soft  cushion  in  front  of  it. 
The  cushion  itself  may  be  severely  bruised,  as  is  seen  in  a 
'  black  'eye ; '  but  the  globe  itself  is  rarely  injured.  When  the 
eye  is  closed,  as  in  winking,  the  palpebral  portion  of  the  muscle 
contracts.  Observe  this  movement,  and  notice  that  the  lids  are 
drawn  slightly  inwards  as  well  as  closed.  The  object  of  this  in- 
ward motion  is  to  direct  the  tears  towards  the  inner  angle  of  the 
eyelids,  where  they  are  absorbed  by  the  puncta  lachrymalia. 

Since  the  orbicular  muscle  is  supplied  by  the  facial  nerve,  it  is 
affected  in  facial  palsy,  and  the  patient  cannot  close  the  lids. 

CORRUGATOR  This  arises  from  the  inner  end  of  the  super- 

SUPERCIUI.  ciliary  ridge  of  the  frontal  bone,  and  is  inserted 

into  the  under  surface  of  the  orbicularis  palpebrarum  and  occipito- 

*  '  Anthropologia,'  lib.  v.  cap.  1 0. 

f  Strictly  speaking,  the  musculus  ciliaris  arises  from  the  two  little  divisions  of 
the  tendo  oculi,  and  is  inserted,  at  the  external  canthus,  into  the  fibrous  tissue  which 
unites  the  two  tarsal  cartilages. 


78  STRUCTURE    OF    THE    EYELIDS. 

frontalis.  It  lies  concealed  beneath  these  two  muscles,  and  is  the 
proper  muscle  of  frowning.  Its  nerve  comes  from  the  facial. 

The  present  being  a  good  opportunity  to  examine  the  structure 
and  appendages  of  the  eyelids,  postpone  for  the  present  the  dissec- 
tion of  the  remaining  muscles  of  the  face. 

The  eyelids  are  two  elliptical  movable  folds,  consisting  of 
strata  of  different  tissues.  The  upper  lid  is  the  larger,  and  more 
movable,  so  that  when  the  eye  is  closed,  it  is  mainly  by  this  fold. 
The  interval  between  the  two  lids  is  called  the  'fissura  palpe- 
brarumj  which  terminates  on  the  inner  and  outer  sides,  in  two 
angles,  the  canthi.  The  lids  are  thickest  at  their  borders,  are 
somewhat  curved,  and  near  the  inner  canthus  each  presents  a  slight 
elevation,  the  papilla  lachrymalis,  at  the  top  of  which  is  a  small 
opening,  punctum  lachrymale,  to  receive  the  tears. 

CAHUNCULA  The  conjunctiva  lines  the  inner  surface  of  the 

LACHBYMALIS.  lids,  and  at  the  inner  canthus  is  raised  into  a  red 

rounded  eminence,  called  the  caruncula  lachrymalis.  This  is  com- 
posed of  an  aggregation  of  sebaceous  glands  covered  with  mucous 
membrane.  On  the  surface  of  it  are  minute  hairs.  Its  use  is, 
probably,  to  support  the  inner  junction  of  the  lids.  When  the 
caruncle  is  diminished  in  size  by  disease,  the  puncta  lachrymalia 
become  displaced,  and  the  tears  run  down  the  cheek. 

External  to  the  caruncula  lachrymalis  is  a  slight  vertical  fold 
of  conjunctiva,  plica  semilunaris,  which  is  by  some  considered  to 
be  a  rudimentary  membrana  nictitans  (the  third  eyelid  found  in 
birds). 

The  conjunctival  coat  of  the  eyelid  will  be  described  with  the 
anatomy  of  the  eye.  Observe  at  present,  that  it  is  more  vascular 
than  the  conjunctival  coat  of  the  eye,  and  that  it  presents  a  num- 
ber of  minute  papillse,  which,  when  enlarged  and  aggregated  by 
inflammation,  give  rise  to  the  disease  called  '  granular  lids.' 

The  eyelashes  (cilia)  are  placed  in  two  or  more  rows  along  the 
edges  of  the  tarsal  cartilages.  The  eyelashes  of  the  upper  lid  are 
longer  and  more  numerous  than  in  the  lower ;  and  their  convexity 
is  directed  downwards,  while  those  of  the  lower  lid  present  an 
opposite  curve.  The  bulbs  of  the  lashes  are  situated  between  the 


STRUCTURE    OF    THE    EYELIDS.  79 

tarsal  cartilage  and  the  fibres  of  the  orbicularis  palpebrarum. 
They  are  supplied  with  blood  by  the  palpebral  branches  of  the 
ophthalmic  artery  which  run  parallel  and  close  to  the  free  borders 
of  the  lids  beneath  the  orbicular  muscle. 

STRUCTURE  OF  The  eyelids  are  composed  of  different  tissues,  ar- 

THE  EYELIDS.  ranged  in  successive  strata  one  beneath  the  other. 

They  are — 1.  The  skin  :  2.  The  orbicularis  palpebrarum  :  3.  The 
tarsal  cartilage,  and  the  palpebral  ligament  which  extends  from 
the  margin  of  the  orbit  to  the  outer  surface  of  the  cartilage : 
4.  The  expanded  tendon  of  the  levator  palpebrse  (in  the  upper  lid 
only) :  5.  Meibomian  glands :  6.  Mucous  membrane.  These 
structures  are  severally  connected  by  areolar  tissue,  which  never 
contains  fat. 

Such,  in  outline,  is  the  structure  of  the  eyelids.  Their  use  is 
best  described  by  Socrates,  who,  in  answer  to  the  question  whether 
animals  were  made  by  chance  or  design,  replies :  '  Think  you 
not  that  it  looks  like  the  work  of  forethought,  because  the  sight  is 
delicate,  to  guard  it  with  eyelids  as  with  shutters,  which  open 
when  we  want  to  see.  and  shut  during  sleep ;  and,  that  even  winds 
may  not  hurt  them,  to  make  eyelashes  in  the  lids  for  a  sieve ; 
and  to  furnish  the  parts  over  the  eyes  with  eyebrows,  as  with 
eaves,  so  that  even  the  sweat  from  off  the  head  may  do  them  no 
mischief? '  * 

The  skin  of  the  eyelids  is  remarkably  smooth  and  delicate.  It 
is  abundantly  supplied  with  sensory  nerves  by  branches  of  the 
fifth  pair — namely,  by  the  supra-orbital,  supra-trochlear,  infra- 
trochlear,  lachrymal,  and  infra-orbital  nerves. 

The  orbicularis  palpebrarum  has  been  already  described 
(p.  76).  It  is  supplied  with  nerves  by  the  facial. 

The  levator  palpebrce  arises  from  the  back  of  the  orbit,  gradually 
becomes  broader,  and  terminates  in  a  thin  aponeurosis,  which 

*  Xenophon's  Memorabilia,  b.  1.  c.  iv.  §  6  :  ov  SoKe?  ao\.  Kal  r6$e  trpovoias  fpyovtoucf- 
vai,  76,  4vf\  affBev^is  fnev  IGTIV  j]  otyts,  f)\e<f>dpoi$  avTrjv  OvpHtrai,  fi,  8-rav  fj.(v  avrfj  %pricr€ai 
n  5«7,  £a>a.ircT<ii>i>vra.i,  4v  Se  Ttf  virvtf  <rvyK\eifTai ;  &s  8'  av  jurjSe  favepoi  $X6.irT<a<riv,  rj 
/3\e<fiapt5as  t/j.Qvffai  •  6<f>pvfft  re  airoytiffuffat  ra  inrtp  rwv  o^ndraiv,  is  MlS'  ^  fit 
Kf(pa\ris  IS 


80  STKUCTURE   OP   THE    EYELIDS. 

unites  with  the  broad  tarsal  ligament,  and  is  lost  on  the  upper 
surface  of  the  superior  tarsal  cartilage. 

TAKSAL  CAETI-  These  are  plates  of  dense  fibre-cartilage  which 
LAGES  AND  LioA-  support  and  give  shape  to  the  eyelids.  There  is 
MENTS-  one  for  each  lid,  and  they  are  connected  at  the 

angles  (commissures  or  canthi)  of  the  lids  through  the  me- 
dium of  fibrous  tissue.  They  can  be  best  examined  by  everting 
the  lids.  Each  cartilage  resembles  its  lid  in  form.  The  upper 
is  the  larger,  is  broad  in  the  middle,  and  gradually  becomes 
narrower  at  either  end.  The  lower  is  nearly  of  uniform  breadth 
throughout.  Both  are  thicker  on  the  nasal  than  the  temporal 
side.  They  are  connected  to  the  margin  of  the  orbit,  and  main- 
tained in  position  by  the  tendo  palpebrarum  (p.  76),  and  by  what  are 
called  the  broad  tarsal  or  palpebral  Ligaments :  these  ligaments 
are  continuations  from  the  periosteum  of  the  orbit  to  the  tarsal 
cartilages,  and  are  denser  at  the  outer  part  of  the  orbit.  There 
are  two  of  them,  termed  upper  and  lower,  and  proceeding  to  each 
cartilage  respectively.  When  an  abscess  forms  in  the  connective 
tissue  of  the  lids,  these  ligaments  prevent  the  matter  from  making 
its  way  into  the  orbit. 

Each  tarsal  cartilage  is  moreover  attached  to  the  malar  bone  by 
means  of  a  ligament,  called  the  external  tarsal  ligament. 

The  ciliary  margin  is  the  thickest  part  of  the  tarsal  cartilages. 
It  is  generally  stated  that  the  inner  edge  of  each  is  sloped  or 
bevelled  off ;  and  that,  when  the  lids  are  closed,  there  is  formed, 
with  the  globe  of  the  eye,  a  triangular  channel.  This  channel  is 
said  to  conduct  the  tears  to  the  puncta  lachrymalia.  According  to 
our  observation,  this  channel  does  not  exist ;  for  when  the  lids  are 
closed,  their  margins  are  in  such  accurate  apposition,  that  not  the 
slightest  interspace  can  be  discovered  between  them. 

PUNCTA  The  puncta  lachrymalia  are  two  pin-hole  aper- 

LACHBTMALIA.  tures,  easily  discovered  on  the  margin  of  the  lids, 
close  to  the  inner  angle.  They  are  the  orifices  of  the  canals,  called 
canaliculi,  which  pass  inwards,  and  convey  the  tears  into  the 
lachrymal  sac.  Observe  that  their  orifices  are  directed  backwards. 
The  upper  canaliculus,  the  longer  and  narrower  of  the  two,  ascends 


STRUCTURE    OP   THE    EYELIDS.  81 

for  a  short  distance  nearly  vertically,  and  then  dilating  into  a  small 
pouch  makes  a  sharp  bend  inwards  for  about  a  quarter  of  an  inch 
to  join  the  lachrymal  sac ;  the  lower  canal  descends  perpendicularly, 
and,  like  the  upper,  makes  a  sharp  bend,  after  which  it  pursues  a 
direction  upwards  and  inwards  to  the  sac.  The  two  canals  open 
separately  into  the  sac  (sometimes  by  FlG  14 

a  commoD  orifice).  In  facial  palsy,  the 
tensor  tarsi  being  affected,  the  puncta 
lose  their  proper  direction,  and  the 
tears  flow  over  the  cheek. 

In  the  introduction  of  probes 
for  the  purpose  of  opening  the  con- 
tracted puncta,  or  of  slitting  up  the 
lachrymal  ducts,  it  is  necessary  to 
know  the  exact  direction  of  these 
canals.  (See  diagram.)  When  from 
any  cause  the  tears  are  secreted  in 
greater  quantity  than  usual,  they  overflow  and  trickle  down  the  cheek 
MEIBOMIAN  These  compound  sebaceous  glands,  so  called 

GLANDS.  after  the  anatomist*  who  first  described  them, 

are  situated  on  the  under  surface  of  each  of  the  tarsal  carti- 
lages. In  the  upper  lid  there  are  between  twenty  and  thirty ; 
not  quite  so  many  in  the  lower.  On  everting  the  lid,  they  are 
seen  running  in  longitudinal  rows  in  grooves  of  the  cartilage. 
Under  the  microscope,  they  are  seen  to  consist  of  a  straight  central 
tube,  round  the  sides  of  which  are  a  number  of  openings  leading 
to  short  caecal  dilatations.  The  orifices  of  these  glands  are  situated 
on  the  free  margin  of  the  lids  behind  the  lashes.  They  are  lined 
with  flattened  epithelial  cells  which,  in  the  csecal  dilatations, 
become  cubical.  Their  function  is  to  secrete  a  sebaceous  material, 
which  prevents  the  lids  from  sticking  together. 

Let  us  now  examine  the  muscles  in  connection  with  the  nose  : 
namely — the  pyramidalis  nasi,  the  compressor  naris  or  alse  nasi, 
and  the  depressor  al»  nasi.  All  are  supplied  by  the  facial  nerve. 

*  H.  Meibom,  'De  yasis  palpebrarum  novis.'    Helmstedt,  1666. 
G 


82  MUSCLES   OF   THE    FACE. 

PTRAMIDAMS  This  is  situated  on  the  bridge  of  the  nose,  one 

NASI-  on  each  side  of  the  mesial  line,  and  is  usually 

regarded  as  a  continuation  of  the  occipito-frontalis  (p.  2).  The  two 
muscles  diverge  as  they  descend,  and  their  fibres  blend  with  those 
of  the  compressor  naris.  Their  action  produces  transverse  wrinkles 
of  the  skin  at  the  root  of  the  nose,  as  in  the  expression  of  an 
aggressive  feeling. 

COMPBESSOR  This   muscle  is  triangular,  and  arises  by  its 

NAHIS.  apex  from  the  canine  fossa  of  the  superior  max- 

illa, and  is  attached  to  a  broad  thin  aponeurosis  which  spreads 
over  the  dorsum  of  the  nose,  and  joins  its  fellow.  The  origin  of 
this  muscle  is  concealed  by  the  levator  labii  superioris  alseque 
nasi. 

When  the  preceding  muscle  is  reflected  from  its  junction  with 
its  fellow,  a  small  nerve  is  seen  running  down  towards  the  tip  of 
the  nose.  This  nerve  is  the  superficial  branch  of  the  nasal  nerve 
(called  also  naso-lobular).  It  becomes  subcutaneous  between 
the  nasal  bone  and  the  cartilage,  and  supplies  the  tip  and  lobule 
of  the  nose.  It  is  joined  by  a  branch  of  the  facial  nerve  at  its 
termination. 

DEPRESSOR  AIM         This  arises  from  the  superior  maxilla,  above 
NASI-  the  second  incisor  tooth,  and  is  inserted  into  the 

septum  and  ala  of  the  nose.  It  is  situated  between  the  mucous 
membrane  and  the  muscular  structure  of  the  upper  lip ;  so  that, 
to  expose  it,  the  upper  lip  must  be  everted,  and  the  mucous  mem- 
brane removed. 

Besides  the  muscles  above  described,  we  find  in  connection 
with  the  cartilages  of  the  alee  of  the  nose,  pale  muscular  fibres  which 
have  no  very  definite  arrangement  and  require  a  lens  for  their 
detection.  Some  anatomists  describe  a  ' dilatator  naris  posterior' 
as  arising  from  the  nasal  process  of  the  superior  maxilla  and  the 
sesamoid  cartilages,  and  inserted  into  the  skin  of  the  margin  of 
the  nostril ;  also  a  dilatator  naris  anterior,  which  descends  verti- 
cally from  the  cartilage  of  the  aperture  to  its  free  margin.  The 
action  of  these  diminutive  muscles  is  to  raise  and  evert  the  ala  of 
the  nose,  and  to  counteract  its  tendency  to  be  closed  by  atmo- 


MUSCLES    OF    THE    FACE.  83 

spheric  pressure.  In  dyspnoea,  and  in  certain  mental  emotions, 
they  contract  with  great  energy. 

LETATOH  LABU          This  arises  from  the  nasal  process  of  the  su- 
SUPERIORIS  perior  maxillary  bone  near  its  orbital  margin,  and 

AL^EQUE  NASI.  passing  downwards  divides  into  two  portions  :  au 
inner,  inserted  into  the  side  of  the  ala  of  the  nose ;  an  outer,  into 
the  upper  lip,  where  its  fibres  blend  with  the  orbicularis  oris  and 
levator  labii  superioris.  It  acts  chiefly  in  expressing  the  smile  of 
derision.  Its  habitual  use  occasions  the  deep  furrow  which,  in  most 
faces,  runs  from  the  ala  of  the  nose  towards  the  corner  of  the  mouth. 

LEVATOR  LABU          This  arises  from  the  lower  margin  of  the  orbit, 
SUPERIORIS  i.e.  from  the  superior    maxilla   and   malar   bone, 

above  the  infra-orbital  foramen,  and  is  inserted 
into  the  upper  lip,  where  its  fibres  blend  with  the  orbicularis  oris. 
It  is  nearly  an  inch  in  breadth  at  its  origin,  which  covers  the 
infra-orbital  vessels  and  nerves,  and  is  itself  overlapped  by  the 
orbicularis  palpebrarum. 

LEVATOR  This  muscle,  which  is  covered  by  the  levator 

ANGULI  ORIS.  labii  superioris,  arises  from  the  canine  fossa  of  the 

superior  maxilla,  below  the  infra-orbital  foramen,  and  is  inserted 
into  the  angle  of  the  mouth,  superficial  to  the  buccinator,  its  fibres 
blending  with  those  of  the  the  orbicularis  oris,  the  zygomatici,  and 
the  depressor  anguli  oris. 

The  buccinator  arises  from  the  outer  surface  of 
the  alveolar  borders  of  the  upper  and  lower  jaws, 
corresponding  to  the  molar  teeth,  and  from  the  ptery go-maxillary 
ligament.  The  fibres  pass  forwards  and  are  inserted  into  the  angle 
of  the  mouth  and  the  muscular  structure  of  the  lips ;  the  central 
fibres  decussate,  while  the  upper  fibres  pass  to  the  upper  lip,  and 
the  lower  fibres  pass  to  the  lower  lip.  The  muscle  is  covered  on 
its  inner  aspect  by  the  mucous  membrane  of  the  cheek,  and  on  its 
outer  by  a  thin  fascia  which  passes  backwards,  and  is  continuous 
with  that  covering  the  pharynx. 

The  buccinator  is  the  principal  muscle  of  the  cheek.  It  forms 
with  the  superior  constrictor  of  the  pharynx  a  continuous  muscular 
wall  for  the  side  of  the  mouth  and  pharynx.  The  bond  of  connec- 

G    2 


84 


MUSCLES    OF   THE    FACE. 


tion  between  the  buccinator  and  the  superior  constrictor  is  the 
ptery go-maxillary  ligament.  Now  this  ligament  (see  diagram) 
extends  from  the  Iwnular  process  vertically  to  the  posterior 
extremity  of  the  mylo-hyoid  ridge  of  the  lower  jaw  near  the  last 

FIG.  15. 


Tensor  palati. 
Levator  palati. 


Orbieularis  oris    . 

Pterygo-maxillary 

ligament  .    .    - 


Mylo-hyoideue . 

Os-hyoides  .    .    . 
Thyro-hyoid   liga- 
ment   .    .    .    . 


Pomum  Adami 


Cricoid  cartilage 
Trachea  .    ..    . 


Gloeso-pharyngeal  n. 
Stylo-pharyngeus. 


Superior  laryngeal 
n.  and  a. 


External  laryngeal  n. 
Crico-thyroideus. 

Inferior  laryngeal  n. 
(Esophagus. 


MUSCLES    OF    THE    PHARYNX. 


molar  tooth.     It  is  simply  a  fibrous  intersection  between  the  two 
muscles. 

The  duct  of  the  parotid  gland  passes  obliquely  through  the 
buccinator  into  the  mouth,  opposite  the  second  molar  tooth  of  the 
upper  jaw. 


ARTEEIE8    OF   THE    FACE.  85 

The  chief  use  of  the  buccinator  is  to  keep  the  food  between  the 
teeth  during  mastication.  It  can  also  widen  the  mouth.  Its 
power  of  expelling  air  from  the  mouth,  as  in  whistling  or  playing 
on  a  wind  instrument,  has  given  rise  to  its  peculiar  name.  It  is 
supplied  by  the  facial  nerve,  and  is,  therefore,  affected  in  facial 
paralysis. 

The  buccinator  muscle  is  covered  by   a   thin 
BUCCAL  FASCIA.  . 

layer  of  fascia,  which  adheres  closely  to  its  surface, 

and  is  attached  to  the  alveolar  border  of  the  upper  and  lower 
jaw.  This  structure  is  thin  over  the  anterior  part  of  the  muscle, 
but  more  dense  behind,  where  it  is  continuous  with  the  aponeurosis 
of  the  pharynx.  It  is  called  the  bucco-pharyngeal  fascia,  since 
it  supports  and  strengthens  the  muscular  walls  of  these  cavities. 
In  consequence  of  the  density  of  this  fascia,  abscesses  do  not  readily 
burst  into  the  mouth  or  the  pharynx. 

BUCCAL  AND  The  buccal  glands,  in  structure  compound  race- 

MOLAR  GLANDS.  mose  like  the  salivary,  are  situated  between  the 
buccinator  and  the  mucous  membrane.  They  resemble  the  labial 
glands  found  beneath  the  mucous  membrane  of  the  lips,  though 
somewhat  smaller.  Three  or  four  other  glands,  about  the  size 
of  a  little  split  pea,  should  be  made  out,  as  they  lie  between  the 
masseter  and  buccinator;  these  are  the  molar  glands.  Their 
secretion,  said  to  be  mucous,  is  conveyed  to  the  mouth  by  separate 
ducts  near  the  last  molar  teeth. 

Between  the  buccinator  and  the  masseter,  there  is,  in  almost  all 
subjects,  an  accumulation  of  fat.  It  is  found,  beneath  the  zygoma 
especially,  in  large  round  masses,  and  may  be  turned  out  with  the 
handle  of  the  scalpel.  It  helps  to  fill  up  the  zygomatic  fossa, 
and  being  soft  and  elastic,  presents  no  obstacle  to  the  free 
movements  of  the  jaw.  Its  absorption  in  emaciated  individuals 
occasions  the  sinking  of  the  cheek. 

The  facial  (external  maxillary)   artery  is  the 

third   branch   of  the  external  carotid.      It   runs 

tortuously  beneath  the  hypoglossal  nerve,  the  posterior  belly  of  the 

digastricus  and  the  stylo-hyoideus,  next  through  or  under  the 

substance  of  the  submaxillary  gland,  and  mounts  over  the  base  of 


86  ARTERIES    OF   THE    FACE. 

the  jaw  at  the  anterior  edge  of  the  masseter  muscle.  Up  to  this 
point  we  traced  it  in  the  dissection  of  the  neck  (page  45).  It  now 
ascends  tortuously  near  the  corner  of  the  mouth  and  the  ala  of  the 
nose,  towards  the  inner  angle  of  the  eye,  where,  much  diminished 
in  size,  it  inosculates  with  the  terminal  branch  of  the  ophthalmic,  a 
branch  of  the  internal  carotid.  In  the  first  part  of  its  course  on  the 
face,  the  artery  is  covered  only  by  the  platysma  ;  above  the  corner 
of  the  mouth  it  is  crossed  by  a  few  fibres  of  the  orbicularis  oris 
and  the  zygomatici ;  still  higher  it  is  covered  by  some  of  the  fibres 
of  the  elevators  of  the  upper  lip  and  the  nose.  It  lies  successively 
upon  the  buccinator,  levator  anguli  oris,  and  levator  labii  superioris 
muscles.  In  its  course  along  the  face  it  gives  off  the  following 
branches  : 

a.  The  inferior  labial  artery  passes  inwards   under   the   depressor 
anguli  oris  and  inosculates  with  the  mental  branch  of  the  inferior  dental, 
tlie  inferior  coronary,  and  the  submental  arteries. 

b.  The  inferior  coronary  artery  comes  off  near  the  angle  of  the  mouth, 
either  directly  from  the  facial,  or  in  common  with  the  superior  coronary. 
It  runs  tortuously  along  the  lower  lip,  beneath  the  depressor  anguli  oris ; 
it  then  pierces  the  orbicularis,  running  between  this  muscle  and  the 
mucous  membrane  of  the  lip.     It  inosculates  largely  with  its  fellow,  the 
inferior  labial  and  the  mental  arteries. 

c.  The  superior  coronary  proceeds  along  the  upper  lip  close  to  the 
mucous  membrane,  and  inosculates  with   its  fellow ;    thus   is    formed 
round  the  mouth  a  complete  arterial  circle,  which  can  be  felt  pulsa- 
ting on  the  inner  side  of  the  lip,  near  the  free  border.      From  this 
circle  numerous  branches  pass  off  to  the  papillae  of  the  lips,  and  the 
labial  glands.     The  superior  coronary  gives  off  a  branch,  the  artery  of 
the  septum,  which  ascends  along  the  septum  to  the  apex  of  the  nose ; 
also  a  small  one  to  the  ala  nasi. 

d.  The  lateral  artery  of  the  nose,  a  branch  of  considerable  size,  arises 
opposite  the  ala  nasi  beneath  the  levator  labii  superioris  alseque  nasi, 
ramifies  upon  the  external  surface  of  the  nose,  and  inosculates  with  the 
nasal  branch  of  the  ophthalmic  artery,  the  infra-orbital,  and  the  artery  of 
the  septum. 

e.  The  angular  artery,  which  may  be  regarded  as  the  termination  of 
the  facial,  inosculates  on  the  inner  side  of  the  tendo  palpebrarum  with 
the  nasal  branch  of  the  ophthalmic  artery. 


ARTERIES    OF    THE    PACE.  87 

The  facial  artery  supplies  numerous  branches  to  the  muscles  of 
the  face,  and  inosculates  with  the  transversalis  faciei,  infra-orbital, 
the  mental,  the  sublingual  branch  of  the  lingual,  the  nasal 
branches  of  the  internal  maxillary,  the  buccal,  and  the  ophthalmic 
arteries. 

The  facial  artery  and  its  branches  are  surrounded  by  a  minute 
plexus  of  nerves  (nervi  molles),  invisible  to  the  naked  eye.  They 
are  derived  from  the  superior  cervical  ganglion  of  the  sympa- 
thetic, and  exert  a  powerful  influence  over  the  contraction  and 
dilatation  of  the  capillary  vessels,  and  thus  occasion  those  sudden 
changes  in  the  countenance  indicative  of  certain  mental  emotions, 
e.g.  blushing  or  sudden  paleness.* 

The  facial  vein  does  not  run  with  the  artery,  but  takes  a 
straight  course  from  the  inner  angle  of  the  eye  to  the  anterior 
border  of  the  masseter.  In  this  course  it  descends  upon  the 
levator  labii  superioris,  then  passes  beneath  the  zygomatic  muscles, 
over  the  termination  of  the  parotid  duct,  and  at  the  anterior 
border  of  the  masseter  passes  over  the  jaw,  behind  the  facial 
artery,  and  joins  the  internal  jugular. 

The  facial  vein  is  a  continuation  of  the'  frontal,  which  descends 
over  the  forehead,  and,  after  receiving  the  supra-orbital,  takes  the 
name  of  '  angular '  at  the  corner  of  the  eye.  It  communicates  with 
the  ophthalmic  vein,  receives  the  veins  of  the  eyelids,  the  external 
parts  of  the  nose,  the  coronary  veins,  and  others  from  the  muscles 
of  the  face.  Near  the  angle  of  the  mouth  it  is  increased  in  size 
by  a  communicating  branch  from  the  infra-orbital  vein,  and  by  a 
large  vein  which  conies  from  a  venous  plexus — pterygoid  plexus 
— deeply  seated  behind  the  superior  maxillary  bone.  The  other 
veins  which  empty  themselves  into  the  facial  correspond  with  the 
branches  given  off  from  the  facial  artery. 

AKTEEIA  This   artery  arises  from  the   temporal  or  the 

TRANSVERSALIS          external  carotid  in  the  substance  of  the  parotid 
FACIEI.  gland.      It   runs   forwards    across    the    masseter 

*  MM.  Bernard  and  Brown-S^quard  have  proved  by  experiment  that  if  the  branches 
of  the  sympathetic,  which  accompany  the  facial  artery,  be  divided,  the  capillary  vessels 
of  the  face,  being  deprived  of  their  contractile  power,  become  immediately  distended 
with  blood,  and  the  temperature  of  the  face  is  raised. 


88  PAROTID    GLAND. 

between  the  parotid  duct  and  the  zygoma,  and  is  distributed  to 
the  glandula  socia  parotidis,  and  the  masseter.  It  anastomoses 
with  the  infra-orbital  and  facial.  It  is  seldom  of  large  size,  except 
when  it  supplies  those  parts  which  usually  receive  blood  from  the 
facial.  We  have  seen  it  as  large  as  a  goose-quill,  furnishing  the 
coronary  and  the  nasal  arteries ;  the  facial  itself  not  being  larger 
than  a  sewing  thread. 

The  parotid  gland  is  now  to  be  examined.  Its  boundaries,  its 
deep  relations,  the  course  of  its  duct,  and  the  objects  contained 
within  the  gland,  must  be  carefully  observed. 

PABOTID  The  parotid,  the  largest  of  the  salivary  glands, 

GLAND-  occupies  the  space  between  the  ramus  of  the  jaw 

and  the  mastoid  process.  It  is  bounded  above  by  the  zygoma ; 
below,  by  the  sterno-mastoid  and  digastric  muscles ;  behind,  by  the 
meatus  auditorius  externus  and  the  mastoid  process ;  in  front,  it 
lies  over  the  ascending  ramus  of  the  jaw,  and  is  prolonged  for  some 
distance  over  the  masseter.  It  is  separated  from  the  subinaxillary 
gland  by  the  stylo-maxillary  ligament ;  sometimes  the  two  glands 
are  directly  continuous. 

The  superficial  surface  of  the  gland  is  flat,  and  covered  by  a 
strong  layer  of  fascia,  a  continuation  of  the  cervical.  It  not  only 
surrounds  the  gland,  but  sends  down  numerous  partitions  which 
form  a  framework  for  its  lobes.  The  density  of  this  sheath  explains 
the  pain  caused  by  inflammation  of  the  gland,  the  tardiness  with 
which  abscesses  within  it  make  their  way  to  the  surface,  and  the 
propriety  of  an  early  opening. 

The  deep  surface  of  the  gland  is  irregular,  and  moulded  upon 
the  subjacent  parts.  Thus,  it  passes  inwards  between  the  neck  of 
the  jaw  and  the  internal  lateral  ligament;  it  extends  upwards  and 
occupies  the  posterior  part  of  the  glenoid  cavity ;  below,  it  reaches 
the  styloid  process,  and  sometimes  penetrates  deep  enough  to  be 
in  contact  with  the  internal  jugular  vein. 

That  portion  of  the  gland  which  lies  on  the  masseter  muscle  is 
called  glandula  socia  parotidis.  It  varies  in  size  in  different 
subjects ;  and  is  situated  chiefly  above  the  parotid  duct,  into  which 
it  pours  its  secretion  by  one  or  two  smaller  ducts. 


PAEOTID    GLAND.  89 

The  duct  of  the  parotid  gland  (ductus  Stenonis*),  about 
two  inches  long,  is  very  thick  and  strong.  In  this  respect  it 
differs  from  the  duct  of  the  submaxillary  gland,  which  is  less 
exposed  to  injury.  It  runs  transversely  forwards  over  the  mas- 
seter,  about  an  inch  below  the  zygoma,  through  the  fat  of  the 
cheek,  then  perforates  the  buccinator  obliquely,  and  opens  into 
the  mouth  opposite  the  second  molar  tooth  of  the  upper  jaw. 
Near  its  termination  it  is  crossed  by  the  zygomaticus  major  and 
the  facial  vein.  After  perforating  the  buccinator,  the  duct  passes 
for  a  short  distance  between  the  muscle  and  the  mucous  membrane. 
Its  orifice  is  small  and  contracted  compared  with  the  diameter 
of  the  rest  of  the  duct,  which  will  admit  a  crow-quill ;  it  is  not 
easily  found  in  the  mouth,  being  concealed  by  a  fold  of  mucous 
membrane. 

The  direction  of  the  parotid  duct  corresponds  with  a  line  drawn 
from  the  middle  of  the  lobule  of  the  ear  to  a  point  midway  between 
the  nose  and  the  mouth. 

On  carefully  removing  the  substance  of  the  parotid  gland,  the 
following  structures  are  seen  in  its  interior,  proceeding  in  the  order 
of  their  depth  from  the  surface  : 

1.  Two  or  more  small  lymphatic  glands. 

2.  The    pes    anserinus,    or   primary    branches    of    the   facial 
nerve. 

3.  Branches  from  the  auriculo-parotidean  and   temporo-auri- 
cular  nerves  which  communicate  in  its  substance  with  the  facial 
nerve. 

4.  The  external  jugular  vein  formed  by  the  junction  of  the 
internal  maxillary  and  temporal  veins. 

5.  The  external  carotid  artery,  which,  after  distributing  many 
branches  to  the  gland,  divides,  opposite  the  neck  of  the  jaw,  into 
the  internal  maxillary  and  temporal ;  the  latter  giving  off  in  the 
gland  the  auricular  and  transverse  facial  arteries.f 

*  Nic.  Steno,  'De  glandulis  oris,'  etc.     Ludg.  Bat.  1661. 

j-  Reviewing  the  intimate  and  deep  connections  of  the  parotid  gland,  one  cannot 
but  conclude  that  it  is  almost  impracticable  to  remove  it  entirely  during  life.  If  this 
conclusion  be  correct,  even  in  the  normal  condition  of  the  gland,  what  must  it  be  when 


90  NEBVES   OF   THE    PACE. 

The  lymphatic  glands  about  the  parotid  deserve  notice,  since 
they  are  liable  to  become  enlarged,  and  simulate  disease  of  the 
parotid  itself.  A  lymphatic  gland  lies  close  to  the  root  of  the 
zygoma,  in  front  of  the  cartilage  of  the  ear ;  this  gland  is  some- 
times affected  in  disease  of  the  external  tunics  of  the  eye ;  e.g. 
in  purulent  ophthalmia  :  also  in  affections  of  the  scalp. 

The  parotid  belongs  to  the  compound  racemose  form  of  glands. 
Tracing  its  main  duct  into  the  substance  of  the  gland,  we  find  that  it 
divides  into  smaller  ones,  which  again  subdivide  into  the  small  ra- 
muscules  which  terminate  in  caecal  dilatations  or  saccules.  Each,  saccule 
— about  -j-^Viy  °f  an  inch  ^n  diameter — is  filled  with  flattened,  spheroidal 
epithelium,  inclosing  a  nucleus,  some  of  them  having  an  outstanding 
process  from  the  base  of  the  cell.  The  saccule  bas  a  more  or  less  de- 
veloped basement  membrane  upon  which  tbe  flattened  cells  rest.  An 
aggregation  of  these  saccules  forms  a  small  lobule,  from  which  a  small 
excretory  duct  proceeds ;  the  lobules  are  united  by  intervening  connective 
tissue,  wbicb  is  a  continuation  inwards  of  tbe  dense  fascia  covering  the 
gland.  Tbe  small  ramuscules  bave  only  a  basement  membrane  witb 
flattened  cells,  which  rapidly  change  in  the  smaller  ducts  to  a  columnar 
form,  while  in  tbe  larger  ducts  tbe  epithelium  assumes  tbe  squamous 
variety. 

To  display  the  plexus  of  nerves  (pes  anserinus),  formed  by  the 
branches  of  the  facial  in  the  parotid  gland,  find  one  of  the  larger 
branches,  say  one  of  the  malar,  on  the  face,  and  trace  this  into  the 
substance  of  the  gland,  as  a  clue  to  the  others. 

PORTIO  DURA,  This  is  one  of  the  divisions  of  the  seventh  pair 

OR  FACIAL  NERVE,  of  cranial  nerves,  and  is  the  motor  nerve  of  the 
face.  It  supplies  all  the  muscles  of  expression,  except  those  which 
move  the  eyes.  It  arises  immediately  below  the  pons  Varolii, 
from  the  lateral  tract  of  the  medulla  oblongata.  The  nerve  enters 
the  meatus  auditorius  internus,  lying  upon  the  auditory  nerve, 
traverses  a  tortuous  bony  canal  (aqueductus  Fallopii}  in  the 

the  gland  is  enlarged  by  disease  ?  John  Bell,  however,  relates  a  case  in  which  he  was 
induced  to  attempt  the  extirpation  of  a  diseased  parotid  ('Principles  of  Surgery,' 
vol.  iii.  p.  262).  Other  surgeons,  too,  of  more  modern  date,  have  attempted  the  same 
thing.  It  is  not  unlikely  that  they  have  mistaken  a  tumour  in  the  substance  of  the 
parotid  for  disease  of  the  parotid  itself. 


NERVES    OP   THE    FACE.  91 

petrous  portion  of  the  temporal  bone,  and  leaves  the  skull  at  the 
stylo-mastoid  foramen.  Its  course  and  connections  in  the  temporal 
bone  will  be  studied  hereafter  :  at  present  we  must  trace  the  facial 
part  of  the  nerve. 

Having  emerged  from  the  stylo-mastoid  foramen,  the  nerve 
enters  the  parotid  gland,  and  soon  divides  into  two  primary 
branches,  named,  from  their  distribution,  temporo-facial  and 
cervico-facial.  These  primary  branches  cross  over  the  external 
carotid  artery  and  the  external  jugular  vein,  and  form,  by  their 
communications  within  the  substance  of  the  parotid,  the  plexus 
called  pes  anserinus,  from  its  fancied  resemblance  to  the  skeleton 
of  a  goose's  foot.  (Diagram,  p.  4.) 

Close  to  the  stylo-mastoid  foramen,  the  facial  nerve  gives  off 
its  posterior  auricular  branch  (p.  4),  which  ascends  behind  the 
ear  and  divides  into  two,  an  auricular  and  an  occipital ;  the  former 
supplies  the  retrahens  and  attollens  aurem,  the  latter  the  posterior 
belly  of  the  occipito-frontalis.  This  branch  communicates  with  the 
great  auricular  n.  and  with  the  auricular  branch  of  the  pneumo- 
gastric.  Its  two  next  branches  supply  the  posterior  belly  of  the 
digastricus  and  the  stylo-hyoideus.  The  digastric  nerve  enters  the 
muscles  by  many  filaments ;  the  nerve  to  the  stylo-hyoid  is  long 
and  enters  the  muscle  about  the  middle.  The  digastric  branch 
communicates  with  the  glosso-pharyngeal  near  the  base  of  the 
skull :  the  stylo-hyoid  branch  with  the  sympathetic  on  the  external 
carotid  a.  These  two  muscular  nerves  are  frequently  given  off 
from  a  common  branch. 

The  temporo-facial  division,  the  larger  of  the  two,  crosses 
the  external  carotid  and  the  neck  of  the  jaw,  receives  two  or 
more  communications  from  the  auriculo-temporal  (branch  of  the 
fifth)  and  subdivides  into  temporal,  malar,  and  infra-orbital 
branches. 

The  temporal  branches  ascend  over  the  zygoma,  supply  the  frontalis, 
the  attrahens  aurem,  the  orbicularis  palpebrarum,  the  corrugator  super- 
cilii,  and  tensor  tarsi,  and  communicate  with  filaments  of  the  supra-orbital 
nerve,  with  the  temporal  branch  of  the  superior  maxillary  n.,  and  with 
the  auriculo-temporal  n. 


92  NERVES    OP   THE    FACE. 

The  malar  branches  cross  the  malar  bone,  supply  the  orbicular 
muscle,  and  communicate  with  filaments  of  the  lachrymal,  the  supra- 
orbital,  the  superior  maxillary,  and  the  malar  branch  of  the  superior 
maxillary. 

The  infra- orbital  branches  are  the  largest,  and  proceed  transversely 
forwards  beneath  the  zygomatici  over  the  masseter,  to  supply  the  orbicu- 
laris  oris,  the  elevators  of  the  upper  lip,  and  the  muscles  of  the  nose.  Be- 
neath the  levator  labii  superioris  there  is  a  free  communication  with  the 
infra-orbital  branches  of  the  superior  maxillary  nerve,  forming  the  infra- 
orbital  plexus.  Along  the  side  of  the  nose  the  terminal  filaments  join 
the  nasal  and  infra-trochlear  branches  of  the  ophthalmic. 

The  cervico-facial  division,  joined  in  the  parotid  gland  by 
filaments  from  the  auriculo-parotidean  (branch  of  the  cervical 
plexus),  descends  towards  the  angle  of  the  jaw,  and  subdivides 
into  buccal,  supra-  and  infra-maxillary  branches. 

The  buccal  branches  pass  forwards  over  the  masseter  parallel  with 
the  parotid  duct,  and  supply  the  buccinator  :  they  communicate  with  the 
buccal  branch  of  the  inferior  maxillary  nerve  (third  division  of  the 
fifth). 

The  supra-maxillary  branches  advance  over  the  masseter  and  facial 
artery,  and  run  under  the  depressor  muscles  of  the  lower  lip,  all  of  which 
they  supply.  Some  of  the  filaments  communicate  with  the  mental  branch 
of  the  inferior  dental  nerve. 

The  infra-maxillary  or  cervical  branches,  one  or  more  in  number, 
were  dissected  with  the  neck  (p.  21).  They  arch  forwards  below  the  jaw 
covered  by  the  platysma,  as  low  as  the  hyoid  bone,  and  communicate 
with  the  superficial  cervical  (branch  of  the  cervical  plexus). 

Respecting  the  function  of  the  facial  nerve,  it  is,  at  its 
origin,  purely  a  motor  nerve ;  but  after  leaving  the  stylo-mastoid 
foramen  it  becomes  a  compound  nerve,  in  consequence  of  the 
filaments  which  it  receives  from  the  auriculo-temporal  branch 
of  the  fifth,  and  from  the  auriculo-parotidean  branch  of  the 
cervical  plexus.  These  communications  explain  the  pain  which 
is  often  felt  in  facial  paralysis  along  the  track  of  the  facial 
nerves. 


NERVES   OF   THE    FACE.  93 

SENSOBT  These  are  the  supra-orbital,  the  supra-  and  infra- 

NEBVES  OF  THE        trochlear,    the   naso-lobula,r,   the   temporo-malar, 
FACE>  the  infra-orbital,  and  the  mental,  all  branches  of 

the  fifth  pair. 

The  supra-orbited  nerve  is  a  branch  of  the  first  division  of 
the  fifth  pair.  It  leaves  the  orbit  through  the  supra-orbital 
notch,  and  is  at  first  covered  by  the  orbicularis  and  occipito- 
frontalis.  But  it  presently  divides  into  wide-spreading  branches, 
which  supply  the  skin  of  the  forehead,  upper  eyelid,  and  scalp.  It 
communicates  with  the  facial  nerve  on  the  forehead.  The  supra- 
orbital  artery  is  a  branch  of  the  ophthalmic. 

The  supra-trochlear  n.,  or  internal  frontal,  appears  at  the 
inner  angle  of  the  orbit,  and  sends  down,  in  front  of  the  pulley  of 
the  obliquus  superior  oculi,  a  loop  to  communicate  with  the  infra- 
trochlear.  Its  further  course  has  been  described  (p.  4). 

The  infra-trochlear  n.  issues  from  the  orbit  below  the  pulley, 
and  supplies  branches  to  the  eyelids,  the  mucous  membrane, 
lachrymal  sac,  and  the  side  of  the  nose. 

The  infra-orbital  nerve  is  the  terminal  branch  of  the  superior 
maxillary  or  second  division  of  the  fifth  nerve.  It  emerges  with 
its  artery  from  the  infra-orbital  foramen,  covered  by  the  levator 
labii  superioris.  The  nerve  immediately  divides  into  several 
branches,  palpebral,  nasal,  and  labial ;  the  palpebral,  ascending 
beneath  the  orbicularis,  supply  the  lower  eyelid,  and  communicate 
with  the  facial:  the  nasal  pass  inwards  to  supply  the  nose  and  join 
the  nasal  branch  (naso-lobular)  of  the  first  division  of  the  fifth ; 
the  labial,  by  far  the  most  numerous,  descend  into  the  upper  lip, 
and  eventually  terminate  in  lashes  of  filaments,  which  endow  the 
papillae  of  the  lip  with  exquisite  sensibility.  Close  to  the  infra- 
orbital  foramen  is  the  infra-orbital  plexus,  before  alluded  to  (p.  92). 
The  infra-orbital  artery  is  the  terminal  branch  of  the  internal 
maxillary ;  it  supplies  the  muscles,  the  skin,  and  the  front  teeth 
of  the  upper  jaw,  and  inosculates  with  the  transverse  facial,  buccal, 
facial,  and  coronary  arteries. 

The  naso-lobular  nerve  is  distributed  to  the  tip  and  lobule  of 
the  nose,  and  is  joined  by  filaments  from  the  facial  nerve. 


94  TEMPORAL   REGION. 

The  temporo-mala/r  nerve,  one  or  more  (branch  of  the  supe- 
rior maxillary),  issues  through  the  canal  in  the  malar  bone  and 
supplies  the  cheek  and  side  of  the  temple. 

The  mental  nerve  is  a  branch  of  the  inferior  maxillary  or  third 
division  of  the  fifth.  It  emerges  from  the  mental  foramen  in  the 
lower  jaw,  in  a  direction  upwards  and  backwards,  beneath  the 
depressor  labii  inferioris.  It  soon  divides  into  a  number  of 
branches,  some  of  which  supply  the  skin  of  the  chin,  but  the 
greater  number  terminate  in  the  papillae  of  the  lower  lip.  It 
communicates  with  the  facial  nerve. 

The  mental  artery  is  a  branch  of  the  inferior  dental.  It  sup- 
plies the  gums  and  the  chin,  and  inosculates  with  the  sub-mental, 
the  inferior  labial,  and  inferior  coronary  arteries. 


MUSCLES  OF  MASTICATION.— TEMPORAL  AND  PTERYGO-MAXILLARY 

REGIONS. 

In  this  dissection,  the  parts  should  be  examined  in  the  following 
order : 

1.  Superficial  arteries  and  nerves  of  the      5.  Pterygoid  muscles. 

temple.  6.  Internal    maxillary    artery  and 

2.  Masseter  muscle.  branches. 

3.  Temporal  aponeurosis.  7.  Inferior    maxillary    nerve    and 

4.  Temporal  muscle.  branches. 

Eeflect  the  skin  of  the  temple  from  below  upwards.  Beneath 
the  skin  you  come  upon  a  layer  of  tough  connective  tissue,  con- 
tinuous, above,  with  the  aponeurosis  of  the  scalp,  below,  with  the 
fascia  covering  the  masseter  and  the  parotid  gland.  In  this  tissue 
are  contained  the  superficial  temporal  vessels  and  nerves. 

TEMPORAL  This  is  the  smaller  of  the  two  terminal  branches 

ARTERY.  of  the   external    carotid.      Arising   in  the    sub- 

stance of  the  parotid  gland  near  the  neck  of  the  jaw,  it  passes 
over  the  root  of  the  zygoma,  close  to  the  meatus  auditorius, 
ascends  for  about  1^  inches  on  the  temporal  fascia,  and  there 
divides  into  an  anterior  and  a  posterior  branch.  Above  the 
zygoma  it  is  superficial,  being  covered  only  by  the  attrahens 


TEMPORAL   REGION.  95 

aurem ;  here  it  is  accompanied  by  the  auriculo-temporal  branch 
of  the  inferior  division  of  the  fifth  nerve.  It  gives  off  the  follow- 
ing branches : 

a.  Several  small  branches  to  the  parotid  gland,  the  temporo-maxillary 
articulation,  and  the  masseter. 

b.  The  transversalis  faciei  (p.  87). 

c.  The  anterior  auricular  branches,  two  in  number,  superior  and 
inferior,  ramify  on  the  front  of  the  pinna  of  the  ear,  inosculating  with 
the  posterior  auricular. 

d.  The  middle  temporal,  a  small  vessel,  pierces  the  temporal  fascia 
above  the  zygoma,  and  running  in  the  substance  of  the  temporal  muscle, 
anastomoses  with  the  temporal  branches  of  the  internal  maxillary. 

Of  the  two  branches  into  which  the  temporal  divides,  the  anterior 
runs  tortuously  towards  the  external  angle  of  the  frontal  bone,  distant 
from  it  about  an  inch.  Its  ramifications  extend  over  the  forehead, 
supplying  the  orbicularis  and  frontalis  m.,  and  inosculate  with  the  supra- 
orbital  and  frontal  arteries.  The  posterior  runs  towards  the  back  of  the 
head,  and  inosculates  freely  with  the  occipital  and  posterior  auricular. 
The  anterior  branch,  although  the  smaller,  is  usually  selected  for 
arteriotorny,  the  posterior  being  covered  by  a  strong  and  unyielding 
fascia. 

ATJHIOTLO-TEM-  This  nerve  supplies  the  temple  and  side  of  the 
POBAT,  NBEVB.  head  with  common  sensation.  It  arises  from  the 
third  division  of  the  fifth  pair  by  two  roots  (between  which  the 
middle  meningeal  artery  runs).  From  its  origin  it  proceeds  out- 
wards beneath  the  external  pterygoid,  between  the  neck  of  the  jaw 
and  the  internal  lateral  ligament.  It  then  ascends  beneath  the 
parotid,  over  the  root  of  the  zygoma,  where  it  accompanies  the 
temporal  artery,  and  divides,  like  it,  into  an  anterior  and  a  posterior 
branch.  Its  ramifications  correspond  with  those  of  the  artery. 

Near  the  condyle  of  the  jaw  the  auriculo-temporal  nerve  sends 
round  the  external  carotid  artery  communicating  branches  to  the 
upper  division  of  the  facial  nerve,  endowing  it  with  common  sen- 
sibility. It  here  distributes  branches  to  the  parotid  gland,  the 
meatus  auditorius,  the  membrana  tympani,  and  the  articulation  of 
the  jaw.  Above  the  zygoma  it  gives  off  two  filaments  (auricular], 
an  upper  and  a  lower  ;  the  upper  ramifies  in  the  skin  of  the  outer; 


96  TEMPOEAL   REGION. 

aspect  of  the  ear,  mainly  on  the  tragus  and  upper  half  of  the  auricle ; 
the  lower  supplies  the  lobule  and  lower  part  of  the  pinna. 

Lastly,  in  the  subcutaneous  tissue  of  the  temple,  we  find  the 
temporal  branches  of  the  facial  nerve,  which  supply  the  frontalis, 
the  attrahens  aurem,  the  orbicularis  palpebrarum,  tensor  tarsi,  and 
corrugator  supercilii. 

MASSETEE  This  muscle  arises  from  the  lower  edge  of  the 

MUSCLE.  zygoma,  and  is  inserted  into  the  outer  side  of  the 

ramus  and  coronoid  process  of  the  jaw.  The  masse ter  is  com- 
posed of  superficial  and  deep  fibres  which  cross  like  the  letter  X. 
The  superficial  fibres,  constituting  the  principal  part  of  the  muscle, 
arise  from  the  anterior  two-thirds  of  the  zygoma  by  tendinous 
fibres  which  occupy  the  front  border  of  the  muscle,  and  send 
aponeurotic  partitions  into  its  substance.  These  fibres  pass  down- 
wards and  backwards,  this  direction  giving  them  greater  advantage, 
and  are  inserted  into  the  angle  and  part  of  the  ramus  of  the  jaw. 
The  deep  fibres,  mainly  muscular  (which  are  concealed  by  the 
parotid  gland),  arise  from  the  posterior  third  of  the  zygoma,  incline 
forwards,  and  are  inserted  into  the  upper  half  of  the  ramus  a,nd 
the  coronoid  process.  Besides  these,  a  few  fibres,  arising  from  the 
inner  surface  of  the  zygoma,  are  inserted  into  the  coronoid  pro- 
cess and  the  tendon  of  the  temporal  muscle.  Its  action  is  to 
raise  the  jaw  and  help  to  masticate  the  food. 

The  following  objects  lie  upon  the  masseter :  1.  Glandula 
socia  parotidis,  and  parotid  duct :  2.  Transversalis  faciei  artery : 
3.  Facial  artery  and  vein :  4.  Branches  of  the  facial  nerve. 

Reflect  the  masseter  from  its  origin  and  turn  it 

DISSECTION 

downwards.  Observe  the  direction  of  the  super- 
ficial and  deep  fibres,  and  the  tendinous  partitions  which  augment 
the  power  of  the  muscle  by  increasing  its  extent  of  origin.  The 
masseteric  nerve  and  artery  enter  the  under  surface  of  the  muscle 
near  to  its  posterior  border,  through  the  sigmoid  notch  of  the 
jaw  ;  the  artery  comes  from  the  internal  maxillary,  the  nerve  from 
the  motor  division  of  the  inferior  maxillary. 

TEMPORAL  This  strong  shining  membrane  covers  the  tem- 

APONEUEOSIS.         poral  muscle ;  its  chief  use  being  to  give  additional 


PTERYGO-M AXILLARY    KEGION.  97 

origin  to  its  fibres.  It  is  attached  above  to  the  temporal  ridge, 
and  increasing  in  thickness  as  it  descends,  divides  near  the  zygoma 
into  two  layers,  which  are  attached  to  the  outer  and  inner  surfaces 
of  the  zygomatic  arch.  These  layers  are  separated  by  fat,  in 
which  is  found  a  filament  from  the  orbital  branch  of  the  superior 
maxillary  nerve.  The  density  of  this  aponeurosis  explains  why 
abscesses  in  the  temporal  fossa  rarely  point  outwards ;  the  pus 
generally  makes  its  way,  beneath  the  zygoma,  into  the  mouth. 

Eeflect  the  aponeurosis,  and  notice  that  it  is  separated  from 
the  temporal  muscle,  near  the  zygoma,  by  fat.  The  absorption  of 
this  fat,  and  the  wasting  of  the  muscle,  occasion  the  sinking  of  the 
temple  in  emaciation  and  old  age. 

TEMPORAL  This  muscle  arises  from  the  whole  of  the  tem- 

MUSCLE.  poral  fossa  (except  the  malar  surface)  and  the  tem- 

poral aponeurosis.  Its  fibres  converge  to  a  strong  tendon  which  is 
inserted  into  the  inner  surface,  the  apex,  and  anterior  border  of 
the  coronoid  process. 

The  fibres  of  the  muscle  converging  from  their  wide  origin, 
pass  under  the  zygomatic  arch,  and  terminate  upon  their  tendon, 
the  outer  surface  of  which  is  partially  concealed  by  the  insertion 
of  those  fibres  which  come  from  the  temporal  aponeurosis  :  remove 
them,  and  see  how  admirably  this  tendon  radiates  into  the  muscle 
like  the  ribs  of  a  fan.  Its  nerves  (two  deep  temporal)  are  branches 
of  the  inferior  maxillary  (p.  104). 

Between  the  posterior  border  of  this  muscle  and  the  neck  of 
the  inferior  maxilla,  the  masseteric  nerve  and  artery  pass  to  their 
destination  :  in  front  of  the  muscle,  the  buccal  branch  of  the  inferior 
maxillary  nerve  descends  to  the  buccinator  with  its  companion 
artery. 

PTEHTGO-MAX-  Divide  the  zygomatic  arch  on  each  side  of  the 
ILLAKT  REGION.  masseter,  and  turn  it  down,  to  expose  the  coronoid 
process  of  the  jaw,  the  insertion  of  the  temporal  muscle,  and  the 
loose  fat  which  surrounds  it.  Next,  saw  through  the  coronoid 
process  in  a  direction  downwards  and  forwards,  so  as  to  include 
the  insertion  of  the  muscle,  and  reflect  it  upwards  without  injuring 
the  subjacent  vessels  and  nerves. 

H 


98 


PTERYGO-MAXILLARY    REGION. 


DISSECTION. 


To  gain  a  good  view  of  the  muscles,  nerves,  and 
vessels  of  the  pterygo-maxillary  region,  a  portion  of 
the  ascending  ramus  of  the  jaw  must  be  removed  with  a  Key's 
saw,  as  shown  in  the  diagram  below. 

In  this  region  we  have  to  examine  the  two  pterygoid  muscles, 
the  trunk  and  branches  of  the  internal  maxillary  artery,  the  inferior 
maxillary  nerve,  and  the  internal  lateral  ligament  of  the  lower  jaw. 
All  these  structures  are  imbedded  in  loose  soft  fat,  which  must  be 
cautiously  removed  without  injuring  them. 


Anterior  deep  temporal  n.  and  a. 


FIG.  16. 

External  pterygoid  m. 

Posterior  deep  temporal  n.  and  a. 
Masse teric  n.  and  a. 


Infra-orbital  a .    , 

Spheno-maxillary 

fossa     .    .    .     . 

Superior  dental  a  . 
Buccal  a  .    .    .    . 

Parotid  duct     .    . 

Buccal  n  .    .    .    , 

Pterygo-maxillary 

ligament  .    .    . 


Inter-articular 
fibro-cartilage. 

Temporal  artery 
and  auriculo- 
temporal  nerve. 


Middle  meningeal  a. 

Inferior  dental  a. 
Inferior  dental  n. 
Gustatory  n. 
Mylo-hyoid  n. 
Internal  pterygoid  m. 


PTSRYGOID    MUSCLES    AND    INTERNAL    MAXILLARY    ARTERY. 


EXTERNAL 
PTERYGOID. 


This  muscle  arises  by  two  heads,  one,  the  upper, 
from  the  great  wing  of  the  sphenoid  and  from  the 
ridge  below  it ;  the  lower,  from  the  outer  surface  of  the  external 
pterygoid  plate,  a  few  fibres  taking  origin  from  the  outer  side 


PTEEYGO-MAXILLAEY   EEGION.  99 

of  the  tuberosities  of  the  palate  and  superior  maxillary  bones.  It 
is  inserted  into  the  neck  of  the  jaw,  and  slightly  into  the  border 
of  the  inter-articular  nbro-cartilage  of  the  jaw. 

The  advantage  of  the  insertion  of  some  of  its  fibres  into  the 
inter-articular  cartilage  is,  that  the  cartilage  follows  the  condyle 
in  all  its  movements.  When  the  jaw  is  dislocated,  it  is  chiefly  by 
the  action  of  this  muscle,  which  draws  the  condyle  forwards  into 
the  zygomatic  fossa ;  the  inter-articular  cartilage  being  dislocated 
with  the  condyle. 

INTERNAL  This  muscle  arises  from  the  inner  surface  of  the 

PTEBTOOID.  .  external  pterygoid  plate  of  the  sphenoid  bone,  and 

the  tuberosity  of  the  palate  bone.  It  is  inserted  into  the  inner 
side  of  the  angle  of  the  jaw,  as  high  as  the  dental  foramen. 

Notice  particularly  the  direction  of  the  fibres  of  the  pterygoid 
muscles.  The  fibres  of  the  external  run  horizontally  outwards 
and  backwards  from  their  origin ;  the  fibres  of  the  internal  run 
downwards,  backwards  and  outwards  from  their  origin.  The 
internal  pterygoid  has  tendinous  septa  like  the  masseter.  Both 
the  pterygoids  get  their  nerves  from  the  motor  division  of  the 
inferior  maxillary. 

The  pterygoid  muscles  produce  the  lateral  movements  of  the 
jaw  essential  to  the  mastication  of  the  food.  Consequently  they 
are  enormously  developed  in  all  ruminants,  and  comparatively 
feebly  in  carnivorous  animals. 

Saw  through  the  neck  of  the  jaw,  disarticulate 
the  condyle  with  its  fibro-cartilage  from  the 
glenoid  cavity,  and  turn  it  forwards  with  the  external  pterygoid, 
so  that  the  condyle  can  be  replaced  if  desirable.  A  little  dissec- 
tion will  bring  into  view  the  internal  lateral  ligament,  and  the 
internal  maxillary  artery. 

INTERNAL  MAX-  This  is  the  larger  of  the  two  terminal  branches 
ILLARY  AHTERT.  into  which  the  external  carotid  divides  opposite  the 
neck  of  the  jaw.  It  passes  horizontally  forwards  between  the  neck 
of  the  jaw  and  the  internal  lateral  ligament,  then  runs  tortuously, 
in  some  cases  above,  in  others  beneath  the  external  pterygoid, 
enters  the  Bpheno-maxillary  fossa  between  the  two  heads  of  the 


100 


INTERNAL  MAXILLARY  ARTERY. 


external  pterygoid,  and  terminates  by  dividing  into   numerous 
branches. 

The  course  of  this  artery  is  divided  into  three  stages.  In  the 
first,  the  artery  lies  between  the  neck  of  the  jaw  and  the  internal 
lateral  ligament ;  in  the  second,  it  lies  either  over  or  under 
the  external  pterygoid ;  in  the  third,  it  lies  in  the  spheno-maxillary 
fossa. 


BEANCHES  OF  THE  INTERNAL  MAXILLARY  ARTERY  IN  THE  THREE 
STAGES   OF  ITS   COURSE. 


BRANCHES  IN  THE  FIBST 
STAGE. 

a.  Tympanic. 

b.  Meningea  media. 

c.  Meningea  parva. 

d.  Inferior  dental. 


BRANCHES  IN  THE  SECOND 
STAGE. 

Six  to  the  five   muscles   of 
mastication,  namely : 
f.  Masseteric. 

f.  Anterior  and  posterior 

temporal. 

g.  External  and  internal 

pterygoid. 
h.  Buceal. 


BRANCHES  IN  THE  THIRD 

STAGE. 

t.   Superior  dental. 
j.  Infra-orbital. 
k.  Descending  palatine. 
I.   Vidian. 

m.  Ptery go-palatine. 
n.  Nasal  or  spheno-pala- 
tine. 


BRANCHES  m  a.  The  tympanic  ascends  behind  the  articulation  of 

THE  FIRST  PART.  the  jaw,  and  passes  through  the  Glaserian  fissure  to  the 
tympanum.  It  supplies  that  cavity  and  the  membrana  tympani,  and 
anastomoses  with  the  stylo-mastoid  and  "Vidian  arteries.  This  artery 
is  not  infrequently  given  off  from  a  branch  of  the  internal  maxillary 
artery. 

b.  The  middle  meningeal  artery  ascends  between  the  two  roots  of 
the  auriculo-temporal  nerve,  behind  the  external  pterygoid,  and  enters 
through   the   foramen   spinosum   into   the   cranium,  where   it   ramifies 
between  the  dura  mater  and  the  bones.     Its  further  course  is  described 
at  p.  12. 

c.  The  meningea  parva  (not  marked  in  the  plan)  ascends  through  the 
foramen  ovale  into  the  skull,  and  supplies  chiefly  the  ganglion  of  the  fifth 
pair.     It  often  comes  from  the  meningea  media. 

d.  The  inferior  dental  artery  descends  behind  the  neck  of  the  jaw  to 
the  dental  foramen,  which  it  enters  with  the  dental  nerve.     It  then  pro- 


INTERNAL  MAXILLAET  ARTERY. 


101 


ceeds  through  a  canal  in  the  diploe  to  the  symphysis,  where  it  minutely 
inosculates  with  its  fellow.  In  this  canal,  which  runs  beneath  the  roots 
of  all  the  teeth,  the  artery  gives  branches  which  ascend  through  the  little 
foramina  in  the  fangs,  and  supply  the  pulp  in  their  interior.  Opposite 
the  foramen  mentale  arises  the  mental  branch  already  described  (p.  94). 
Before  entering  the  dental  foramen  the  artery  furnishes  a  small  branch — 
mylo-hyoid — •  which  accompanies  the  nerve  proceeding  to  the  mylo-hyoid 
muscle. 

BEANCHES  IN  e.  The  masseteric  branch  passes  through  the  sigmoid 

THE  SECOND  PART,  notch  of  the  jaw  to  the  under  surface  of  the  masseter, 
with  the  masseteric  nerve,  and  inosculates  with  the  facial  artery. 

FIG.  17. 


Third  stage.  Second  stage.  First  stage. 

PLAN    OF   INTERNAL   MAXILLARY    ARTERY. 


f.  The  anterior  and  posterior  temporal  arteries  ascend  to  supply  the 
temporal  muscle,  ramifying  between  the  muscle  and  the  bone,  one  near 
the  front,  the  other  near  the  posterior  border  of  the  muscle.  They  com- 
municate with  the  superficial  and  middle  temporal  arteries,  and  with  the 
terminal  branches  of  the  lachrymal  a. 

g.  The  pterygoid  branches  supply  the  internal  and  external  pterygoid 
muscles. 

h.  The  buccal  branch  runs  forward  with  the  buccal  nerve  to  the 
buccinator,  where  it  anastomoses  with  the  facial  artery. 


102  INTERNAL   MAXILLARY   ARTERY. 

BEANCHES  IN  i.  The  superior  dental  branch  runs  along  the  tube- 

fHE  THIRD  PAET.  rosity  of  the  superior  maxillary  bone,  and  sends  small 
arteries  through  the  foramina  in  the  bone  to  the  pulps  of  the  molar  and 
bicuspid  teeth.  It  also  supplies  the  gums,  and  the  mucous  membrane  of 
the  antrum. 

j.  The  infra-orbital  branch  ascends  through  the  spheno-maxillary 
fissure,  then  runs  forward  along  the  infra-orbital  canal  with  the  superior 
maxillary  nerve,  and  emerges  upon  the  face  at  the  infra-orbital  foramen. 
In  the  infra-orbital  canal  the  artery  sends  branches  downwards  through 
little  canals  in  the  bone  to  the  incisor  and  canine  teeth,  and  upwards  into 
the  orbit  to  the  inferior  oblique  and  inferior  rectus.  After  issuing  from 
the  foramen  it  sends  upward  branches  to  the  lachrymal  sac,  and  descending 
branches  to  the  upper  lip.  The  former  anastomose  with  the  nasal 
branches  of  the  ophthalmic  and  facial  arteries;  the  latter  with  the 
superior  coronary,  transverse  facial,  and  buccal  arteries. 

k.  The  descending  palatine,  a  branch  of  considerable  size,  runs  down 
the  posterior  palatine  canal  with  the  palatine  nerve  (a  branch  from 
Meckel's  ganglion),  and  then  along  the  roof  of  the  hard  palate,  towards 
the  anterior  palatine  canal,  in  which,  much  diminished  in  size,  it  inoscu- 
lates on  the  septum  nasi  with  a  branch  of  the  spheno-palatine  artery. 
It  supplies  the  gums,  the  glands,  and  mucous  membrane  of  this  part,  and 
furnishes  branches  to  the  soft  palate. 

I.  The  Vidian,  an  insignificant  branch,  runs  backwards  through  the 
Vidian  canal  with  the  Vidian  nerve,  and  is  distributed  to  the  Eustachian 
tube,  the  pharynx,  and  the  tympanum. 

TO.  The  ptery go-palatine  is  a  small  but  constant  branch  which  runs 
backwards  through  the  pterygo  palatine  canal,  and  ramifies  upon  the 
upper  part  of  the  pharynx  and  the  Eustachian  tube. 

n.  The  nasal  or  spheno-palatine  branch  enters  the  nose  through  the 
spheno-palatine  foramen  in  company  with  the  nasal  nerve  from  Meckel's 
(spheno-palatine)  ganglion,  and  ramifies  upon  the  spongy  bones,  the 
ethmoidal  cells,  and  the  antrum.  One  large  branch,  the  artery  of  the 
septum,  runs  along  the  septum  nasi  towards  the  anterior  palatine  canal, 
where  it  joins  the  descending  palatine  a. 

Observe  that  all  the  branches  of  the  internal  maxillary  artery 
in  the  first  and  third  parts  of  its  course  traverse  bony  canals ;  while 
the  branches  in  the  second  part  go  directly  to  muscles. 

The  internal  maxillary  vein  is  formed  by  the  veins  correspond- 


INFERIOR   MAXILLARY   NERVE.  103 

ing  to  the  branches  of  the  artery.     As  the  vein  lies  between  the 
PTERTGOID  temporal  and  external  pterygoid  muscles  it  forms 

PLEXUS  OF  VEINS.  a  plexus — pterygoid  plexus — which  communi- 
cates, above,  with  the  cavernous  sinus  by  branches  which  come 
through  the  foramina  at  the  base  of  the  skull ;  in  front  it  communi- 
cates with  the  facial  vein.  It  joins  the  temporal  in  the  substance 
of  the  parotid  gland,  and  thus  communicates  with  the  external 
jugular  vein. 

INFERIOR  MAX-  This  great  nerve  is  the  largest  of  the  three 
ILLARY  NERVE  divisions  of  the  fifth  cerebral  nerve.  It  differs 
AND  BRANCHES.  from  the  other  two  divisions,  i.e.  the  ophthalmic 
and  the  superior  maxillary,  in  that  it  contains  motor  as  well  as 
sensory  filaments  ;  the  motor  being  furnished  by  the  small  non- 
ganglionic  root  of  the  fifth  nerve.  It  is  necessary  to  remember  this 
point  of  its  physiology,  in  order  to  understand  its  extensive  dis- 
tribution ;  for  the  sensory  portion  supplies  the  parts  to  which  it  is 
distributed  with  common  sensation  only,  whilst  the  motor  portion 
supplies  all  the  muscles  concerned  in  mastication. 

The  nerve,  then,  composed  of  sensory  and  motor  filaments, 
emerges  from  the  skull  through  the  foramen  ovale  as  a  thick 
trunk,  under  the  name  of  the  inferior  maxillary.  It  lies  directly 
external  to  the  Eustachian  tube,  and  is  covered  by  the  external 
pterygoid  muscle,  which  must  be  turned  on  one  side  to  expose  it. 
Immediately  after  its  exit  from  the  skull,  the  nerve  divides  into 
two  parts,  an  anterior,  or  motor  division,  and  a  posterior  or  sen- 
sory division.  From  the  anterior  portion  (chiefly  motor)  are 
derived  branches  distributed  to  the  muscles  of  mastication.  From 
the  posterior  (mainly  sensory)  come  the  following  branches :  the 
auriculo-temporal,  gustatory,  inferior  dental  and  buccal ;  there 
are  also  motor  branches  to  the  mylo-hyoid  and  anterior  belly 
of  the  digastricus.  This  apparent  anomaly  will  be  presently 
explained. 


104  INFERIOR   MAXILLARY   NERVE. 


BRANCHES  OF  THE  INFERIOR  MAXILLARY  NERVE. 

SENSOET  BRANCHES.  MOTOK  BRANCHES. 

Auriculo-temporal.  To  temporal  muscle. 

Inferior  dental.  —  masseter. 

Buccal.  —  external  pterygoid. 

Gustatory  or  lingual.  —  internal  pterygoid. 

—  mylo-hyoideus. 

—  anterior  belly  of  digastricus. 

The  branches  to  the  temporal  muscle,  two  in  number,  ante- 
rior and  posterior,  pass  outwards  close  to  the  great  wing  of  the 
sphenoid  bone,  and  ascend  with  the  temporal  arteries  to  the 
muscle. 

The  branch  to  the  masseter  runs  outwards  above  the  external 
pterygoid,  through  the  sigmoid  notch  of  the  jaw,  to  the  under 
surface  of  the  muscle. 

The  branch  to  the  external  pterygoid  comes,  apparently,  from 
the  buccal  nerve  in  its  passage  through  this  muscle. 

The  branch  to  the  internal  pterygoid  muscle  proceeds  from 
the  inner  side  of  the  main  trunk,  close  to  the  otic  ganglion,  and 
descending  between  the  internal  pterygoid  and  the  tensor  palati, 
enters  the  inner  aspect  of  the  muscle. 

The  buccal  branch  passes  either  above  or  between  the  fibres  of 
the  external  pterygoid  to  the  buccinator,  where  it  spreads  out  into 
filaments,  which  supply  the  skin,  mucous  membrane,  and  glands 
of  the  cheek  with  common  sensation.  The  motor  power  of  the 
buccinator,  remember,  is  derived  from  the  facial  nerve.  That 
this  buccal  branch  is  mainly  sensory  is  proved  by  the  action  of  the 
muscle  still  continuing  when  the 'motor  division  of  the  fifth  nerve 
is  paralysed.  The  evidence  is  corroborated  by  a  case  in  which 
this  buccal  branch  proceeded  from  the  second  division  of  the 
fifth  nerve ;  no  communication  being  discovered,  after  very 


INFERIOR    MAXILLARY    NERVE. 


105 


careful  dissection,  between  it  and  the  motor  root  of  the  third 
division.* 

The  auriculo-temporal  branch  arises  by  two  roots  which  em- 
brace the  middle  meningeal  artery  before  it  enters  the  skull.  The 
nerve  runs  outwards  behind  the  external  pterygoid  and  the  neck 
of  the  jaw,  ascends  over  the  root  of  the  zygoma  with  the  temporal 
artery,  and  divides,  like  it,  into  an  anterior  and  a  posterior  branch  : 
these  are  distributed  to  the  skin  of  the  side  of  the  head.  Behind 

FIG.  18. 


PLAN    OF   THE    BRANCHES    OF   THE    INFERIOR    MAXILLARY    NERVE. 

the  condyle  it  sends  filaments  to  the  meatus  auditorius,  to  the 
gkin  on  the  outer  aspect  of  the  ear,  and  to  the  articulation  of  the 
jaw.  It  distributes  also  filaments  to  the  parotid  gland,  and  one 

*  Turner,  '  On  the  Variation  of  the  Buccal  Nerve.'     '  Journal  of  Anat.  and  Phys.,' 
No.  I.  1866. 


106  INFERIOB   MAXILLAEY   NERVE. 

especially  to  the  upper  division  of  the  facial,  which  endows  it 
with  common  sensibility  :  its  branches  have  been  described  (p.  95). 
The  inferior  dental  branch  emerges  beneath  the  external  ptery- 
goid,  and  descends  between  the  ramus  and  the  internal  lateral 
ligament  of  the  jaw  to  the  dental  foramen,  which  it  enters  with 
the  dental  artery.  It  then  runs  in  the  canal  in  the  diploe  of  the 
jaw  and  furnishes  filaments  which  ascend  through  the  canals  in 
the  fangs  of  the  teeth  to  the  pulp  in  their  interior.  Opposite  the 
foramen  mentale  it  divides  into  two  branches,  the  mental  and 
incisor.  Observe  that  the  same  nerve  which  supplies  the  teeth 
supplies  the  gums ;  hence  the  sympathy  between  them. 

a.  The  mylo-hyoid  branch,  apparently  arising  from  the  dental,  is 
derived  from  the  motor  root  of  the  fifth,  and  may,  with  careful  dissection, 
be  traced  to  it.    It  leaves  the  sheath  of  the  inferior  dental  nerve  near  the 
foramen  in  the  jaw,  and  runs  in  a  groove  on  the  inner  side  of  the  ramus 
to  the  lower  surface  of  the  mylo-hyoid,  which  muscle,  together  with  the 
anterior  portion  of  the  digastricus,  it  supplies. 

b.  The  dental  branches  pass  upwards  to  the  fangs  of  the  molar  and 
bicuspid  teeth. 

c.  The  incisor  branch  is  the  continuation  of  the  nerve,  and  passes  to 
the  symphysis,  supplying  the  canine  and  incisor  teeth. 

d.  The  mental  branch  (sometimes  called  labial)  emerges  through  the 
foramen    mentale,    and    soon    divides   into    numerous  branches;    some 
ascend  to  the  lower  lip  beneath  the  depressor  labii  inferioris,  and  com- 
municate with  the  facial  nerve ;    others  pass  inwards  to  the  skin  of 
the  chin. 

The  gustatory  or  lingual  nerve  lies  at  first  behind  the  external 
pterygoid  m.,  then  descends  obliquely  forwards  between  the  ramus 
of  the  jaw  and  the  internal  pterygoid  m.,  and  subsequently  for  a 
short  distance  between  the  jaw  and  the  superior  constrictor  of  the 
pharynx.  Here  it  lies  close  under  the  mucous  membrane  of  the 
mouth  near  the  last  molar  tooth  of  the  lower  jaw.  Division  of 
it  in  this  situation  has  relieved  pain  in  cancer  of  the  tongue.  The 
gustatory  n.  then  rests  upon  the  stylo-glossus  and  the  hyo-glossus 
m.,  and  after  crossing  Wharton's  duct  passes  to  the  tip  of  the 
tongue. 


INTERNAL  LATERAL  LIGAMENT.  107 

The  nerve  at  first  lies  in  front  of  the  inferior  dental  nerve 
(with  which  it  is  frequently  connected),  and  beneath  the  internal 
maxillary  a.  Beneath  the  external  pterygoid  the  gustatory  n.  is 
joined  at  an  acute  angle  by  the  chorda  tympani  (a  branch  of  the 
facial).  This  branch  emerges  through  the  Glaserian  fissure,  or 
through  a  small  canal  by  the  side  of  it,  and  passing  behind  the 
dental  n.,  meets  the  gustatory,  and  runs  along  the  lower  border  of 
this  nerve  to  join  the  submaxillary  ganglion.  It  is  eventually 
distributed  to  the  lingualis  muscle. 

The  gustatory  in  its  course  gives  off : 

a.  Communicating  branches  to  the  hypoglossal  n.,   forming  two  or 
more  loops  at  the  anterior  border  of  the  hyo-glossus. 

b.  Branches  to  the  submaxillary  ganglion. 

c.  Branches  to  the  mucous  membrane  of  the  mouth,  gums,  and  sub- 
lingual  gland. 

d.  Branches  which  pass  to  the  papillae  of  the  sides  and  tip  of  the 
tongue :  here  also  we  find  communications  between  this  nerve  and  the 
hypoglossal. 

INTERNAL  This  so-called  ligament  (which  is  more  like  a 

LATERAL  LIGA-  layer  of  fascia)  passes  from  the  spinous  process 
MKNTOFTHE  of  the  sphenoid  bone  to  the  inner  side  of  the 

foramen  dentale.  Between  this  ligament  and  the 
neck  of  the  jaw,  we  find  the  internal  maxillary  artery  and  vein, 
the  auriculo-temporal  nerve,  the  middle  meningeal  artery,  the 
dental  nerve  and  artery,  and  a  portion  of  the  parotid  gland. 

At  this  stage  of  the  dissection  you  will  be  able  to  trace  the 
course  and  relations  of  the  internal  carotid  artery.  But  before 
doing  this,  examine  the  several  objects  which  intervene  between 
the  external  and  internal  carotids.  These  are — :1.  The  stylo- 
glossus  :  2.  The  stylo-pharyngeus  :  3.  The  glosso-pharyngeal 
nerve  :  4.  The  stylo-hyoid  ligament. 

This  arises  from  the  styloid  process  near  the 
STYLO-GLOSSUS.  j     .-,          ,    i  MI  T  j    • 

apex,  and   the   stylo-maxillary  ligament,  and  is 

inserted  along  the  side  of  the  tongue,  external  to  the  hyo-glossus. 
Its  action  is  to  retract  the  tongue.  Its  nerve  is  a  branch  of  the 
hypoglossal. 


108  GLOSSO-PHARYNGEAL   NERVE. 

STYLO-  This  arises  from  the  inner  side  of  the  styloid 

PHABYNGEUS.  process  near  the  base,  and  is  inserted  into  the 

upper  and  posterior  edges  of  the  thyroid  cartilage.  It  descends 
along  the  side  of  the  pharynx  between  the  superior  and  the 
middle  constrictors.  Curving  round  its  lower  border  is  seen  the 
glosso-pharyngeal  nerve.  Its  nerve  comes  from  the  pharyngeal 
plexus.  Its  action  is  to  raise  the  larynx  with  the  pharynx  in 
deglutition. 

Between  the  stylo-glossus  and  stylo-pharyngeus,  and  nearly 
parallel  with  both,  is  the  stylo-hyoid  ligament.  It  extends  from 
the  apex  of  the  styloid  process  to  the  lesser  cornu  of  the  os  hyoides. 
It  is  often  more  or  less  ossified. 

The  ascending  palatine  artery,  a  branch  of  the  facial  (p.  45), 
runs  up  between  the  stylo-glossus  and  the  stylo-pharyngeus,  and 
divides  into  branches  which  supply  these  muscles,  the  palate,  the 
side  of  the  pharynx,  and  the  tonsils.  It  inosculates  with  the 
descending  palatine,  a  branch  of  the  internal  maxillary. 

The  glosso-pharyngeal  nerve  is  observed  curving 
forwards   under    the    lower  border  of  the  stylo- 

RYNGEAL  NERVE.  J 

pharyngeus  (p.  48).  It  is  one  of  the  divisions 
of  the  eighth  pair,  arises  by  five  or  six  filaments  from  the  resti- 
form  tract  of  the  medulla  oblongata,  leaves  the  skull  through  the 
anterior  part  of  the  foramen  jugulare  in  a  separate  sheath  of 
dura  mater,  in  front  of  the  remaining  divisions  of  the  eighth 
pair,  and  descends  between  the  internal  jugular  vein  and  the 
internal  carotid  artery.  It  then  crosses  in  front  of  the  artery  and 
proceeds  along  the  lower  border  of  the  stylo-pharyngeus.  At  this 
point,  it  curves  forwards  over  that  muscle  and  the  middle  con- 
strictor of  the  pharynx,  and  disappears  beneath  the  hyo-glossus, 
where  it  divides  into  its  terminal  branches,  which  supply  the 
mucous  membrane  of  the  pharynx,  the  back  of  the  tongue,  and  the 
tonsils. 

The  glosso-pharyngeal  is  regarded,  at  its  origin,  as  purely  a 
sensory  nerve.  But  soon  after  its  exit  from  the  skull  it  receives 
communications  from  the  facial,  the  pneumogastric,  and  the 
sympathetic,  so  that  it  soon  becomes  a  compound  nerve  — i.e. 


INTERNAL  CAROTID  ARTERY.  109 

composed  of  both  sensory  and  motor  filaments.  At  the  base  of 
the  skull  it  presents  two  ganglia — the  jugular  and  the  petrous 
(ganglion  of  Andersch).  The  branches  given  off  by  these  ganglia 
will  be  dissected  hereafter ;  at  present  the  student  can  only 
make  out  the  branches  which  this  nerve  gives  off  in  the  neck, 
namely : 

Carotid  branches,  which  surround  the  internal  carotid  artery,  and 
communicate  with  the  pharyngeal  branch  of  the  pneumogastric  and  with 
the  sympathetic. 

Pharyngeal  branches,  which  form  by  the  side  of  the  middle  constrictor 
of  the  pharynx,  a  plexus,  the  pharyngeal  plexus,  supplemented  by 
filaments  derived  from  the  pneumogastric,  the  nervus  accessorius,  the 
external  laryngeal,  and  the  sympathetic.  Its  branches  supply  the 
constrictor  muscles  and  the  mucous  membrane  of  the  pharynx,  the 
back  of  the  tongue,  and  the  tonsils. 

Muscular  branches  which  enter  the  stylo-pharyngeus  m. 

Tonsillar  branches  which  are  given  to  the  soft  palate  and  the  tonsils 
forming  a  plexus  (circulus  tonsillaris). 

Lingual  branches,  which  are  distributed  to  tbe  base  and  lateral 
aspects  of  tbe  tongue. 

The  styloid  process  must  now  be  cut  through  at  its  base,  and 
turned  forwards  with  the  muscles  arising  from  it.  The  internal 
carotid  artery  will  thus  be  exposed  in  the  cervical  region,  as  far  as 
the  carotid  canal.  The  part  of  the  artery  contained  within  the 
carotid  canal  will  be  described  hereafter. 

The  internal  carotid  artery  proceeds  from  the 
CAEOTID  AKTEBT.  bifurcation  of  the  common  carotid  at  the  upper 
border  of  the  thyroid  cartilage,  and  ascends  to  the 
base  of  the  skull  by  the  side  of  the  pharynx,  close  to  the  trans- 
verse processes  of  the  three  upper  cervical  vertebrae.  It  enters 
the  skull  through  the  carotid  canal  in  the  temporal  bone,  runs 
tortuously  by  the  side  of  the  body  of  the  sphenoid,  and  terminates 
in  branches  which  supply  the  orbit  and  the  brain.  In  the  cervical 
part  of  its  course,  it  is  situated  immediately  to  the  outer  side  of 
the  external  carotid  artery,  behind  the  inner  border  of  the  sterno- 
mastoid.  It  soon  gets  beneath  the  external  carotid,  and  lies  deeply 


110  PNEUMOGASTRIC   NERVE. 

seated  by  the  side  of  the  pharynx  and  tonsil.  It  lies  upon  the 
rectus  capitis  anticus  major,  the  superior  laryngeal,  sympathetic, 
and  pneumogastric  nerves.  It  is  crossed,  successively,  by  the 
hypoglossal  nerve,  the  occipital  artery,  the  digastricus  and  stylo- 
hyoid  muscles  ;  higher  up  it  is  crossed  obliquely  by  the  styloid 
process,  the  stylo-glossus  and  stylo-pharyngeus  muscles,  by  the 
glosso-pharyngeal  nerve,  and  the  stylo-hyoid  ligament,  all  of 
which  last-named  structures  intervene  between  it  and  the  external 
carotid.  On  the  outer  side  of  the  artery  is  the  internal  jugular 
vein  ;  and  on  the  inner,  the  pharynx,  the  tonsil,  and  the  ascending 
pharyngeal  artery. 

The  most  important  relation  of  the  artery,  in  a  surgical  point 
of  view,  is,  that  it  ascends  close  by  the  side  of  the  pharynx  and 
tonsil.  In  opening  an  abscess,  therefore,  near  the  tonsil,  or  at 
the  back  of  the  pharynx,  be  careful  to  introduce  the  knife  with 
its  point  inwards  towards  the  mesial  line :  observe  this  caution 
the  more,  because,  in  some  subjects,  the  internal  carotid  makes  a 
curve,  or  even  a  complete  curl  upon  itself,  in  its  ascent  near  the 
pharynx.  In  such  cases  an  undue  deviation  of  the  instrument  in 
an  outward  direction  would  injure  the  vessel. 

ASCENDING  This  artery  generally  arises  from  the  external 

PHARYNGEAL  carotid  about  half  an  inch  above  the  angle  of  the 

AETERY.  common  carotid.     It  ascends  in  a  straight  course 

between  the  internal  carotid  artery  and  the  side  of  the  pharynx, 
towards  the  base  of  the  skull,  resting  upon  the  rectus  capitis 
anticus  major.  It  gives  off  branches  which  supply  the  pharynx, 
the  tonsil,  the  Eustachian  tube,  and  the  muscles  in  front  of  the 
spine.  A  very  constant  branch,  the  palatine,  runs  down  with  the 
levator  palati,  above  the  superior  constrictor  of  the  pharynx,  and 
supplies  the  soft  palate.  It  also  sends  small  meningeal  branches 
to  supply  the  dura  mater ;  one  of  which  ascends  through  the 
foramen  lacerum  medium,  another  through  the  foramen  jugulare 
with  the  internal  jugular  vein. 

PNHUMOGASTKIC  The  pneumogastric  nerve  is  the  largest  and 

NBRVB.  longest  of  the  three  divisions  of  the  eighth  pair  of 


PNEUMOGASTRIC    NERVE.  Ill 

cerebral  nerves.  It  arises  from  the  medulla  oblongata  by  a  series 
of  roots,  twelve  to  fifteen  in  number,  along  the  restiform  tract. 
It  passes  out  of  the  skull  in  a  common  sheath  with  the  nervus 
accessorius  through  the  foramen  jugulare. 

Leaving  the  skull  at  the  foramen  jugulare,  the  nerve  descends 
in  front  of  the  cervical  vertebra,  lying  successively  upon  the 
rectus  capitis  anticus  major  and  the  longus  colli.  In  the  upper 
part  of  the  neck  it  is  situated  behind  the  internal  carotid  artery  : 
lower  down,  it  lies  between  and  behind  the  common  carotid  and 
the  internal  jugular  vein.  It  enters  the  chest,  on  the  right  side, 
crossing  in  front  of  the  subclavian  artery  nearly  at  a  right  angle  ; 
on  the  left,  running  nearly  parallel  with  it. 

In  their  course  through  the  chest,  the  pneumogastric  nerves 
have  not  similar  relations.  The  right  nerve  lies  beneath  the  subcla- 
vian vein,  and  then  descending  behind  the  right  brachio-cephalic 
vein  by  the  side  of  the  trachea,  is  continued  behind  the  right 
bronchus  to  the  posterior  part  of  the  oesophagus.  The  left  nerve 
passes  behind  the  left  brachio-cephalic  vein,  then  crosses  in  front 
of  the  arch  of  the  aorta,  and  behind  the  left  bronchus  to  the 
anterior  part  of  the  oesophagus.  Both  nerves  subdivide  on  the 
oesophagus  into  a  plexus ;  the  right  nerve  forming  the  posterior 
cesophageal  plexus,  the  left  the  anterior.  Each  plexus  again 
collects  its  fibres  together  to  form  a  single  trunk  :  thus  two  main 
nerves  are  formed  which  pass  with  the  oesophagus  through  the 
diaphragm :  of  these  the  right  is  distributed  over  the  posterior, 
the  left  over  the  anterior  surface  of  the  stomach.* 

In  their  long  course  from  the  medulla  oblongata  to  the  abdo- 
men, the  pneumogastric  nerves  supply  branches  to  most  important 
organs  ;  namely,  to  the  pharynx,  the  larynx,  the  heart,  the  lungs, 
the  oesophagus,  the  stomach,  and  the  liver. 

Within  the  foramen  jugulare  a  small  ganglion — ganglion  of 
the  root — (Arnold's  ganglion)  is  situated  upon  the  pneumogastric 

*  The  differences  in  the  course  and  destination  of  the  right  and  the  left  pneumo- 
gastric nerves  may  be  explained  in  the  process  of  development.  The  student  is 
therefore  referred  to  works  which  treat  of  this  subject. 


112  PNEUMOGASTRIC    NERVE. 

nerve,  and  is  joined  by  a  branch  from  the  nervus  accessorius. 
This  ganglion  will  be  described  hereafter.  About  half  an  inch 
below  the  preceding  the  pneumogastric  nerve  swells  out,  and  forms 
a  second  ganglion — ganglion  of  the  trunk — (inferior  ganglion)  of 
a  reddish-grey  colour.  This  ganglion  occupies  about  an  inch  of 
the  nerve,  but  does  not  involve  the  whole  of  its  fibres ;  the  branch 
from  the  spinal  accessory  not  being  included.  It  is  united  to  the 
hypoglossal  nerve,  from  which  it  receives  filaments.  It  also 
receives  filaments  from  the  first  and  second  spinal  nerves,  and  from 
the  superior  cervical  ganglion  of  the  sympathetic. 

Thus,  the  pneumogastric,  at  its  origin  probably  a  nerve  of 
sensation  only,  becomes,  in  consequence  of  the  connecting  filaments 
from  these  various  branches,  a  compound  nerve,  and  in  all  respects 
analogous  to  a  spinal  nerve. 

The  branches  of  distribution  of  the  pneumogastric  are  : 

a.  The  auricular  (Arnold),  which  cannot  at  present  be  seen, 
will  be  made  out  in  the  dissection  of  the  eighth  pair  at  the  base 
of  the  skull. 

6.  The  pharyngeal  arises  from  the  upper  part  of  the  ganglion 
of  the  trunk,  and  descends  either  in  front  of  or  behind  the  inter- 
nal carotid.  The  nerve,  after  passing  the  inner  side  of  the  internal 
carotid,  divides  into  branches,  which  with  the  other  filaments 
(described  p.  109)  upon  the  middle  constrictor  muscle  form  the 
pharyngeal  plexus.  From  this  plexus  branches  are  distributed 
to  the  muscles  and  the  mucous  membrane  of  the  pharynx. 

c.  The  superior  laryngeal,  derived  from  the  middle  of  the 
ganglion  of  the  trunk,  descends  behind  the  internal  carotid, 
and  divides  into  two  branches,  the  internal  and  the  external 
laryngeal. 

The  internal  laryngeal  passes  to  the  interval  between  the  os  hyoides 
and  the  thyroid  cartilage,  and  enters  the  larynx  (with  the  superior 
laryngeal  a.),  through  the  thyro-hyoid  membrane  to  be  distributed  to  the 
mucous  membrane  of  the  larynx  and  epiglottis.  The  external  laryngeal, 
the  smaller,  gives  off  some  branches  to  the  pharyngeal  plexus  and  the 
inferior  constrictor,  and  then  descends  beneath  the  depressors  of  the  os 
hyoides  to  supply  the  crico-thyroid  muscle. 


PNEUMOGASTRIC    NERVE.  113 

d.  The  cervical  cardiac  branches,  upper  and  lower,  descend 
behind  the  sheath  of  the  carotid  artery  to  the  cardiac  plexus.    The 
upper  branch  is  small  and  proceeds  from  the  ganglion  of  the  trunk ; 
the  lower  comes  from  the  trunk  of  the  pneumogastric  before  it 
enters  the  chest.      Subsequently,  the  right  lower  cardiac  nerve 
descends  with  the  innominate  artery  to  join  the  deep  cardiac  plexus ; 
the  left  passes  over  the  arch  of  the  aorta  to  join  the  superficial 
cardiac  plexus. 

e.  The   inferior  or  recurrent  laryngeal  nerve  turns,  on  the 
right    side,    under   the    subclavian    artery    (p.  61),    and   ascends 
obliquely  inwards  to  the  larynx  behind  the  common  carotid  and 
the   inferior  thyroid    arteries :    it  lies    subsequently    behind    the 
trachea.     On  the  left  side,  it  tunas  under  the  arch   of  the  aorta, 
just  on  the  outer  side  of  the  remains  of   the  'ductus  arteriosus;' 
after  which  it  runs  up  between  the  trachea  and  the  oesophagus.  On 
both  sides  the  nerves  enter  the  larynx  beneath  the  lower  border 
of  the  inferior  constrictor,  and  supply  all  the  intrinsic  muscles 
of  the   larynx,   except  the  crico-thyroid.     These  nerves  as  they 
turn   under   their   respective    vessels   give    off  branches    to   the 
deep  cardiac  plexus. 

The  remaining  branches  of  the  pneumogastric  nerve  to  the 
lungs,  heart,  oesophagus  and  stomach  will  be  examined  in  the 
dissection  of  the  chest. 

SPINAL  ACCES-          The  spinal  accessory  nerve  issues  through  the 
SOKT  NERVE.  anterior  part  of  the  foramen  jugulare,  in  a  sheath 

of  dura  mater  common  to  it  and  the  pneumogastric  nerve.  It 
arises  by  numerous  filaments  from  the  medulla  oblongata,  below 
the  pneumogastric,  and  from  the  lateral  column  of  the  spinal 
cord  as  low  down  as  the  sixth  cervical  vertebra.  These  roots  con- 
verge to  the  jugular  foramen,  where  the  nerve  consists  of  two 
portions :  one  of  which,  the  internal  or  accessory,  joins  the 
pneumogastric  ;  the  other,  the  external  or  spinal,  is  distributed 
to  muscles. 

The  accessory  part,  within  the  foramen  jugulare,  sends  one  or 
more  filaments  to  the  ganglion  of  the  root  of  the  pneumogastric. 
It  lies  close  to  the  pneumogastric  nerve  at  the  ganglion  of  the 

i 


114  SYMPATHETIC    NERVE    IN    THE    NECK. 

trunk,  and  is  finally  incorporated  with  the  nerve  below  the 
ganglion. 

The  spinal  part  separates  from  the  accessory  part  below  the 
foramen  jugulare.  It  then  takes  a  curved  course  backwards  and 
outwards,  lying  in  front  of  the  transverse  process  of  the  atlas, 
and,  after  supplying  the  sterno-mastoid  muscle,  is  distributed  to 
the  trapezius. 

HYPOGLOSSAL  This  nerve  passes  through  the  anterior  condy- 

NERVE.  ioj(j  foramen  in  two  fasciculi  which  join  outside 

the  skull.  The  nerve  comes  forward  between  the  internal  jugu- 
lar vein  and  the  internal  carotid  artery,  and  then  winds  round 
the  occipital  artery.  Its  further  course  has  been  described 
(p.  49). 

At  the  base  of  the  skull  it  gives  off  several  filaments  which 
connect  it  with  the  ganglion  of  the  trunk  of  the  pneumogastric 
nerve.  These  two  nerves  are  sometimes  almost  inseparably 
united.  It  gives  off  also  several  delicate  filaments  to  the  superior 
cervical  ganglion  of  the  sympathetic,  and  communicates  with 
the  loop  formed  by  the  first  two  spinal  nerves  in  front  of  the 
atlas. 

SYMPATHETIC  Now  examine  the  cervical  ganglia  of  the  sym- 

NKHVE.  pathetic  system  of  nerves.     This  '  system '  consists 

of  a  series  of  ganglia  arranged  on  each  side  of  the  spine,  from  the 
first  cervical  to  tne  last  sacral  vertebra.  The  successive  ganglia 
of  the  same  side  are  connected  by  intermediate  nerves,  so  as  to  form 
a  continuous  cord  on  each  side  of  the  spine  :  this  constitutes  what 
is  called  the  trunk  of  the  sympathetic  system,  and  is  connected 
with  all  the  spinal  nerves.  Its  upper  or  cephalic  extremity  enters 
the  cranium  through  the  carotid  canal,  surrounds  the  internal 
carotid  artery,  communicates  with  the  third,  fourth,  fifth,  and 
sixth  cranial  nerves,  and  joins  its  fellow  of  the  opposite  side  upon 
the  anterior  communicating  artery.*  Its  sacral  extremity  joins 
its  fellow  by  means  of  a  little  ganglion  impar,  situated  in  the 
mesial  line,  upon  the  coccyx. 

*  Here  is  situated  the  so-called  ganglion  of  Ribes. 


SYMPATHETIC  NERVE  IN  THE  NECK.  115 

The  ganglia,  as  already  stated,  are  connected  with  the  spinal 
nerves ;  this  connection  takes  place  by  two  filaments — one  of 
white  nerve-fibre  which  passes  from  the  spinal  nerve  to  the 
ganglion,  the  other,  of  grey,  from  the  ganglion  to  the  spinal 
nerve. 

The  different  portions  of  the  sympathetic  gangliated  cord 
receive,  respectively,  the  distinguishing  names  of  the  cervical, 
dorsal,  lumbar,  and  sacral.  At  present  we  have  only  to  consider 
the  cervical  portion  of  it. 

To  expose  the  cervical  portion  of  the  sympathetic,  the  internal 
carotid  artery,  the  pneumogastric,  glosso-pharyngeal,  and  hypo- 
glossal  nerves  should  be  cut  through  near  the  base  of  the  skull ; 
then  by  careful  dissection  the  superior  cervical  ganglion  can  be 
traced  out. 

CERVICAL  GAN-  ^n  tne  cervical  portion  of  the  sympathetic  are 
GLIA  OF  SYMPA-  three  ganglia,  named  from  their  position,  superior, 
THETIC.  middle,  and  inferior. 

The  superior  cervical  ganglion,  the  largest  of  the  three,  is 
situated  near  the  base  of  the  skull,  opposite  the  second  and 
third  cervical  vertebrae,  and  lies  behind  and  on  the  inner  side  of 
the  internal  carotid  artery,  upon  the  rectus  capitis  anticus  major. 
It  is  of  a  reddish-grey  colour  like  the  other  ganglia,  of  an  elongated 
oval  shape,  varying  in  length  from  one  to  two  inches.  To  facili- 
tate the  description  of  its  several  branches  we  divide  them  into 
— 1st,  those  which  are  presumed  to  connect  it  with  other  nerves  ; 
and  2ndly,  those  which  originate  from  it. 

It  is  then  connected  by  branches  as  follow  : — 

a.  With  each  of  the  four  upper  spinal  nerves. 

b.  With  the  hypoglossal,  with  both  ganglia  of  the  pneumogastric,  and 
with  the  glosso-pharyngeal. 

c.  Its  important  cranial  branch  runs  with  the  internal  carotid  a.  into 
the  carotid  canal  of  the  temporal  bone,  and  there  divides  into  two,  an 
outer   and  an  inner.     Now   this  outer  branch  accompanies  the  artery 
through  its  bony  canal,  ramifies  upon  it  by  the  side  of  the  body  of  the 
sphenoid,  and  so  constitutes  the  '  CAROTID  PLEXUS.'     From  this  outer 
branch  a  filament  proceeds  to  the  Gasserian  ganglion,  another  to  the  sixth 

i  2 


116  SYMPATHETIC    NERVE    IN   THE    NECK. 

cranial  nerve ;  a  third  joins  the  great  petrosal  branch  of  the  facial,  and 
forms  the  Vidian  nerve.  The  inner  branch,  running  on  with  the  artery 
to  the  cavernous  sinus,  there  forms  another  plexus,  called  from  its  posi- 
tion the  '  CAVERNOUS  PLEXUS.'  Here  the  sympathetic  is  seen  to  com- 
municate with  the  third,  the  fourth,  and  the  ophthalmic  branch  of  the 
fifth  cranial  n.  Lastly,  from  both  these  plexuses  secondary  plexuses 
proceed,  of  which  the  minute  filaments  ramify  on,  and  supply  the  coats 
of,  the  terminal  branches  of  the  internal  carotid. 

d.  With  the  several  ganglia  of  the  sympathetic  system  about  the 
head  and  neck ;  namely,  the  ophthalmic,  spheno-palatine,  otic,  and  sub- 
maxillary. 

The  branches  which  it  distributes  are — 

e.  Nerves  to  the  Heart. — One   or   more    (superior   cardiac)    descend 
behind  the  sheath  of  the  carotid  in  front  of  the  inferior  thyroid  artery  and 
recurrent  laryngeal  nerve,  and,  entering  the  chest,  join  the  superficial  and 
deep  cardiac  plexuses. 

f.  Nerves  to  the  Pharynx. — These  join  the  pharyngeal  plexus  on  the 
middle  constrictor  of  the  pharynx. 

g.  Nerves  to  the  Blood-vessels. — These  nerves,  named  on  account  of 
their  delicacy  nervi  molles,  ramify  around  the  external  carotid  artery  and 
its  branches. 

The  middle  cervical  ganglion  is  something  less  than  a  barley- 
corn in  size.  It  is  situated  behind  the  carotid  slieath,  about  the 
fifth  or  sixth  cervical  vertebra,  near  the  inferior  thyroid  artery. 
It  receives  branches  from  the  fifth  and  sixth  spinal  nerves,  and 
gives  off — 

a.  Branches  to  the  Thyroid  Body. — These   accompany   the  inferior 
thyroid  artery,  and  join  the  external  and  recurrent  laryngeal  nerves. 

b.  Branch  to  the   Heart. — This  (middle   cardiac)  nerve   usually   de- 
scends, on  the  right  side,  in  front  of  the  subclavian  artery  into  the  chest, 
where  it  lies  on  the  trachea.     It  is  joined  by  some  cardiac  filaments  from 
the  recurrent  laryngeal  nerve,  and  joins  the  deep  cardiac  plexus.     On 
the  left  side,  this  cardiac  nerve  lies  between  the  carotid  and  subclavian 
arteries. 

In  cases  where  the  middle  cervical  ganglion  is  absent,  the  pre- 
ceding nerves  are  supplied  by  the  sympathetic  cord  connecting  the 
superior  and  inferior  ganglia. 


SYMPATHETIC  NERVE  IN  THE  NECK.  117 

The  inferior  cervical  ganglion  is  of  considerable  size,  and 
is  situated,  in  the  interval  between  the  transverse  process  of 
the  seventh  cervical  vertebra  and  the  first  rib,  immediately 
behind  the  vertebral  artery.  It  receives  branches  from  the 
seventh  and  eighth  spinal  nerves,  and  others  which,  descending 
from  the  fourth  fifth  and  sixth,  through  the  foramina  in  the 
transverse  processes  of  the  vertebra,  form  a  plexus  around  the 
vertebral  artery. 

The  branches  which  it  gives  off  are — 

a.  Inferior  Cardiac  Nerve. — This  communicates  with  the  recurrent 
laryngeal  and  middle  cardiac  nerves,  and  joins  the  cardiac  plexus  beneath 
the  arch  of  the  aorta. 

b.  Nerves  to  the  Blood-vessels. — These  ramify  around  the  vertebral 
and  subclavian  arteries. 


118 


DISSECTION  OF  THE  THORAX. 

BEFORE  the  several  organs  contained  in  the  thorax  are  examined, 
the  student  should  have  some  knowledge  of  its  framework.  The 
true  ribs  with  their  cartilages  describe  a  series  of  arcs  increasing 
in  length  from  above  downwards,  and  form,  with  the  dorsal  ver- 
tebrae behind,  and  the  sternum  in  front,  a  barrel  of  a  conical  shape, 
broader  in  the  lateral  than  in  the  antero-posterior  diameter.  The 
base  is  closed  in  the  recent  state  by  a  muscle,  the  diaphragm, 
which  forms  a  muscular  partition  between  the  chest  and  the 
abdomen.  This  partition  is  arched  upwards,  so  that  it  constitutes  a 
vaulted  floor  for  the  chest,  and  by  its  capability  of  alternately  falling 
and  rising,  it  increases  and  diminishes  the  capacity  of  the  thorax. 
The  spaces  between  the  ribs  are  occupied  by  the  intercostal 
muscles.  In  each  intercostal  space  there  are  two  layers  of  these 
muscles  arranged  like  the  letter  X.  The  fibres  of  the  outer  layer 
run  obliquely  from  above  downwards  and  forwards ;  those  of  the 
inner  layer  in  the  reverse  direction. 

Such,  in  outline,  is  the  framework  of  the  thorax,  which  con- 
tains the  heart  with  its  large  vessels  and  the  lungs.  Its  walls  are 
composed  of  different  structures — bone,  cartilage,  muscles  and 
ligaments,  which  fulfil  two  important  conditions :  1st,  by  their 
solidity  and  elasticity  they  protect  the  important  organs  contained 
in  the  thorax ;  2ndly,  by  their  alternate  expansion  and  contraction 
they  act  as  mechanical  powers  of  respiration.  For  they  can  in- 
crease the  capacity  of  the  chest  in  three  directions  :  in  height,  by 
the  descent  of  the  diaphragm ;  in  width,  by  the  rotation  of  the 
ribs ;  and  in  depth,  by  the  elevation  of  the  sternum. 

BOUNDARIES  OF         The   upper   opening  of  the   osseous  thorax  is 
THE  THORAX.  bounded  posteriorly  by  the  body  of  the  first  dorsal 


DISSECTION    OF    THE    THORAX.  119 

vertebra,  laterally  by  the  first  ribs,  and  in  front  by  the  upper 
border  of  the  manubrium  sterni.  The  aperture  gives  passage  to 
the  trachea,  the  oesophagus,  the  large  vessels  of  the  head  and  neck 
and  upper  extremities,  viz.,  the  innominate,  the  left  carotid  and 
subclavian  arteries,  with  the  left  innominate  and  right  subclavian 
and  internal  jugular  veins,  the  superior  intercostal  and  internal 
mammary  arteries,  the  middle  thyroid  veins,  the  sterno-hyoid, 
sterno-thyroid  and  longus  colli  muscles,  the  pneumogastric,  the 
left  recurrent  laryngeal,  the  phrenic  and  the  sympathetic  nerves  ; 
the  cardiac  branches  of  the  sympathetic,  and  the  cardiac  branches 
of  the  pneumogastric  ;  also  to  the  first  dorsal  nerve  as  it  passes 
up  to  join  the  brachial  plexus,  the  thoracic  duct,  the  thymus  gland 
(in  early  life),  and  lastly  to  the  apices  of  the  lungs,  which,  with 
their  pleural  coverings,  rise  up  on  each  side  into  the  neck  for  about 
one  inch  and  a  half  above  the  first  rib ;  the  interspaces  between 
these  various  structures  being  occupied  by  a  dense  fibro-cellular 
tissue. 

The  base  of  the  thorax,  formed  by  the  diaphragm,  descends  in 
front  (in  the  dead  subject)  on  the  right  side  as  low  as  the  upper 
border  of  the  fifth  rib  ;  on  the  left  as  low  as  the  upper  border  of  the 
sixth  rib.* 

The  chest  of  the  female  differs  from  that  of  the  male  in  the 
following  points : — Its  general  capacity  is  less  :  the  sternum  is 
shorter ;  the  upper  opening  is  larger  in  proportion  to  the  lower ; 
the  upper  ribs  are  more  moveable,  and  therefore  permit  a  greater 

*  That  the  student  may  have  some  knowledge  of  the  diameters  of  the  chest  at  dif- 
ferent situations,  the  following  measurements  have  been  taken  from  a  well-articulated 
male  skeleton  of  the  average  height: — The  antero-posterior  diameter  at  the  upper 
opening  of  the  thorax  is  2£  inches,  at  the  articulation  of  the  manubrium  with  the 
gladiolus  it  is  4^  inches,  and  at  the  junction  of  the  gladiolus  with  the  ensiform  carti- 
lage it  has  increased  to  5|  inches.  The  transverse  diameter  of  the  upper  opening 
was  found  to  be  4f  inches;  between  the  second  ribs,  7  inches;  between  the  third, 
8£  inches;  the  diameter  increases  in  regular  proportion  as  far  as  the  ninth  rib,  where  it 
attains  a  measurement  of  I0f  inches;  below  this  it  gradually  decreases.  The  articula- 
tion of  the  manubrium  and  the  gladiolus  is  on  a  level  with  the  fourth  dorsal  vertebra  ; 
the  junction  of  the  ensiform  cartilage  with  the  gladiolus  is  on  a  level  with  the  border  of 
the  ninth  or  tenth  dorsal  vertebra;  and,  lastly,  the  upper  border  of  the  manubrium, 
corresponds  to  the  second  dorsal  vertebra. 


120  DISSECTION   OP   THE    THORAX. 

enlargement  of  the  chest  at  its  upper  part,  in  adaptation  to  the 
condition  of  the  abdomen  during  pregnancy. 

An  opening  must  be  made  into  the  chest, 
by  carefully  removing  the  upper  four-fifths 
of  the  sternum,  and  the  cartilages  of  all  the  true  ribs.*  In 
doing  this,  care  must  be  taken  not  to  wound  the  pleura,  which 
is  closely  connected  with  the  cartilages.  On  one  side  the 
internal  mammary  artery  should  be  dissected ;  on  the  other,  re- 
moved. 

In  the  dissection   of  the  chest  let  us  take  the  parts  in  the 
following  order : — 

1.  Trmngularis  sterni,  with  the  internal  mammary  artery. 

2.  Mediastina,  anterior,  middle,  and  posterior. 

3.  Right  and  left  brachio-cephalic  veins  and  superior  vena  cava. 

4.  Course  and  relations  of  the  arch  of  the  aorta. 

5.  The  three  great  branches  of  the  arch. 

6.  Course  of  the  phrenic  nerves. 

7.  Position  and  relations  of  the  heart. 

8.  Pericardium. 

9.  Pleura. 

10.  Position  and  form  of  the  lungs. 

11.  Posterior  mediastinum  and  its  contents;  namely,  the  aorta,  the  thoracic  duct, 

the  vena  azygos,  the  oesophagus,  and  pneumogastric  nerves. 

12.  Sympathetic  nerve. 

13.  Intercostal  muscles,  vessels  and  nerves. 
l'4.  Nerves  of  the  heart ;  cardiac  plexuses. 

TBIANGUIAKIS  On  the  under  surface  of  the  sternum  and  carti- 

STEKNI.  lages  of  the  ribs  is  a  thin  flat  muscle,  named  the 

triangularis  sterni.  It  arises  from  the  ensiform  cartilage,  the 
lower  part  of  the  sternum,  and  the  cartilages  of  one  or  t'wo  lower 
true  ribs,  and  is  inserted  by  digitations  into  the  cartilages  of  the 
true  ribs  from  the  sixth  to  the  second  :  its  fibres  ascend  outwards 
to  their  insertion.  This  muscle  is  evidently  a  continuation  up- 
wards of  the  anterior  portion  of  the  transversalis  abdominis.  Its 

*  Those  who  are  more  proficient  in  dissection  should  not  remove  the  whole  of  the 
sternum,  but  leave  a  quarter  of  an  inch  of  its  upper  part  with  the  first  rib  attached  to 
it.  This  portion  serves  as  a  valuable  landmark,  although  it  obstructs,  to  a  certain  ex- 
tent, the  view  of  the  subjacent  vessels. 


DISSECTION    OP    THE    THOEAX.  121 

action  is  to  depress  the  costal  cartilages,  and  thus,  on  emergency,  it 
acts  in  expiration.  Its  nerves  come  from  the  intercostal  nerves, 
its  arteries  from  the  internal  mammary. 

INTERNAL  MAM-  This  artery  is  given  off  from  the  subclavian  in 
MARY  ARTERY.  the  first  part  of  its  course.  On  entering  the  chest 
it  lies  between  the  cartilage  of  the  first  rib  and  the  pleura  and  is 
crossed  by  the  phrenic  nerve.  It  then  descends  perpendicularly, 
about  half  an  inch  from  the  sternum,  between  the  cartilages 
of  the  ribs  and  the  triangularis  sterni,  as  far  as  the  seventh 
costal  cartilage,  where  it  divides  into  two  branches,  the  inusculo- 
phrenic  and  the  superior  epigastric.  The  latter  branch  then 
enters  the  wall  of  the  abdomen  behind  the  rectus  abdominis, 
and  finally  inosculates  with  the  epigastric  (a  branch  of  the 
external  iliac).  The  branches  of  the  internal  mammary  are  as 
follows :  — 

a.  Arteria    comes   nervi  phrenici. — A   very   slender   artery,    which 
accompanies  the  phrenic  nerve  to  the  diaphragm,  and  anastomoses  with 
the  phrenic  branches  of  the  abdominal  aorta. 

b.  Mediastinal    and   thymic. — These   branches   supply   the   cellular 
tissue  of  the  anterior  mediastinum,  the  pericardium,  and  the  triangularis 
sterni.     The  thymic  are  only  visible  in  childhood,  and  disappear  with  the 
thymus  gland. 

c.  Anterior  intercostal. — Two  for  each  intercostal  space  are  distributed 
to  the  five  or  six  upper  intercostal  spaces.     They  lie  at  first  between  the 
pleura  and  the  internal  intercostal  muscle,  and  subsequently  between  the 
two  intercostals.     They  inosculate  with  the  intercostal  arteries  from  the 
aorta. 

d.  Perforating  arteries,  which   pass  through   the   same  number  of 
intercostal   spaces  as  the  preceding  branches,  and  supply  the  pectoral 
muscle  and  skin  of  the  chest.     In  the  female  they  are  of  large  size,  to 
supply  the  mammary  gland. 

e.  The  mvsculo-phrenic  branch  runs  outwards  behind  the  cartilages 
of  the  false  ribs,  and  terminates  near  the  last  intercostal  space.     It  sup- 
plies  small   branches   to   the   diaphragm,    to    the   sixth,   seventh,    and 
sometimes  the  eighth  intercostal  spaces. 

Two  venae  comites  accompany  the  artery,  and  form  a  single 


122 


DISSECTION    OF    THE    THORAX. 


trunk  at  the  upper  part  of  the  chest,  which  terminates  in  the 
brachio-cephalic  vein  of  its  own  side. 

LYMPHATIC  There   are   several   lymphatic   glands   in   the 

GLANDS.  neighbourhood  of  the  internal  mammary  artery. 

They  receive  the  lymphatics  from  the  inner  portion  of  the  mam- 
mary gland,  from  the  diaphragm,  and  the  upper  part  of  the  abdo- 
minal wall.  In  disease  of  the  inner  portion  of  the  mamma,  these 
glands  may  enlarge  without  any  enlargement  of  those  in  the 
axilla. 

If  a  transverse  section  were  made  through  the  chest  (see  fig. 
20),  you  would  observe  that  as  the  pleurae  nowhere  come  into 
actual  contact,  a  space  is  left  between  them  extending  from  the 
sternum  to  the  spine,  and  which  is  larger  in  the  middle  than  in 
front  or  behind.  This  interval  is  called  by  anatomists  the 
interpleural  space,  and  for  convenience  sake  is  subdivided  into 
an  anterior,  middle,  and  posterior  mediastinum. 

MEDIASTINA,  The  mvdiastina  are  the  spaces  which  the  two 

ANTEEIOE,  MIDDLE  pleural  sacs  leave  between  them  in  the  antero- 
AND  POSTERIOR.  posterior  plane  of  the  chest.  There  is  an  anterior, 
a  middle,  and  a  posterior  mediastinum.  To  put  these  spaces  in 
the  simplest  light,  let  us  imagine  the  heart  and  lungs  to  be  re- 
moved from  the  chest,  and  the  two  pleura!  sacs  to  be  left  in  it  by 
themselves.  The  two  sacs,  if  inflated,  would  then  appear  like  two 
FIG.  19.  bladders,  in  contact  only  in  the 

middle,  as  shown  by  the  dotted 
outlines  in  the  annexed  scheme 
(fig.  19).  The  interval  marked  a, 
behind  the  sternum,  would  repre- 
sent the  anterior  mediastinum  ; 
th  interval  6,  the  posterior  medi- 
astinum. Now  let  us  introduce 
the  heart  again,  between  the 
two  pleural  sacs  :  these  must 
give  way  to  make  room  for  it, 
so  that  the  two  sacs  are  largely 
separated  in  the  middle  line  of  the  chest;  and  the  space  thus 


DISSECTION    OF    THE    THOEAX. 


123 


occupied  by  the  heart  and  large  vessels  takes  the  name  of  the 
middle  mediastinum. 

Looking  at  the  chest  in  front,  the  anterior  mediastinum  ap- 
pears as  shown  in  the  diagram  (p.  125).  It  is  not  precisely  ver- 
tical in  its  direction,  for  it  inclines  slightly  towards  the  left,  owing 
to  the  position  of  the  heart.  Its  area  varies  :  thus  it  is  extremely 
narrow  in  the  middle  where  the  edges  of  the  lungs  nearly  meet ; 
but  it  is  wider  above  and  below,  where  the  lungs  diverge.  Poste- 
riorly it  is  limited  by  the  pericardium  covering  the  heart,  aorta 
and  its  branches,  and  the  pulmonary  artery. 

What  parts  are  contained  in  the  anterior  mediastinum  ? — The 
remains  of  the  thymus  gland,  the  origins  of  the  sterno-hyoid, 
sterno-thyroid,  and  triangularis  sterni  muscles,  the  left  brachio- 
cephalic  vein  (which  crosses  behind  the  first  bone  of  the  sternum) 
a  few  lymphatic  glands,  and  the  left  internal  mammary  artery  and. 
veins. 


I'IG.  20. 


Internal  mam- 
mary a. 


Phrenic  n. 


Internal  mam- 
mary a. 


Phrenic  n. 


(Esophagus  with 
pneumogastric  n. 
i —   Aorta. 

_  Thoracic  duct. 
_   Vena  azygos. 


DIAGRAM    OF   THE    REFLECTIONS    OF    THE   PLEtJRAL    SACS    IN    DOTTED    LINES. 

The  posterior  mediastinum  (fig.  20)  contains  the  oesophagus, 
the  two  pneumogastric  nerves,  the  aorta,  the  thoracic  duct,  the 
vena  azygos,  the  trachea,  and  some  lymphatic  glands. 


124  DISSECTION    OF   THE    THORAX. 

The  middle  mediastinum  is  the  largest  of  the  mediastina,  and 
contains  the  heart  with  its  large  vessels  and  the  phrenic  nerves. 

Before  passing  to  the  dissection  of  the  contents  of  the  thorax, 
the  student  should  carefully  trace  the  outline  of  the  free  borders 
of  the  pleurae  as  seen  in  the  front  of  the  chest.  As  the  margins  of 
the  lungs  for  all  practical  purposes  correspond  with  the  borders  of 
the  pleurae,  we  shall  confine  our  description  to  the  more  important 
of  the  two  structures,  viz.  the  lungs.  The  value  of  this  investiga- 
tion is,  that  we  are  enabled  to  trace  upon  a  living  chest  the 
outlines  of  the  lungs,  and  know  what  parts  are  naturally  resonant 
on  percussion. 

Commencing  from  above  (fig.  21,  p.  125)  we  find  that  the  apex 
of  the  lung  extends  into  the  neck,  from  an  inch  to  an  inch  and  a 
half  above  the  clavicle.  This  part  of  the  lung  ascends  behind  the 
subclavian  artery  and  the  scalenus  anticus  muscle,  and  deserves 
especial  attention,  because  it  is,  more  than  any  other,  the  seat  of 
tubercular  disease.  From  the  sternal  end  of  the  clavicles  the 
lungs  converge  towards  the  middle  line,  where  their  borders  nearly 
meet  opposite  the  junction  of  the  second  rib.  There  is  thus  little 
or  no  lung  behind  the  manubrium  sterni. 

From  the  level  of  the  second  costal  cartilage  to  the  level  of  the 
fourth,  the  inner  margins  of  each  lung  run  nearly  parallel  and 
almost  in  contact  behind  the  middle  of  the  sternum  ;  consequently 
they  overlap  the  great  vessels  at  the  root  of  the  heart. 

Below  the  level  of  the  fourth  costal  cartilage  the  margins  of 
the  lungs  diverge  from  each  other,  but  not  in  an  equal  degree. 
The  left  presents  the  notch  for  the  heart,  and  follows  nearly  the 
course  of  the  fourth  costal  cartilage ;  at  the  lower  part  of  its  curve 
it  projects  more  or  less  over  the  apex  of  the  heart  like  a  little 
tongue.  The  riyht  descends  almost  perpendicularly  behind  the 
sternum  as  low  as  the  attachment  of  the  ensiform  cartilage,  and 
then  turning  outwards  corresponds  with  the  direction  of  the  sixth 
costal  cartilage.  Hypertrophy  of  the  heart,  or  effusion  into  the  peri- 
cardium, will  not  only  raise  the  point  where  the  lungs  diverge 
above  the  ordinary  level,  but  also  increase  their  divergence ;  hence 
the  greater  dulness  on  percussion. 


POSITION    OF    THE    HEAET.  125 

The  prcecordial  region  is  the  outline  of  the* 
EEGION.  heart  traced  upon  the  front  wall  of  the  chest.     It 

is  important  for  auscultatory  purposes  that  we  should  know  how 
much  of  the  heart  is  covered  and  separated  from  the  wall  of  the 
chest  by  intervening  lung  (fig.  21).  The  following  will  give  a  fair 

FIG.  21. 


FORM  OF  THE  LUNGS,  AND  THE  EXTENT  TO  WHICH  THEY  OVERLAP  THE  HEART  AND 

ITS  VALVES. 

indication.  '  Let  the  middle  of  the  fifth  costal  cartilage  be  the 
centre  of  a  circle  two  inches  in  diameter ;  this  circle  will  define,  for 
all  practical  purposes,  that  part  of  the  praecordial  region  which  is 
naturally  less  resonant  to  percussion ;  here  the  heart  is  uncovered 
except  by  pericardium  and  loose  cellular  tissue,  and  lies  close 


126  BRACHIO-CEPHALIC    VEINS. 

behind  the  thoracic  wall.  In  the  rest  of  the  praecordial  region 
the  heart  is  covered  and  separated  from  the  chest  wall  by  inter- 
vening lung.' 

Where  should  we  put  the  stethoscope  when  we  listen  to  the 
valves  of  the  heart?  For  practical  purposes  it  is  enough  to 
remember  that  the  mouth  of  an  ordinary-sized  stethoscope  will 
cover  a  portion  of  them  all,  if  it  be  placed  a  little  to  the  left  of 
the  mesial  line  of  the  sternum  opposite  the  third  intercostal  space 
(fig.  21,  p.  125).  They  are  all  covered  by  a  thin  portion  of  lung; 
for  this  reason  we  ask  a  patient  to  stop  breathing  while  we  listen  to 
his  heart. 

Before  we  can  display  the  brachio-cephalic  veins,  the  layer  of 
the  deep  cervical  fascia  must  be  removed  which  descends  over 
them  from  the  neck  and  is  lost  upon  the  pericardium.  Their 
coats  are  intimately  connected  with  this  fascia;  and  one  of  its 
functions  appears  to  be  to  keep  the  veins  permanently  open  for 
the  free  return  of  blood  to  the  heart. 

BRACHIO-  The  right  and  left  brachio-cephalic   (innomi- 

CEPHALIC  VEINS.  nate)  veins  are  formed,  near  the  sternal  end  of 
the  clavicle,  by  the  confluence  of  the  internal  jugular  and  subclavian 
veins.  They  differ  in  their  course  and  relations,  and  must,  there- 
fore, be  described  separately. 

The  left  brachio-cephalic  vein  passes  obliquely  behind  the 
first  bone  of  the  sternum,  the  sterno-hyoid  and  thyroid  muscles, 
towards  the  right  side,  to  assist  in  forming  the  vena  cava  superior 
(fig.  22).  It  is  about  two  and  a  half  inches  in  length,  and  its  direc- 
tion inclines  a  little  downwards.  It  crosses  over  the  trachea  and  the 
origins  of  the  three  primary  branches  of  the  arch  of  the  aorta.  We 
are  reminded  of  this  fact  in  some  cases  of  aneurysm  of  these  vessels 
• — for  what  happens  ?  The  vein  becomes  compressed  between  the 
aneurysm  and  the  sternum  ;  hence  the  swelling  and  venous  con- 
gestion of  the  parts  from  which  it  returns  its  blood ;  namely,  of 
the  left  arm,  and  the  left  side  of  the  neck.  The  upper  border  of 
the  vein  is  not  far  from  the  upper  border  of  the  sternum  :  in  some 
cases  it  lies  even  higher,  and  we  have  seen  it  crossing  in  front  of 
the  trachea  fully  an  inch  above  the  sternum.  This  occasional 


VENA    CAVA    SUPERIOR. 


127 


deviation  should  be  borne  in  mind  in   the   performance  of  tra- 
cheotomy. 

The  right  brachio-cephalic  vein  descends  nearly  vertically  to 
join  the  superior  vena  cava,  opposite  the  first  right  intercostal 
space.  It  is  about  an  inch  and  a  half  in  length,  and  is  situated 
about  one  inch  from  the  mesial  line  of  the  sternum.  On  its  left 
side,  but  on  a  posterior  plane,  runs  the  arteria  innominata  ;  on  its 
right  side  is  the  pleura.  Between  the  vein  and  the  pleura  is  the 
phrenic  nerve.  The  brachio-cephalic  veins  are  not  provided  with 
valves.  The  veins  which  generally  empty  themselves  into  the 
right  and  left  brachio-cephalic  are  as  follows  : — 


The  EIGHT  B.  C.  Vein  receives : — 

The  vertebral. 

The  deep  cervical  (not  drawn). 

The  internal  mammary. 

The  middle  thyroid  (sometimes). 


The  LEFT  B.  C.  Vein  receives  :- 

The  vertebral. 

The  deep  cervical  (not  drawn). 

The  internal  mammary. 

The  middle  thyroid. 

The  superior  intercostal. 

The  pericardiac. 


FIG.  22. 


Vena  azygos 


Superior  intercostal 
Internal  mammary    .    .    


Inferior  thyroid. 

Internal  jugular. 
External  jugular. 
--—Vertebral. 

~  Supra-scapular. 
'  Posterior  scapular. 
|- Subclavian. 

Internal  mammary. 
Pericardiac. 

Superior  inter- 
costal. 


SUPERIOR   VENA    CAVA    AND    ITS    TRIBUTARIES. 


This  is  the  great  vein  through  which  the  im- 
pure blood  from  the  head,  upper  extremities,  and 
chest,  returns  into  the  right  auricle.     It  is  formed  by  the  junction 


VKNA  CAVA 
SUPKRIOR. 


128  ARCH    OF   THE    AORTA. 

of  the  right  and  left  brachio-cephalic  veins,  which  unite  at 
nearly  a  right  angle  opposite  the  first  intercostal  space  on  the 
right  border  of  the  sternum ;  that  is,  about  the  level  of  the 
highest  point  of  the  arch  of  the  aorta.  The  vena  cava  descends 
vertically,  with  a  slight  inclination  backwards,  to  the  upper 
and  anterior  part  of  the  right  auricle.  It  is  from  two  and  a 
half  to  three  inches  long.  The  lower  half  of  it  is  covered  by 
the  pericardium  ;  you  must,  therefore,  open  this  sac  to  see  how 
the  serous  layer  of  the  pericardium  is  reflected  over  the  front  and 
sides  of  the  vein.  In  respect  to  its  relations,  notice  that  the  vein 
lies  in  front  of  the  right  bronchus  and  the  right  pulmonary  ves- 
sels ;  and  that  it  is  overlapped  by  the  ascending  aorta,  which 
lies  to  its  left  side.  In  the  upper  half  of  its  course,  that  is, 
above  the  pericardium,  it  is  covered  on  its  right  side  by  the 
pleura ;  on  this  side,  in  contact  with  it,  descends  the  phrenic 
nerve. 

Before  it  is  covered  by  the  pericardium,  the  vena  cava  receives 
the  right  vena  azygos,  which  opens  into  it  after  hooking  over 
the  right  bronchus. 

The  aorta  is  the  great  trunk    from  which  all 
COURSE  AND  & 

RELATIONS  or  THE  the  arteries  of  the  body  carrying  arterial  blood  are 
ARCH  OF  THE  derived.  It  arises  from  the  upper  and  back  part 

AORTA.  of  ^e  ieft  ventricle  of  the  heart.     Its  origin  is 

situated  behind  the  pulmonary  artery  and  on  the  left  side  of  the 
sternum,  about  the  level  of  the  lower  border  of  the  third  costal 
cartilage.  It  ascends  forwards  and  to  the  right  as  high  as  the 
lower  border  of  the  first  intercostal  space  on  the  right  side ;  it  then 
curves  backwards  towards  the  left  side  of  the  body  of  the  second 
dorsal  vertebra,  and  turning  downwards  over  the  left  side  of  the 
third,  completes  the  arch  at  the  lower  border  of  the  fourth  vertebra. 
The  direction  of  the  arch,  therefore,  is  from  the  sternum  to  the 
spine,  and  rather  obliquely  from  right  to  left. 

The  arch  of  the  aorta  presents  partial  dilatations  in  certain 
situations.  One  of  these,  called  the  great  sinus  of  the  aorta, 
is  observed  on  the  right  side  of  the  arch,  about  the  junction 
of  the  ascending  with  the  transverse  portion :  it  is  little  marked 


AECH    OF    THE   AOETA.  129 

in  the  infant,  but  increases  with  age.  Three  other  dilatations  (the 
sinuses  of  Valsalva),  one  corresponding  to  each  of  the  valves  at 
.the  commencement  of  the  aorta,  will  be  examined  hereafter. 

For  convenience  of  description,  the  arch  of  the  aorta  is  divided 
into  an  ascending,  a  transverse,  and  a  descending  portion. 

Ascending  portion. — To  see  this  portion  of  the  aorta,  the 
pericardium  must  be  opened.  You  then  observe  that  this  part  of 
the  artery  is  enclosed  all  round  by  the  serous  layer  of  the  peri- 
cardium, except  where  it  is  in  contact  with  the  pulmonary  artery. 
It  is  about  two  inches  in  length,  and  ascends  with  a  slight  curve 
to  the  upper  border  of  the  second  costal  cartilage  of  the  right  side, 
where  it  lies  almost  in  contact  with  the  sternum.  Its  commence- 
ment is  covered  by  the  pulmonary  artery,  and  overlapped  by  the 
appendix  of  the  right  auricle.  On  its  right  side,  but  on  a 
posterior  plane,  descends  the  superior  vena  cava ;  on  its  left  is  the 
division  of  the  pulmonary  artery ;  behind  it,  are  part  of  the  right 
auricle,  the  right  pulmonary  artery  and  vein  and  the  right  bron- 
chus. This  part  of  the  aorta  gives  off  the  right  and  left  coronary 
arteries  for  the  supply  of  the  heart. 

Transverse  portion. — This  portion  of  the  aorta  arches  from  the 
front  to  the  back  of  the  thorax,  and  extends  from  the  upper 
border  of  the  second  right  costal  cartilage  to  the  left  side  of  the 
second  dorsal  vertebra.  In  front,  it  is  covered  by  the  left  pleura, 
and  is  crossed  by  the  left  phrenic,  the  left  pneumogastric, 
the  superficial  cardiac  nerves,  and  the  pericardiac  veins.  Near  its 
summit  runs  the  left  brachio-cephalic  vein.  Within  its  concavity 
are  the  left  bronchus,  the  bifurcation  of  the  pulmonary  artery,  the 
left  recurrent  laryngeal  nerve,  and  the  remains  of  the  ductus  arte- 
riosus.  The  artery  rests  upon  the  trachea  (a  little  above  its  bifur- 
cation), the  deep  cardiac  plexus,  the  oesophagus,  the  thoracic  duct, 
and  the  left  recurrent  laryngeal  nerve.  From  the  transverse  part 
of  the  arch  arise  the  arteria  innominata,  the  left  carotid,  and  the 
left  subclavian  arteries. 

Descending  portion. — This  part  of  the  arch  lies  upon  the  left 
side  of  the  body  of  the  third  dorsal  vertebra,  and  at  the  lower 
border  of  the  body  of  the  fourth  dorsal  it  takes  the  name  of  the 

K 


130  BRACHIO-CEPHALIC   ARTERY. 

descending  thoracic  aorta.  On  its  right  side  are  the  ossophagus 
and  thoracic  duct ;  on  its  left  is  the  pleura ;  in  front  is  the  root  of 
the  left  lung. 

What  parts  are  contained  within  the  arch  of  the  aorta  ? — The 
left  bronchus,  the  right  pulmonary  artery,  the  left  recurrent 
nerve,  the  remains  of  the  ductus  arteriosus,  and  the  superficial 
cardiac  plexus  of  nerves. 

RELATIONS  OF  These  relations  vary  according  to  the  size  of  the 

THE  AHCH  OF  THE  heart,  the  obliquity  of  the  ribs,  and  the  general 
AOETA  TO  THE  development  of  the  chest.  In  a  well-formed  adult 
STERNUM.  ^  ascen(jing  aorta  is,  at  the  most  prominent  part 

of  its  bulge,  about  half  an  inch  behind  the  first  bone  of  the 
sternum.  The  highest  part  of  the  arch  is  about  one  inch  below  the 
upper  edge  of  the  sternum.* 

From  the  upper  part  of  the  arch  arise  three  large  arteries  for 
the  head,  neck,  and  upper  limbs ;  namely,  the  brachio-cephalic  or 
innominate  artery,  the  left  carotid,  and  the  left  subclavian. 

BEACHIO-CEPHA-  This,  the  largest  of  the  three,  arises  from  the 
LIC  OK  INNOMINATE  commencement  of  the  transverse  part  of  the  arch. 
AKTEBY.  j^  ascends  obliquely  towards  the  right,  and  after  a 

course  of  about  one  inch  and  a  half  to  two  inches  divides  behind 
the  right  sterno-clavicular  joint  into  two  arteries  of  nearly  equal 
size — the  right  subclavian  and  the  right  carotid. 

The  relations  of  the  b.  c.  artery  are  as  follow.  It  lies  behind 
the  first  bone  (manubrium)  of  the  sternum  and  the  right  sterno- 
clavicular  joint.  It  ascends  obliquely  (towards  the  right)  in  front 
of  and  close  to  the  trachea.  On  its  right  side,  and  close  to  it,  is 
the  right  b.  c.  vein.  On  its  left  is  the  left  carotid  a.  In  front  of 
it  are  the  left  b.  c.  vein,  the  sterno-hyoid  and  sterno-thyroid  m. 

*  The  relations  of  the  arch  of  the  aorta  to  the  sternum  vary  even  in  adults,  more 
especially  if  there  be  any  hypertrophy  of  the  heart.  As  an  instance  among  many,  we 
may  mention  that  of  a  young  female  who  died  of  phthisis.  The  position  of  the  aortic 
valves  was  opposite  the  middle  of  the  sternum,  on  a  level  with  the  middle  of  the 
second  costal  articulation.  The  highest  part  of  the  arch  was  on  a  level  with  the  upper 
border  of  the  sternum ;  the  arteria  innominata  was  situated  entirely  in  front  of  the 
trachea  •  and  the  left  brachio-cephalic  vein  crossed  the  trachea  so  much  above  the 
sternum  that  it  would  have  been  directly  exposed  to  injury  in  tracheotomy. 


LEFT  CAEOTID  AETEEY.  131 

Parallel  with,  and  close  to,  the  artery  are  the  slender  cardiac 
nerves.* 

With  the  anatomy  of  the  parts  before  you,  you  can  under- 
stand that  an  aneurysm  of  the  innominate  artery  might  be  distin- 
guished from  an  aneurysm  of  the  aorta — 1.  By  a  pulsation  in  the 
neck  between  the  sterno-mastoid  muscles,  i.e.  in  the  fossa  above 
the  sternum ;  2.  By  occasional  dyspnoea  owing  to  pressure  on  the 
trachea;  3.  By  venous  congestion  in  the  left  arm;  4.  By  the 
aneurysmal  thrill  being  confined  to  the  right  arm.f 

LEFT  CAEOTID  This  artery  arises  from  the  arch  of  the  aorta 

ABTEBY.  close  to,  and  to  the  left  of,  the  arteria  innominata. 

It  ascends  obliquely  behind  the  first  bone  of  the  sternum,  and  the 
sterno-hyoid  and  thyroid  muscles,  to  the  neck.  In  the  first  part 
of  its  course  it  lies  upon  the  trachea,  but  it  soon  passes  to  the  left 
side  of  the  trachea,  and  then  lies  for  a  short  distance  upon  the 
ossophagus  and  thoracic  duct.  It  is  crossed  by  the  left  brachio- 
cephalic  vein ;  on  its  left  side  are  the  left  subclavian  artery  and 
pneumogastric  nerve ;  on  the  right  side  is  the  arteria  innomi- 
nata. In  the  rest  of  its  course  it  resembles  the  right  carotid 
(p.  32). 

LiFrSuBCLA-  This   is   the   third   branch    of    the   arch.      It 

TIAN  ABTEBY.  ascends  nearly  vertically  out  of  the  chest  to  the 

inner  border  of  the  first  rib,  and  then  curves  outwards  behind  the 
scalenus  anticus.  In  the  first  part  of  its  course  it  is  deeply  seated, 
and  is  covered  on  its  left  side  by  the  pleura.  Close  to  its  right 
side  are  ,the  left  carotid,  the  trachea  and  oesophagus  ;  between  the 

*  In  some  cases  the  innominate  artery  ascends  for  a  short  distance  above  the  clavicle 
before  it  divides,  lying  close  to  the  right  of  the  trachea.  We  have  already  alluded  to 
the  fact  that  it  occasionally  gives  off  a  middle  thyroid  artery  (p.  37),  which  ascends  in 
fronfc  of  the  trachea  to  the  thyroid  body,  and  is  therefore  directly  in  the  way  in 
tracheotomy. 

f  If  the  innominate  artery  be  ligatured,  the  circulation  would  be  maintained  by  the 
following  collateral  branches: — 1.  Between  the  branches  of  the  two  external  carotids, 
which  anastomose  across  the  middle  line.  2.  Between  the  aortic  intercostal  and  the 
superior  intercostal.  3.  Between  the  aortic  intercostals  and  the  internal  mammarj, 
long  thoracic,  alar  thoracic,  and  subscapular  arteries.  4.  Between  the  internal 
mammary  and  deep  epigastric.  5.  Between  the  inferior  thyroid  arteries.  6.  Between 
the  two  vertebrals.  7-  Between  the  two  internal  carotid  arteries. 

x  2 


132  PHRENIC    NERVES. 

artery  and  the  oesophagus  is  the  thoracic  duct.  Like  the  other 
primary  branches  of  the  arch,  it  is  crossed  by  the  left  brachio- 
cephalic  vein.  It  is  covered  in  front  by  the  left  lung,  and  it  rests 
upon  the  longus  colli.  Anterior  to  the  artery  also  are  the  pneumo- 
gastric,  the  phrenic,  and  the  cardiac  nerves.  The  upper  part  of  its 
course,  where  the  vessel  passes  in  front  of  the  apex  of  the  lung, 
has  been  described  with  the  anatomy  of  the  neck  (p.  62). 

COUBSE  OF  THE  The  phrenic  nerve  comes  from  the  third,  fourth 
PHRENIC  NEBVES  and  fifth  cervical  nerves.  It  descends  over  the 
THROUGH  THK  scalenus  anticus,  and  enters  the  chest  between 

the  subclavian  vein  and  artery.  It  then  crosses 
over  the  internal  mammary  artery  and  runs  in  front  of  the  root  of 
the  lung  between  the  pleura  and  the  pericardium  to  the  diaphragm 
(fig.  23),  to  the  under  surface  of  which  it  is  distributed.* 

The  phrenic  nerve  is  joined  on  the  scalenus  anticus  by  an 
offset  from  the  fifth  cervical  branch  of  the  brachial  plexus ;  by 
another  filament  from  the  sympathetic  nerve  ;  and  very  frequently 
by  a  small  loop  from  the  nerve  to  the  subclavius  muscle ;  occa- 
sionally also  by  a  branch  from  the  descendens  noni. 

In  what  respects  do  the  phrenic  nerves  differ  from  each  other  in 
their  course  ? — The  right  phrenic  runs  along  the  outer  side  of  the 
brachio-cephalic  vein  and  superior  vena  cava ;  the  left  crosses  in 
front  of  the  transverse  part  of  the  arch  of  the  aorta ;  besides  which, 
the  left  is  rather  longer  than  the  right,  since  it  curves  over  the 
apex  of  the  heart. 

Before  the  phrenic  nerve  divides  into  branches  to  supply  the 
diaphragm,  it  sends  off  minute  filaments  to  the  pleura  and  the 
pericardium. 

Having  studied  these  anatomical  details,  consider  for  a  moment 
what  symptoms  are  likely  to  be  produced  by  an  aneurysm  of  the 
arch  of  the  aorta,  or  any  of  the  primary  branches.  A  glance  at  the 
important  parts  in  the  neighbourhood  helps  to  answer  the  question. 
The  effects  will  vary  according  to  the  part  of  the  artery  which 

*  In  the  Museum  of  the  College  of  Surgeons  there  is  a  dissection  showing  that  the 
right  phrenic  nerve  enters  the  diaphragm  close  to  the  right  side  of  the  vena  cava 
inferior,  while  the  left  phrenic  enters  the  left  muscle  of  the  diaphragm. 


PHRENIC    NERVES. 


133 


is  the  seat  of  the  aneurysm,  and  according  to  the  size,  the  form, 
and  the  position  of  the  tumour.  One  can  understand  that  com- 
pression of  the  vena  cava  superior,  or  either  of  the  brachio-cephalic 


FIG.  23. 


3rd  cervical  n. 

4th  cervical  n. 
Pncumogas- 
tric  n.     .    . 


5th  cervical  n.       — 


Brachial  plexus 


Phrenic  n.  .    . 

Line  of  reflec- 
tion of  peri- 
cardium. 


Cervicalis  ascendens  a. 
Scalenus  anticus. 
Inferior  thyroid  a. 

Snperficinlis  colli  a. 
Phrenic  n. 
Posterior  scapular  a. 

Supra-scapular  a. 
Subclavian  a. 

Superior  intercostal  a. 
Internal  mammary  a. 
Pneumogastric  n. 
Phrenic  n. 

Appendix  of  left  auricle. 


veins,  would  occasion  congestion  and  cedema  of  the  parts  from 
which  they  return  the  blood ;  that  compression  of  the  trachea 
or  one  of  the  bronchi  might  occasion  dyspnoea,  and  thus  simulate 


134  POSITION    OF    THE    HEAET. 

disease  of  the  larynx ;  *  that  compression  of  the  cesophagus  would 
give  rise  to  symptoms  of  obstruction.  Nor  must  we  forget  the 
immediate  vicinity  of  the  thoracic  duct  and  the  recurrent  nerve,f 
and  the  effects  which  would  be  produced  by  their  compression. 
Can  one,  then,  be  surprised  that  a  disease  which  may  give  rise  to 
so  many  different  symptoms  should  be  a  fertile  source  of  fallacy  in 
diagnosis  ? 

Thus  you  can  understand  how  aneurysms  of  the  aorta  may 
prove  fatal,  by  bursting  into  the  contiguous  tubes  or  cavities ;  for 
instance,  into  the  trachea,  the  oesophagus,  the  pleura,  or  the 
pericardium.  You  will  see,  too,  why  an  aneurysm  of  the  first  part 
of  the  arch  is  so  much  more  dangerous  than  elsewhere.  The 
reason  is,  that  in  this  part  of  its  course  the  aorta  is  covered  only 
by  a  thin  layer  of  serous  membrane.  If  an  aneurysm  take  place 
here,  the  coats  of  the  vessel  soon  become  distended,  give  way,  and 
allow  the  blood  to  escape  into  the  pericardium  ;  an  occurrence 
which  is  speedily  fatal,  because,  the  pericardium  being  filled  with 
blood,  the  heart  is  prevented  from  acting. 

POSITION  AND  The  heart  is  situated  obliquely   in  the  chest, 

FORM  or  THE  between   the  lungs.     Its  base,  i.e.  the  part    by 

HEART.  which   it  is  attached,  and  from  which  its  great 

vessels  proceed,  is  directed  upwards  towards  the  right  shoulder ;  its 
apex  points  downwards  and  to  the  left,  between  the  fifth  and  sixth 
costal  cartilages.  It  is  supported,  towards  the  abdomen,  by  the 
tendinous  centre  of  the  diaphragm.  It  is  maintained  in  its  posi- 
tion by  a  membranous  bag  termed  the  pericardium,  which  is  lined 
by  a  serous  membrane  to  facilitate  its  movements.  The  pericar- 
dium must  first  claim  our  attention. 

The  pericardium  is  the  membranous  bag  which 

encloses  the  heart  and  the  large  vessels  at  its  base. 

It  is  broadest  below,  where  it  is  attached  to  the  tendinous  centre 

of  the  diaphragm,  and  to  the  muscular  part  in  connection  with 

*  In  the  Museum  of  Guy's  Hospital  there  is  a  preparation,  No.  1487,  in  which 
laryngotomy  was  performed  under  the  circumstances  described  in  the  text. 

f  See  'Med.  Gaz.,'  Dec.  22nd,  1843.  A  case  in  which  loss  of  voice  was  produced 
by  the  pressure  of  an  aneurysmal  tumour  upon  the  left  recurrent  nerve. 


POSITION    OP   THE    HEART.  135 

the  tendon ;  above,  it  is  prolonged  over  the  great  vessels  of  the 
heart,  and  is  connected  with  the  deep  cervical  fascia.   On  each  side, 


FIG.  24. 


EELATIVB    POSITION   OF    THE    HEART    AND    ITS   VALVES    WITH    REGARD    TO 
THE    WALLS    OF   THE   CHEST. 

The  valves  are  denoted  by  curved  lines.  The  aortic  valves  are  opposite  the  third  in- 
tercostal space  on  the  left  side,  close  to  the  sternum.  The  pulmonary  valves  are 
just  above  the  aortic,  opposite  the  junction  of  the  third  rib  with  the  sternum.  The 
mitral  wtlws  are  opposite  the  third  intercostal  space,  about  one  inch  to  the  left  of 
the  sternum.  The  tricuspid  valves  lie  behind  the  middle  of  the  sternum,  about  the 
level  of  the  fourth  rib.  Aortic  murmurs,  as  shown  by  the  arrow,  are  propagated 
up  the  aorta :  mitral  murmurs,  as  shown  by  the  arrow,  are  propagated  towards 
the  apex  of  the  heart. 

it  is  in  contact  with  the  pleura  ;  the  phrenic  nerve  running  down 
between  them.    In  front  of  it,  is  the  anterior  mediastinum  ;  behind 


136  PERICARDIUM. 

it,  is  the  posterior.  Of  the  objects  in  the  posterior  mediastinum, 
that  which  is  nearest  to  the  pericardium  is  the  oesophagus.  It 
should  be  remembered  that  the  oesophagus  is  in  close  contact  with 
the  back  of  the  pericardium  and  left  auricle  for  nearly  two  inches  ; 
this  fact  accounts  for  what  is  sometimes  observed  in  cases  of 
pericarditis  where  there  is  much  effusion ;  namely,  pain  and 
difficulty  in  swallowing. 

The  pericardium  is  a  fibro-serous  membrane.  Its  fibrous  layer, 
which  constitutes  its  chief  strength,  is  external.  This  layer  is 
attached,  below,  to  the  central  tendon  and  the  adjoining  muscular 
part  of  the  diaphragm.  Above,  it  forms  eight  sheaths  for  the  great 
vessels  at  the  base  of  the  heart ;  namely,  one  for  the  vena  cava 
superior,  four  for  the  pulmonary  veins,  two  for  the  pulmonary 
arteries,  and  one  for  the  aorta.  The  serous  layer  forms  a  shut  sac. 
It  lines  the  fibrous  layer  to  which  it  is  intimately  attached,  and  is 
reflected  over  the  great  vessels  and  the  heart.  To  see  where  the 
serous  layer  is  reflected  over  the  vessels,  distend  the  pericardium 
with  air.  Thus  you  will  find  that  this  layer  is  reflected  over  the 
aorta  as  high  as  the  origin  of  the  arteria  innominata.  It  is 
reflected  over  the  front  of  the  vena  cava  superior. 

The  serous  layer  of  the  pericardium  covers  the  large  vessels  to 
an  extent  greater  than  is  generally  imagined ;  though  the  extent  is 
not  precisely  similar  in  all  bodies.  The  aorta  and  pulmonary  artery 
are  enclosed  in  a  complete  sheath,  two  inches  in  length,  so  that  these 
vessels  are  covered  all  round  by  the  serous  layer,  except  where  they 
are  in  contact.  Indeed  you  can  pass  your  finger  behind  them 
both,  through  a  foramen  bounded,  in  front,  by  the  two  great  vessels 
themselves,  behind,  by  the  upper  part  of  the  auricles,  and  above, 
by  the  right  pulmonary  artery.  Again,  the  back  of  the  aorta, 
where  it  lies  on  the  auricles,  is  covered  by  the  serous  pericardium. 
The  superior  cava  is  covered  all  round,  except  behind,  where  it 
crosses  the  right  pulmonary  artery.  The  inferior  cava  within  the 
pericardium  is  partly  covered  in  front.  The  left  pulmonary 
veins  are  covered  nearly  all  round ;  the  right  less  so.  Behind  the 
auricles,  chiefly  the  left,  the  serous  layer  extends  upwards  in  the 
form  of  a  pouch,  rising  above  their  upper  border,  so  as  to  be  loosely 


PR^ECORDIAL   REGION.  137 

connected  to  the  left  bronchus.  The  object  of  these  serous  reflec- 
tions is  to  facilitate  the  free  action  of  the  heart  and  the  great 
vessels  at  its  base. 

In  the  healthy  state,  the  capacity  of  the  pericardium  nearly 
corresponds  to  the  size  of  the  heart  when  distended  to  its  utmost. 
The  healthy  pericardium,  with  the  heart  in  situ,  may  be  made  to 
hold,  in  the  adult,  about  ten  ounces  of  fluid.  The  pericardium  is 
not  extensile.  When  an  aneurysm  bursts  into  it,  death  is  caused, 
not  by  loss  of  blood,  but  by  compression  of  the  heart  in  consequence 
of  the  inextensibility  of  the  pericardium. 

The  pericardium  derives  its  blood  from  the  internal  mammary, 
bronchial,  and  oesophageal  arteries. 

On  separating  the  left  pulmonary  artery  and  pulmonary  vein, 
you  will  notice  a  fold  of  serous  membrane  about  three-quarters  of 
an  inch  long  and  about  one  inch  in  depth  :  this  is  the  vestigial 
fold  of  the  pericardium,  described  by  Marshall.*  It  passes 
from  the  side  of  the  left  auricle  to  the  left  superior  intercostal 
vein.  It  is  a  vestige  of  the  left  v.  c.  superior  which  exists  in 
foetal  life. 

Open  the  pericardium,  and  observe  that  the  heart  is  conical 
in  form,  and  convex  everywhere  except  upon  its  lower  surface, 
which  is  flat,  and  rests  upon  the  tendinous  centre  of  the  diaphragm. 
When  the  pericardium  is  thus  laid  open,  the  following  objects  are 
exposed :  viz.  1.  Part  of  the  right  ventricle  ;  2.  Part  of  the  left 
ventricle  ;  3.  Part  of  the  right  auricle  with  its  appendix  over- 
lapping the  root  of  the  aorta ;  4.  The  appendix  of  the  left  auricle 
overlapping  the  root  of  the  pulmonary  artery ;  5.  The  aorta ;  6. 
The  pulmonary  artery ;  7.  The  vena  cava  superior ;  8.  The  right 
and  left  coronary  arteries. 

POSITIOK  OF  The  heart  then,  placed  behind  the  lower  half 

THB  HEART —  of  the  sternum,  occupies  more  of  the  left  than  the 

CONTINUED.  right  half  of  the  chest,  and  rests  upon  the  ten- 

dinous  centre   of  the   diaphragm,  which   is   a  little   below  the 
lowest  part  of  the  fifth  rib.      At  each  contraction  the  apex  of 
the  heart  may  be  felt  beating  between  the  cartilages  of  the  fifth 
*  'Philosoph.  Transactions,'  1850. 


138  PR^ECORDIAL    REGION. 

and  sixth  ribs,  about  two  inches  below  the  nipple  and  an  inch  to 
its  sternal  side.  Speaking  broadly,  the  base  corresponds  with  a 
line  drawn  across  the  sternum  along  the  upper  borders  of  the  third 
costal  cartilages.  The  right  border  of  the  heart  is  formed  almost 
entirely  by  the  free  margin  of  the  right  auricle,  and,  when  dis- 
tended, bulges  nearly  an  inch  to  the  right  of  the  sternum.  The 
left  border  of  the  heart  is  formed  by  the  round  border  of  the  left 
ventricle,  and  reaches  from  a  point,  commencing  at  the  second 
left  intercostal  space,  to  a  point  placed  two  inches  below  the 
nipple  and  an  inch  to  its  sternal  side.  The  horizontal  border  is 
formed  by  the  sharp  margin  of  the  right  ventricle,  and  extends 
from  the  sternal  attachment  of  the  fifth  right  costal  cartilage,  to 
meet  the  lowest  point  of  the  left  margin. 

The  normal  position  which  the  cardiac  valves  hold  to  the 
thoracic  walls  is  difficult  to  define  with  precision,  and  this  probably 
accounts  for  the  discrepancies  noticed  in  anatomical  works  on 
this  subject.  The  following  relations  are  the  results  of  care- 
fully made  observations  in  the  *  post-mortem '  room :  The  right 
auricula-ventricular  valves  are  situated  behind  the  sternum  about 
the  level  of  the  fourth  costal  cartilage :  the  left  auriculo-ventri- 
cular  valves  are  opposite  the  third  intercostal  space,  about  one 
inch  to  the  left  of  the  sternum ;  the  cusps  of  these  valves  extend 
as  low  as  the  fifth  costal  cartilage.  The  pulmonary  valves  lie 
immediately  behind  the  junction  of  the  third  left  costal  cartilage 
with  the  sternum  ;  the  aortic  valves  are  behind  the  upper 
border  of  the  third  intercostal  space  just  at  the  left  side  of  the 
sternum. 

The  position  of  the  heart  varies  a  little  with  the  position  of  the 
body.  Of  this  anyone  may  convince  himself  by  leaning  alter- 
nately forwards  and  backwards,  by  lying  on  this  side  and  on  that, 
placing  at  the  same  time  his  hand  upon  the  prsecordial  region. 
He  will  find  that  he  can,  in  a  slight  degree,  alter  the  place  and  the 
extent  of  the  impulse  of  the  heart.  Inspiration  and  expiration 
also  alter  the  position  of  the  heart.  In  inspiration  the  heart 
descends  with  the  tendinous  centre  of  the  diaphragm  about  half 
an  inch. 


PLEURA.  139 

As  the  lungs  are  continually  gliding  to  and  fro, 

PLEURA 

within  the  chest,  they  are  provided  with  a  serous 
membrane  to  facilitate  their  motion.  This  membrane  is  termed 
the  pleura.  There  is  one  for  each  lung.  Each  pleura  forms  a 
completely  closed  sac,  and,  like  all  other  serous  sacs,  has  a  parietal 
and  a  visceral  layer ;  that  is,  one  part  of  the  sac  lines  the  contain- 
ing cavity,  the  other  is  reflected  over  the  contained  organ.  Its 
several  parts  are  named  after  the  surface  to  which  they  adhere  : 
that  which  lines  the  ribs  is  called  pleura  costalis;  that  which 
covers  the  lung,  pleura  pulmonalis.  Unlike  the  peritoneum,  the 
pleura  forms  no  folds  except  a  small  one  called  ligamentum 
latum  pulmonis,  which  extends  from  the  root  of  the  lung  to  the 
diaphragm. 

The  pleural  sac  (fig.  20,  p.  123)  lines  the  ribs  and  part  of  the 
sternum  ;  from  the  sternum  it  is  reflected  backwards  over  the  peri- 
cardium ;  from  thence  it  passes  over  the  front  of  the  root  of  the 
lung,  and  so  on  over  the  entire  lung  to  the  back  part  of  its  root, 
whence  it  is  reflected  over  the  sides  of  the  vertebrae,  and  thus 
reaches  the  ribs  and  the  diaphragm. 

The  thickness  of  the  pleura  differs ;  on  the  lung  it  is  thin, 
semi-transparent,  and  firmly  adherent ;  on  the  ribs  and  diaphragm 
it  is  thick,  and  may  be  easily  separated  from  its  osseous  and 
muscular  connections. 

The  spaces  called  anterior  and  posterior  mediastina,  formed 
by  the  separation  of  the  pleura?,  have  been  already  described, 
p.  123. 

In  health  the  internal  surface  of  the  pleura  is  smooth,  polished, 
and  lubricated  by  moisture  sufficient  to  facilitate  the  sliding  of 
the  lung.*  When  this  surface  is  thickened  and  roughened  by 
inflammation,  the  moving  lung  produces  a  friction  sound.  When 
the  pleural  sac  is  distended  by  serum,  it  constitutes  hydro-thorax  ; 
when  by  pus,  empyema ;  when  by  air,  pneumo-thorax ;  when  by 
blood,  haemo-thorax. 

*  The  pleura  costalis  is  covered  with  flattened  epithelial  cells ;  the  pleura  pul- 
monalis with  polyhedral  granular  cells.  (Klein.) 


140  THE    LUNGS. 

Introduce  your  hand  into  the  pleural  sac,  and  ascertain  that  the 
reflection  of  the  pleura  on  to  the  diaphragm  corresponds  with  an 
imaginary  line  commencing  at  the  lower  part  of  the  sternum,  and 
sloping  along  the  cartilages  of  the  successive  ribs  down  to  the 
lower  border  of  the  last  rib.  Supposing  a  ball  to  lodge  in  the 
pleural  sac,  it  might  fall  upon  the  dome  of  the  diaphragm,  and 
roll  down  to  the  lowest  part  of  the  pleural  cavity.  The  place, 
therefore,  to  extract  it,  would  be  in  the  back,  at  the  eleventh 
intercostal  space.  This  operation  has  been  done  during  life  with 
success. 

POSITION  AND  The  lungs  are  situated  in  the  chest,  one  on  each 

FOKM  OF  THE  side  of  the  heart.      Each  fits  accurately  into  the 

LUNGS,  cavity  which  contains  it.     Each,  therefore,  is  co- 

nical in  form  ;  the  base  rests  on  the  diaphragm ;  the  apex  projects 
into  the  root  of  the  neck  a  little  more  than  an  inch  above  the 
sternal  end  of  the  clavicle.  Its  outer  surface  is  adapted  to  the 
ribs  ;  its  inner  surface  is  excavated  to  make  room  for  the  heart. 
The  best  way  to  see  the  shape  of  the  lungs  is  to  inject  them  through 
the  trachea  with  wax,  which  is  tantamount  to  taking  a  cast  of  each 
thoracic  cavity.  In  such  a  preparation,  besides  the  general  con- 
vexities and  concavities  alluded  to,  you  would  find  in  the  right  lung 
a  little  indentation  for  the  right  brachio- cephalic  vein,  in  the  left 
an  indentation  for  the  arch  of  the  aorta  and  the  left  subclavian 
artery. 

Each  lung  is  divided  into  an  upper  and  a  lower  lobe  by  a  deep 
fissure,  which  commences,  behind,  about  three  inches  from  the 
apex,  and  proceeds  obliquely  downwards  and  forwards  to  the  junc- 
tion of  the  6th  rib  with  its  cartilage  (fig.  21).  Speaking  broadly, 
nearly  the  whole  of  the  anterior  portion  of  the  lung  is  formed  by 
the  upper  lobe ;  nearly  the  whole  of  the  posterior  portion  by  the 
lower  lobe.  It  should  be  noticed,  however,  that  the  upper  lobe 
of  the  right  lung  is  divided  by  a  second  fissure  which  marks  off, 
from  its  lower  part,  a  triangular  portion  called  its  middle  lobe. 

The  dimensions  of  the  right  lung  are  greater  than  those  of  the 
left  in  all  directions  except  the  vertical ;  the  reason  of  this  excep- 
tion is  the  greater  elevation  of  the  diaphragm  on  the  right  side 


CONTENTS    OF    POSTERIOE    MEDIASTINUM.  141 

by  the  liver.  On  an  average,  the  right  lung  weighs  24  ounces  ; 
the  left  21  ounces. 

POSTERIOR  The  posterior  mediastinum  (p.  123)  is  formed 

MEDIASTINUM  AND  by  the  reflection  of  the  pleural  sac  on  each  side, 
ITS  CONTENTS.  from  the  root  of  the  limg  to  the  sideg  of  the  bodieg 

of  the  dorsal  vertebrse.  It  is  bounded  in  front  by  the  pericardium. 
To  obtain  a  view  of  it,  draw  out  the  right  lung,  and  fasten  it  to 
the  left  side.  This  mediastinum  contains  the  descending  thoracic 
aorta ;  in  front  of  the  aorta,  the  cesopha,gus,  with  the  pneumogas- 
tric  nerves  ;  on  the  right  of  the  aorta  is  the  vena  azygos  ;  between 
this  vein  and  the  aorta  is  the  thoracic  duct ;  superiorly  is  the 
trachea  ;  inferiorly  are  the  splanchnic  nerves  and  some  lymphatic 
glands.  To  expose  these  last,  we  must  remove  the  pleura,  and  a 
layer  of  dense  fascia  which  lines  the  chest  outside  it. 

DESCENDING  We  have  already  traced  the  arch  of  the  aorta  to 

THORACIC  AORTA,  the  lower  border  of  the  body  of  the  fourth  dorsal 
vertebra  (p.  129).  From  this  point,  the  aorta  descends  on  the  left 
side  of  the  spine,  gradually  approaching  towards  the  middle  line. 
The  artery,  moreover,  following  the  dorsal  spinal  curve  is  not 
vertical,  but  concave  forwards.  Opposite  the  last  dorsal  vertebra 
it  passes  between  the  crura  of  the  diaphragm  and  enters  the 
abdomen.  Its  left  side  is  covered  by  pleura ;  on  its  right  run 
the  vena  azygos,  the  oesophagus,  and  thoracic  duct ;  in  front 
of  it  are,  the  root  of  the  left  lung,  and  the  pericardium. 
Lower  down  the  oasophagus  is  in  front  of  the  artery,  and  subse- 
quently lies  a  little  to  its  left  side.  Its  branches  will  be  described 
presently. 

VENA  AZYGOS  This  vein  commences  in  the  abdomen  by  small 

MAJOR  AND  branches  from  one  of  the  lumbar  veins  of  the  right 

MlNOB-  side,  and  generally  communicates  with  the  renal, 

or  the  vena  cava  itself.  This,  indeed,  is  the  main  point  about  the 
origin  of  the  vena  azygos,  that  it  communicates  directly  or 
indirectly  with  the  vena  cava  inferior.  It  enters  the  chest  through 
the  aortic  opening  of  the  diaphragm,  and  ascends  on  the  right 
side  of  the  aorta  through  the  posterior  mediastinum,  in  front 
of  the  bodies  of  the  lower  dorsal  vertebra,  and  over  the  right 


142 


THOEACIC    DUCT. 


intercostal  arteries.  When  the  vein  reaches  the  level  of  the  third 
dorsal  vertebra,  it  arches  over  the  right  bronchus,  and  terminates 
in  the  superior  vena  cava,  just  before  this  vessel  is  covered  by 
pericardium.  In  its  course  it  receives  all  the  right  intercostal 
veins,  the  spinal  veins,  the  oesophageal  and  commonly  the  right 
FIG.  25.  bronchial  vein.  Opposite  the 

sixth  or  seventh  dorsal  vertebra  it 
is  joined  by  the  left  vena  azygos. 
The  left  vena  azygos,  vena 
azygos  minor,  runs  up  the  left 
side  of  the  spine.  This  vein 
commences  in  the  abdomen  from 
one  of  the  lumbar  veins  of 
the  left  side,  or  from  the  left 
renal.  It  then  ascends  on  the 
left  side  of  the  aorta,  through 
the  aortic  opening  in  the  dia- 
phragm. On  a  level  wth  the 
sixth  or  seventh  dorsal  vertebra, 
it  passes  beneath  the  aorta  and 
thoracic  duct  to  join  the  azygos 
major.  Before^  passing  beneath 
the  aorta  it  usually  communicates 
with  the  left  superior  intercostal 
vein.  It  generally  receives  six 
or  seven  of  the  lower  intercostal 
veins  of  the  left  side.  These 
azygos  veins  are  provided  with 
imperfect  valves,  and  are  supple- 
mental to  the  inferior  vena  cava. 

THOKACIC  DUCT  The      thoracic 

AND  EECEPTA-         duct   (figure  25) 
CULUM  CHYLI,  js   a    canal   about 

eighteen    inches    long,    through 
which  the  contents  of  the  lacteal 
vessels  from  the  intestines  and  the  lymphatics  from  the  lower  limbs 


DIAGRAM    TO    SHOW   THE    COURSE    OF    THE 
VENA   AZYGOS  AND  THE  THORACIC  DUCT. 


(ESOPHAGUS.  143 

are  conveyed  into  the  blood.  These  vessels  converge  to  a  general 
receptacle,  termed  receptaculum  chyli,  situated  in  front  of  the 
body  of  the  second  lumbar  vertebra.  From  this  dilatation,  the 
duct  ascends  at  first  behind  the  aorta.  Then  getting  to  its  right 
side,  it  passes  through  the  aortic  opening  of  the  diaphragm  into 
the  chest,  and  runs  up  the  posterior  mediastinum,  still  along  the 
right  side  of  the  aorta,  between  this  vessel  and  the  vena  azygos 
major.  Near  the  third  dorsal  vertebra,  it  passes  behind  the  arch 
of  the  aorta  and  the  oesophagus,  and  ascends  on  the  left  side  of 
this  tube,  between  it  and  the  left  subclavian  artery,  as  high  as  the 
seventh  cervical  vertebra,  where  it  describes  a  curve  with  the  con- 
vexity upwards,  and  opens  in  front  of  the  scalenus  anticus  into  the 
back  part  of  the  confluence  of  the  left  internal  jugular  and  sub- 
clavian veins.  The  orifice  of  the  duct  is  guarded  by  two  valves 
which  permit  fluid  to  pass  from  the  duct  into  the  vein,  but  not 
vice  versa.  Valves,  disposed  like  those  in  the  venous  system,  are 
placed  at  short  intervals  along  the  duct,  so  that  its  contents  can 
only  pass  upwards.*  The  diameter  of  the  duct  varies  in  different 
parts  of  its  course  ;  at  its  commencement  it  is  about  three  lines  in 
diameter,  at  the  sixth  dorsal  it  is  about  two  lines,  and  it  enlarges 
again  towards  the  termination.  It  receives  the  lymphatics  from 
the  lower  extremities,  and  from  all  the  abdominal  viscera  (except 
the  convex  surface  of  the  liver  and  the  abdominal  walls),  above 
these  it  receives  the  lymphatics  from  the  left  side  of  the  thorax, 
the  left  lung,  the  heart,  the  left  upper  extremity,  and  the  left  side 
of  the  head  and  neck. 

The  oesophagus  is  that  part  of  the  alimentary 

(ESOPHAGUS.  \  F  J 

canal  which  conveys  the  food  from  the  pharynx 

to  the  stomach.     It  commences  at  the  lower  border  of  the  fifth 
cervical  vertebra,  at  the  back  of  the  cricoid  cartilage  ;  runs  down 


*  It  is  right  to  state  that  the  thoracic  duct  varies  in  size  in  different  individuals. 
It  may  divide  in  its  course  into  two  branches,  which  subsequently  reunite ;  instead 
of  one,  there  may  be  several  terminal  orifices.  Instances  have  been  observed  in  which 
the  duct  has  terminated  on  the  right  instead  of  the  left  side  (Fleischmann;  'Leichen- 
offnungen,'  1815;  also  Morrison,  'Journal  of  Anat.,'  vol.  vi.  p.  427).  It  has  been  seen 
to  terminate  in  the  vena  azygos  (Miiller's  'Archiv,'  1834). 


144  (ESOPHAGUS. 

first  to  the  right  side  of  the  transverse  portion  of  the  arch  of  the 
aorta,  then  through  the  posterior  mediastinum  in  front  of  the 
descending  aorta,  and  passes  through  the  oesophageal  opening  in 
the  diaphragm  to  the  stomach.  It  is  from  nine  to  ten  inches 
long.  Its  course  is  not  exactly  straight ;  in  the  neck,  it  lies 
behind  and  a  little  to  the  left  of  the  trachea ;  in  the  chest,  i.e. 
about  the  fourth  dorsal  vertebra,  it  inclines  towards  the  right  side, 
to  make  way  for  the  aorta ;  but  it  again  inclines  to  the  left  before 
it  passes  through  the  diaphragm.  It  has  moreover  an  antero- 
posterior  curve  corresponding  to  the  curve  of  the  spine. 

The  oesophagus,  in  the  first  part  of  its  course,  rests  upon  the 
longus  colli  muscle,  then  upon  the  thoracic  duct  and  the  third, 
fourth,  and  fifth  intercostal  vessels  of  the  right  side,  and,  lastly,  it 
lies  in  front,  and  slightly  to  the  left  side,  of  the  aorta.  In  front 
of  it  is  the  trachea  and  the  left  bronchus.  Before  it  passes  through 
the  diaphragm  it  lies  in  close  contact  with  the  pericardium  (behind 
the  left  auricle)  for  nearly  two  inches ;  this  accounts  for  the  pain 
which  is  sometimes  experienced  in  cases  of  pericarditis,  during 
the  passage  of  food. 

In  the  neck,  the  oesophagus  is  in  connection,  laterally,  with  the 
thyroid  body,  the  common  carotid  and  inferior  thyroid  arteries,  and 
the  recurrent  laryngeal  nerves  ;  to  the  left  of  it  is  the  thoracic  duct. 
In  the  thorax  the  aorta  is  to  the  left,  and  the  vena  azygos  major 
to  the  right,  of  the  tube.  As  it  passes  down  in  the  inter-pleural 
space,  it  is  in  connection  with  both  pleurae.  The  oesophagus  is 
surrounded  by  a  plexus  of  nerves,  formed  by  the  pneumogastric 
nerves,  the  left  being  in  front,  the  right  behind  it. 

The  oesophagus  is  supplied  with  blood  by  the  inferior  thyroid, 
the  oesophageal  branches  of  the  aorta,  the  coronaria  ventriculi,  and 
the  left  phrenic  artery.  It  is  supplied  with  nerves  by  the  pneumo- 
gastric and  the  sympathetic,  which  ramify  between  the  two 
muscular  layers.  The  oesophagus  is  composed  of  three  coats,  an 
external  or  muscular,  a  middle  or  areolar,  and  an  internal  or 
mucous.  The  muscular  coat  consists  of  an  outer  longitudinal  and 
an  inner  circular  layer  of  fibres.  The  longitudinal  layer  is  parti- 
cularly strong,  and  arranged  in  the  upper  part  mainly  in  three 


PNEUMOGASTEIC    IN   THE    CHEST.  145 

bundles,  an  anterior  and  two  lateral ;  these,  lower  down,  spread 
out  and  form  a  continuous  layer  round  the  oesophagus  and  support 
the  circular  fibres.  Under  the  microscope  the  muscular  fibres 
composing  the  upper  part  are  seen  to  consist  entirely  of  the  striped 
variety ;  at  the  lower  part,  almost  exclusively  of  the  non-striped 
variety.  The  middle  coat  is  composed  of  areolar  tissue,  and  con- 
nects very  loosely  the  muscular  and  mucous  coats.  The  mucous 
membrane  is  of  a  pale  colour  and  considerable  thickness,  and  in 
the  contracted  state  of  the  oesophagus  is  arranged  in  longitudinal 
folds  within  the  tube  which  lies  flattened  in  front  of  the  spine. 
On  the  surface  of  the  mucous  membrane  there  are  numerous 
minute  papillae  placed  obliquely.  It  is  lined  by  a  very  thick  layer 
of  scaly  epithelium.  In  the  submucous  tissue  are  many  small 
compound  racemose  glands — oesophageal  glands — especially  to- 
wards the  lower  end  of  the  oesophagus. 

COURSE  AND  ^e  right  pneumogastric  nerve  enters  the  chest 

BRANCHES  OF  THE      between  the  subclavian  artery  and  vein,  descends 
PNEUMOGASTRIC        "by  the  side  of  the  trachea,  then  passes  behind  the 
n58'  root  of  the  right  lung  to  the  posterior  surface  of 

the  oesophagus,  upon  which  it  divides  into  branches,  which  form  a 
plexus  (posterior  oesophageal)  upon  that  tube.  The  plexus  then 
reunites  into  a  single  trunk,  which  passes  into  the  abdomen 
through  the  oesophageal  opening  in  the  diaphragm.  The  left 
pneumogastric  descends  into  the  chest  between  the  left  subclavian 
and  carotid  arteries,  and  behind  the  left  brachio-cephalic  vein. 
It  then  crosses  in  front  of  the  arch  of  the  aorta,  and  passes  behind 
the  root  of  the  left  lung  to  the  anterior  surface  of  the  ossophagus, 
upon  which  it  also  forms  a  plexus  (anterior  oesophageal).  The 
branches  of  the  pneumogastric  nerve  in  the  chest  are  as 
follows :  — 

a.  The  inferior  laryngeal  or  recurrent. — This  nerve  on  the  right 
side  turns  under  the  subclavian  and  the  common  carotid  arteries  (p.  61)  ; 
on  the  left,  under  the  arch  of  the  aorta,  below  the  ductus  anteriosus,  and 
ascends  to  the  larynx.  It  passes  beneath  the  inferior  thyroid  artery,  and 
lying  in  the  groove  between  the  trachea  and  oesophagus,  it  enters  the 
larynx  beneath  the  lower  border  of  the  inferior  constrictor  of  the 

L 


146  PXEUMOGASTRIC    IN   THE    CHEST. 

pharynx.  It  supplies  with  motor  nerves  all  the  muscles  which  act  upon 
the  rima  glottidis,  except  the  crico-thyroid  (supplied  by  the  external 
laryngeal  nerve).  As  they  turn  beneath  their  respective  arteries,  they  give 
off  branches  to  the  deep  cardiac  plexus. 

b.  Cardiac  branches. — These  are  very  small,  and  join  the   cardiac 
plexuses;    the  right  arise  from  the  right  recurrent  laryngeal  and  the 
right  pneumogastric,  close  to  the  trachea ;  the  left  come  from  the  left 
recurrent  laryngeal  nerve.    On  both  sides  these  branches  pass  to  the  deep 
cardiac  plexus. 

c.  Pulmonary    branches. — These    accompany   the    bronchial    tubes. 
The  greater  number  run  behind  the  root  of  the  lung,  and  constitute 
the  posterior   pulmonary  plexus.      A  few,  forming  the   anterior   pul- 
monary plexus,  supply  the  front  part  of  the  root  of  the  lung.     Both  these 
plexuses  are  joined  by  filaments  from  the   sympathetic  system.      The 
nerves  of  the  lungs  are,  however,  very  small,  and  cannot  be  traced  far 
into  their  substance.* 

d.  (Esophageal  plexus. — Below  the  root  of  the  lung  each  pneumo- 
gastric nerve  is  subdivided  so  as  to  form  an  interlacement  of  nerves 
round   the   oesophagus   (plexus   guise).       From    this    plexus    numerous 
filaments  supply  the  coats  of  the  tube ;  but  the  majority  of  them  are 
collected  into  two  nerves — the  one,  the  continuation  of  the  left  pneumo- 
gastric nerve  lying  in  front  of  the  oesophagus ;  the  other,  that  of  the  right, 
lying  behind  it.     Both  nerves  pass  through  the  cesophageal  opening  in 
the  diaphragm  for  the  supply  of  the  stomach. 

Having  examined  the  contents  of  the  posterior  mediastinum 
from  the  right  side,  now  do  so  from  the  left.  The  left  lung  should 
be  turned  out  of  its  cavity  and  fastened  by  hooks  towards  the  right 
side.  After  removing  the  pleura,  we  see  the  descending  thoracic 
aorta,  the  pneumogastric  nerve  crossing  the  arch  and  sending 
the  recurrent  branch  under  it ;  also  the  first  part  of  the  left 
subclavian,  covered  externally  by  the  pleura.  The  pneumo- 
gastric nerve  must  be  traced  behind  the  root  of  the  left  lung  to 
the  oesophagus,  and  the  cesophageal  plexus  of  this  side  dissected. 
Lastly,  notice  the  lesser  vena  azygos  which  crosses  under  the  aorta 
aVout  the  sixth  or  seventh  dorsal  vertebra  to  join  the  vena  azygos 
major. 

*  Upon  this  subject,  see  the  beautiful  plates  of  Scarpa. 


SYMPATHETIC    IN    THE    CHEST. 


U7 


THORACIC 
PORTION  OF  THE 
SYMPATHETIC. 


Fig.  26. 


This  portion  of  the  sympathetic  system  is  gene- 
rally composed  of  twelve  ganglia  covered  by  the 
pleura ;  one  ganglion  being  found  over  the  head  of 

each  rib.     Often  there  are  only  ten  ganglia,  in  consequence  of  two 

of  them  uniting  here  and  there.     The 

first  thoracic  ganglion  is  the  largest. 
Each  ganglion  is  connected  by  two 

branches  with  the  corresponding  inter- 
costal nerve.     The  nerves  proceeding 

from    the    ganglia    pass    inwards    to 

supply  the  thoracic  and  part  of  the 

abdominal    viscera.      The    branches 

which   proceed  from    the  four  upper 

ganglia  are  small  and  are  distributed 

as  follows  (see  the  diagram) : — 

a.  Minute  nerves  from  the  first  and 
second  ganglia  to  the  deep  cardiac 
plexus, 

b.  Minute   nerves    from   the   third 
and  fourth  ganglia  to  the  posterior 
pulmonai^y  plexus. 

The  branches  arising  from  the  six 
lower  ganglia  unite  to  form  three  nerves 
— the  great  splanchnic,  the  lesser,  and 
the  smallest  splanchnic  nerves. 

a.  The  great  splanchnic  nerve  is 
generally  formed  by  branches  from  the 
fifth  or  sixth  to  the  tenth  ganglion. 
They  descend  obliquely  along  the  sides 
of  the  bodies  of  the  dorsal  vertebrae, 
and  unite  into  a  single  nerve,  which 
passes  through  the  corresponding  crus 
of  the  diaphragm,  and  joins  the  semilunar  ganglion  of  the  abdo- 
men, sending  also  branches  to  the  renal  and  supra-renal  plexuses. 

b.  The  lesser  splanchnic  nerve  is  commonly  formed  by  branches 
from  the  eleventh  and   twelfth  ganglia.     It  passes  through   the 

x  2 


DIAGRAM  OF  THE   THORACIC    PORTIOX 
OF   THE   SYMPATHETIC. 


148  INTERCOSTAL   VESSELS. 

crus  of  the  diaphragm  to  the  coeliac  plexus,  and  occasionally  to 
the  renal  plexus.* 

c.  The  smallest  splanchnic  nerve  (when  present)  comes  from 
the  twelfth  ganglion,  passes  through  the  crus  of  the  diaphragm,  and 
terminates  in  the  renal  and  coeliac  plexuses.  (This  is  not  repre- 
sented in  the  diagram.) 

INTERCOSTAL  The  intercostal    muscles    occupy  the  intervals 

MUSCLES.  between  the  ribs.     In  each  interval  there  are  two 

layers  of  muscles  which  cross  like  the  letter  X.  The  external 
intercostals  run  obliquely  from  behind  forwards,  like  the  ex- 
ternal oblique  muscle  of  the  abdomen.  The  internal  run  from 
before  backwards,  like  the  internal  oblique.  Observe  that  a  few 
fibres  of  the  inner  layer  pass  over  one  or  even  two  ribs,  chiefly 
near  the  angles,  and  more  especially  of  the  lower  ribs,  and 
terminate  upon  a  rib  lower  down.f 

Neither  of  these  layers  of  intercostal  muscles  extends  all  the 
way  between  the  sternum  and  the  spine :  the  outer  layer,  begin- 
ning at  the  spine,  ceases  at  the  cartilages  of  the  ribs ;  the  inner, 
commencing  at  the  sternum,  ceases  at  the  angles  of  the  ribs. 

The  intercostal  muscles  present  an  intermixture  of  tendinous 
and  fleshy  fibres ;  and  they  are  covered  inside  and  outside  the  chest 
by  a  glistening  fascia,  to  give  gi eater  protection  to  the  intercostal 
spaces. 

The  external  intercostal  muscles  elevate  the  ribs,  and  are 
therefore  muscles  of  inspiration.  The  internal  intercostal  muscles 
depress  the  ribs,  and  are  therefore  muscles  of  expiration. 

INTERCOSTAL  There  are  twelve  intercostal  arteries  on  each  side, 

ARTERIES,  which  lie  between  the  internal  and  external  inter- 

costal muscles,  the  last  excepted.  The  two  upper  arteries  are  sup- 
plied by  the  intercostal  branch  of  the  subclavian ;  the  remaining 
ten  are  furnished  by  the  aorta :  and  since  this  vessel  lies  rather  on 
the  left  side  of  the  spine,  the  right  intercostal  arteries  are  longer 
than  the  left.  The  upper  intercostal  arteries  from  the  aorta  ascend 

*  In  a  few  instances  we  have  traced  a  minute  filament  from  one  of  the  ganglia 
into  the  body  of  a  vertebra.     According  to  Cruveilhier  each  vertebra  receives  one. 
f  These  irregular  muscular  bundles  are  called  the  subcostal  muscles. 


INTERCOSTAL   VESSELS.  149 

obliquely  to  reach  their  intercostal  spaces  ;  the  lower  run  more  trans- 
versely. As  they  pass  outwards,  they  are  covered  by  the  pleura  and 
the  sympathetic  nerves ;  the  right,  in  addition,  pass  behind  the  oeso- 
phagus, thoracic  duct,  and  the  vena  azygos  major.  Having  reached 
the  intercostal  space,  each  artery  divides  into  an  anterior  and  a 
posterior  branch.  The  anterior  branch  in  direction  and  size  appears 
to  be  the  continuation  of  the  common  trunk.  At  first  it  runs  along 
the  middle  of  the  intercostal  space,  lying  upon  the  external  inter- 
costal muscle,  and  separated  from  the  cavity  of  the  chest  by  the  pleura 
and  intercostal  fascia.  Here,  therefore,  it  is  liable  to  be  injured  by 
a  wound  in  the  back.  But  near  the  angle  of  the  rib  it  passes 
•between  the  intercostal  muscles,  and  occupies  the  groove  in  the 
lower  border  of  the  rib  above.  Here  it  gives  off  a  small  branch, 
the  collateral  intercostal,  which  runs  for  some  distance  along  the 
upper  border  of  the  rib  below.  After  supplying  the  muscles,  the 
main  trunk  anastomoses  with  the  anterior  intercostal  branch  of  the 
internal  mammary  artery.  In  some  cases  this  branch  is  as  large 
as  the  intercostal  itself,  and  situated  so  as  to  be  directly  exposed  to 
injury  in  the  operation  of  tapping  the  chest. 

In  its  course  along  the  intercostal  space,  each  artery  sends 
branches  to  the  intercostal  muscles  and  the  ribs.  About  midway 
between  the  sternum  and  the  spine,  each  gives  off  a  small  branch, 
which  accompanies  the  lateral  cutaneous  branch  of  the  inter- 
costal nerve.  The  continued  trunk,  gradually  decreasing  in  size, 
becomes  very  small  towards  the  anterior  part  of  the  space,  and  is 
placed  more  in  the  middle  of  it.  Those  of  the  true  intercostal 
spaces  inosculate  with  branches  of  the  internal  mammary,  and 
thoracic  branches  of  the  axillary ;  those  of  the  false  run  between 
the  layers  of  the  abdominal  muscles,  and  anastomose  with  the 
epigastric  and  lumbar  arteries. 

The  posterior  or  dorsal  branch  passes  backwards  between  the 
transverse  processes  of  the  vertebrae,  on  the  inner  side  of  the 
anterior  costo-trans verse  ligament,  and  is  distributed  to  the  muscles 
and  skin  of  the  back.  Each  sends  an  artery  through  the  inter- 
vertebral  foramen  to  the  spinal  cord  and  its  membranes. 

On  the  right  side  the  intercostal  veins  terminate  in  the  vena 


150 


INTERCOSTAL   NERVES. 


FIG.  27. 


azygos  major ;  on  the  left,  the  seven  or  eight  lower  terminate  in  the 
vena  azygos  minor,  the  remainder  in  the  left  superior  intercostal  vein. 
The  usual  relation  which  the  intercostal  vessels  and  nerve 
bear  to  each  other  in  the  intercostal  space,  is,  that  the  vein  lies 
uppermost,  the  nerve  lowest,  and  the  artery  between  them. 

INTERCOSTAL  These  are  twelve  in  number,  and  are  the  anterior 

NERVES.  divisions  of  the  dorsal  spinal  nerves.     Each  dorsal 

nerve  (like  all  the  spinal  nerves)  arises  from  the  spinal  cord  by  two 
roots,  an  anterior  or  motor,  and  a  posterior  or  sensory.  The  sen- 
sory root  has  a  ganglion  upon  it.  The  two  roots  unite  in  the 
intervertebral  foramen  and  form  a  compound  nerve.  After  passing 

through  the  foramen,  it  is  connec- 
ted by  two  filaments  with  the  sym- 
pathetic nerve,  and  then  divides  into 
an  anterior  and  a  posterior  branch. 
The  posterior  branches  pass  back- 
wards between  the  transverse  pro- 
cesses of  the  dorsal  vertebrae,  and 
supply  the  muscles  of  the  back. 
The  anterior  branches  (the  proper 
intercostal  nerves)  proceed  between 
the  intercostal  muscles  in  company 
with,  and  immediately  below,  their 
corresponding  arteries.  In  the  an- 
terior part  of  the  intercostal  space 
the  nerves  lie  in  the  substance  of 
the  internal  intercostal  muscles,  and 
at  the  costal  cartilages  run  through  the  muscles,  passing  in  front 
of  the  triangularis  sterni  and  the  internal  mammary  artery.  Midway 
between  the  spine  and  the  sternum,  they  give  off  lateral  cutaneous 
branches,  which  supply  the  skin  over  the  scapula  and  the  thorax. 
The  intercostal  nerves  terminate  in  front  in  the  anterior  cutaneous 
nerves ;  the  six  upper,  coming  through  their  respective  intercostal 
spaces,  supply  the  skin  over  the  chest ;  the  six  lower  terminate 
in  the  front  wall  of  the  abdomen,  near  the  linea  alba. 

Notice  that   the   first  dorsal   nerve   ascends    nearly  perpen- 


DIAGRAM  OF  A  SPINAL  NERVK. 


PULMONARY   ARTERY.  151 

dicularly  over  the  neck  of  the  first  rib  to  form  part  of  the  brachial 
plexus.  Before  doing  so,  it  sends  a  nerve  to  the  first  intercostal 
space.  This,  as  a  rule,  has  no  lateral  cutaneous  branch. 

Intercostal  lymphatic  glands. — These  are  situated  near  the 
heads  of  the  ribs ;  there  are  some  between  the  layers  of  the  inter- 
costal muscles.  They  are  of  small  size,  and  their  efferent  vessels  go 
into  the  thoracic  duct.  We  have  seen  these  intercostal  glands  en- 
larged and  diseased  in  phthisis. 

BBONCHIAL  AND         Small  bronchial  arteries,  arising  on  the  right 
(ESOPHAGEAL  side  most  frequently  from  the  first  aortic  intercos- 

ARTERIES.  tal  (3rd  intercostal)  artery,  and  on  the  left  from 

the  thoracic  aorta,  accompany  the  bronchial  tube  on  its  posterior 
aspect  into  the  substance  of  the  lung.*  Their  distribution  and 
office  will  be  considered  with,  the  anatomy  of  the  lung.  (Esopha- 
geal  arteries  four  or  five  in  number  proceed  from  the  front  of  the 
thoracic  aorta  to  ramify  on  the  oesophagus,  where  they  inoscu- 
late above  with  the  cesophageal  branches  of  the  inferior  thyroid, 
and  below  with  the  coronaria  ventriculi  and  phrenic  arteries. 
Small  posterior  mediastinal  arteries  axe  given  off  from  the 
posterior  part  of  the  aortar  and  supply  the  lymphatic  glands  and 
tissues  of  the  posterior  mediastinum. 

Having  finished  the  posterior  mediastinum,  replace  the  lung, 
and  turn  your  attention  once  more  to  the  great  vessels  at  the  root 
of  the  heart. 

PULMONARY  This  vessel  is  about  two  inches  in  length,  and 

ARTERY.  conveys  the  venous  blood  from  the  heart  to  the 

lungs.  It  proceeds  from  the  upper  part  of  the  right  ventricle,  and 
passes  upwards  and  backwards  along  the  left  side  of  the  aorta  to 
the  concavity  of  the  arch  of  the  aorta,  where  it  divides  into 
two  branches,  a  right  and  a  left,' one  for  each  "lung.  At  its  origin 
it  has  on  each  side  an  auricular  appendix  and  a  coronary  artery, 
and  lies  in  front  of  the  root  of  the  aorta.  The  pulmonary  artery 
and  the  aorta  are  surrounded  for  two  inches  by  a  common  sheath  of 

*  On  the  left  side  there  are  usually  two  bronchial  arteries — a  superior,  arising 
from  the  highest  part  of  the  thoracic  aorta,  and  an  inferior,  arising  about  an  inch 
lower  down. 


152  NEEVES  OF  THE  HEART. 

pericardium.  The  right  branch,  the  larger  and  longer,  passed 
below  the  arch  of  the  aorta  to  the  lung ;  the  left  is  easily  followed 
to  its  lung  by  removing  the  layer  of  pericardium  investing  it. 

Search  should  be  made  for  a  short  fibrous  cord  which  connects 
the  commencement  of  the  left  pulmonary  artery  with  the  concavity 
of  the  arch  of  the  aorta.  This  cord  is  the  remains  of  the  ductus 
arteriosus,  a  canal  which  in  fcetal  life  conveyed  blood  from  the 
pulmonary  artery  to  the  aorta. 

Draw  towards  the  left  side  the  first  part  of  the  arch  of  the  aorta, 
and  dissect  the  pericardium  from  the  great  vessels  at  the  base  of 
the  heart.  Thus  a  good  view  will  be  obtained  of  the  trachea  and 
its  bifurcation  into  the  two  bronchi.  Below  the  division  of  the 
trachea  the  right  pulmonary  artery  is  seen  passing  in  front  of  the 
right  bronchus.  The  superior  vena  cava  and  aorta  are  seen  in 
front  of,  and  nearly  at  right  angles  to,  the  right  pulmonary  artery. 
The  vena  azygos  is  seen  arching  over  the  right  bronchus  and  ter- 
minating in  the  vena  cava  superior.  Notice,  especially,  a  number 
of  lymphatic  glands  called  bronchial,  at  the  angle  of  bifurcation 
of  the  trachea.  The  situation  of  these  glands  in  the  midst  of  so 
many  tubes  explains  the  variety  of  symptoms  which  may  be  pro- 
duced by  their  enlargement. 

NERVES  OF  THE  The  nerves  of  the  heart  come  from  the  pneumo- 
HEABT  AND  OAK-  gastric  and  its  recurrent  branch,  and  the  three 
MAC  PLEXUSES.  cervical  ganglia  of  the  sympathetic.  The  pneumo- 
gastric  gives  off  (generally)  two  or  more  filaments  (cardiac)  which 
proceed  from  the  main  trunk  in  the  neck,  or  from  its  recurrent 
branch.  The  sympathetic  sends  three  (cardiac)  filaments  ;  one 
from  the  upper  cervical  ganglion,  a  second  from  the  middle,  and 
a  th'ird  from  the  lower ;  and  they  are  called,  lespectively,  the  upper, 
middle,  and  lower  cardiac  nerves  of  the  sympathetic. 

The  minute  and  delicate  nerves  from  these  several  sources  on 
each  side,  pass  downwards  to  the  base  of  the  heart.  They  vary  very 
much  in  their  precise  relations  to  the  great  vessels  upon  which 
they  run  ;  but  speaking  generally,  it  may  be  said  that  the  nerves 
on  the  right  side  run  chiefly  behind  the  arch  of  the  aorta,  those 
on  the  left,  in  front  of  it.  Eventually  they  form,  by  their  mutual 


NERVES  OF  THE  HEART.  153 

Subdivisions  and  interlacement,  an  intricate  network  of  nerves, 
termed,  according  to  their  position,  the  deep  and  the  superficial 
cardiac  plexus. 

The  deep  and  larger  cardiac  plexus  is  situated  behind  the 
arch  of  the  aorta  in  front  of  the  bifurcation  of  the  trachea,  and 
immediately  above  the  right  pulmonary  artery.  To  see  it,  the 
pericardial  covering  of  the  aorta  must  be  carefully  removed,  and 
the  vessel  hooked  forwards  and  to  the  left. 

The  superficial  and  smaller  cardiac  plexus  lies  in  the  con- 
cavity of  the  arch  of  the  aorta  in  front  of  the  right  pulmonary 
artery.  It  is  closely  connected  with  the  deep  plexus  ;  and  (gene- 
rally) receives  the  upper  cardiac  branch  of  the  left  sympathetic, 
and  the  lower  cardiac  branch  from  the  left  pneumogastric. 

From  the  cardiac  plexuses,  as  a  common  centre,  the  nerves  pass 
off  to  the  heart,  forming  plexuses  around  the  coronary  arteries. 
Thus,  the  anterior  coronary  plexus  (derived  chiefly  from  the 
superficial  cardiac)  accompanies  the  anterior  coronary  artery.  The 
posterior  coronary  plexus  (derived  chiefly  from  the  left  side  of 
the  deep  cardiac)  runs  with  the  posterior  coronary  artery.  The 
two  plexuses  communicate  at  the  apex  of  the  heart,  and  in  the 
ventricular  septum. 

It  is  not  an  easy  matter  to  trace  the  nerves  into  the  substance 
of  the  heart.  For  this  purpose  a  horse's  heart  is  the  best,  and 
previous  maceration  in  water  is  desirable.  The  nerves  in  the 
substance  of  the  heart  are  peculiar  in  this  respect ;  that  they 
present  minute  ganglia  in  their  course,  which  are  presumed  to 
preside  over  the  rhythmical  contractions  of  the  heart. 

CONSTITUENTS  Draw    aside    the   margin   of  the    right   lung; 

OF  THE  ROOT  OF  divide  the  superior  vena  cava  above  the  vena 
EACH  LUNG.  azygos,  and  turn  down  the  lower  part.  Remove 

the  layer  of  pericardium  which  covers  the  pulmonary  veins,  and 
the  constituent  parts  of  the  root  of  the  right  lung  will  be  exposed. 
It  is  composed  of  the  pulmonary  artery,  the  pulmonary  veins, 
bronchus,  bronchial  vessels,  anterior  and  posterior  pulmonary 
plexuses,  and  some  lymphatics.  The  following  is  the  disposition  of 
the  large  vessels  forming  the  root  of  the  lung.  In  front  are  the 


154 


CONSTITUENTS    OP   THE    ROOT   OF   EACH    LUNG. 


two  pulmonary  veins :  behind  the  veins  are  the  subdivisions  of 
the  pulmonary  artery  ;  behind  the  artery  are  the  divisions  of  the 
bronchus.  From  above  downwards  they  are  disposed  thus  : — On 


FIG.  28. 


DIAGRAM  SHOWING  THE  CONSTITUENTS  OF  THE  BOOT  OF  EACH  LUNG,  AND  THEIR 
RELATIYE  POSITION '.  ALSO  THE  POSITION  OF  THE  TALTES  OF  THE  HEART.  THE 
ARROWS  INDICATE  THE  DIRECTIONS  IN  WHICH  AORTIC  AND  MITRAL  MURMURS  ARE 
PROPAGATED. 


the  right  side  we  find — 1st,  the  bronchus;  2nd,  the  artery;  3rd, 
the  veins.  On  the  left,  we  find: — 1st,  the  artery;  2nd,  the 
bronchus ;  3rd,  the  veins — as  shown  in  fig.  28. 


DISSECTION    OF    THE    HEART.  155 

DISSECTION   OF  THE  HEART. 

The  heart  is  conical  in  form,  and  more  or  less  convex  on  its 
external  aspect,  with  the  exception  of  that  portion  lying  on  the 
tendinous  centre  of  the  diaphragm,  which  is  flattened.  It  is 
situated  obliquely  in  the  thorax,  and  is  completely  surrounded  by 
the  pericardium.  It  extends  from  the  fourth  to  the  eighth  dorsal 
vertebra,  with  its  base  directed  upwards  and  to  the  right,  its  apex 
downwards  and  to  the  left.  The  position  which  the  heart  bears 
to  the  thoracic  walls  has  been  already  described  (pp.  134-137) ;  it 
varies  however  in  different  subjects,  and  as  a  rule  is  higher  in  the 
dead  body  than  during  life,  owing  to  the  shrinking  of  the  lungs. 

Notice  the  two  longitudinal  grooves  (sulci}  on  the  front  and 
back  surfaces  of  the  heart,  indicating  the  septum  between  the  two 
ventricles  ;  the  anterior  groove  lies  nearer  to  the  left  side,  the 
posterior,  to  the  right  side  of  the  heart. 

A  circular  groove,  nearer  the  base,  marks  the  separation  between 
the  auricles  and  the  ventricles.  In  the  circular  and  longitudinal 
furrows,  surrounded  by  more  or  less  fat,  run  the  coronary  vessels, 
the  nerves  and  the  lymphatics. 

SIZE  AND  The  size  of  the   heart   is   dependent  upon  so 

WEIGHT.  many  conditions,  that  the  following  measurements 

must  be  received  with  more  or  less  limitation.  An  average  heart  will 
measure  in  its  transverse  direction  at  the  base,  three  and  a  half 
inches ;  in  its  length,  about  five  inches ;  in  its  thickness,  two  and  a 
half  inches.  The  weight  is  from  ten  to  twelve  ounces  in  the  male, 
and  from  eight  to  ten  in  the  female,  but  much  depends  upon  the 
size  and  condition  of  the  body  generally.  As  a  rule,  the  heart 
gradually  increases  in  length,  breadth,  and  thickness  from  child- 
hood to  old  age.* 

The  heart  is  a  double  hollow  muscular  organ ;  that  is,  it  is 
composed  of  two  hearts,  a  right  and  a  left,  separated  by  a  septum, 
and  not  communicating  with  each  other  except  during  uterine, 
and  rarely  in  adult,  life.  Each  half  consists  of  two  cavities,  an 
auricle  and  a  ventricle,  which  communicate  by  a  wide  orifice, 

*  Bizot,  'Mem.  de  la  Soc.  Med.  d'Observ.  de  Paris,'  torn.  i.  1836. 


156  DISSECTION  OP  THE  HEAET. 

the  auriculo-ventricular  opening.  The  right  half  of  the  heart 
propels  venous  blood  to  the  lungs,  and  is  called  the  pulmonary; 
the  left  propels  arterial  blood  from  the  lungs  throughout  the 
body,  and  is  called  the  systemic.  These  two  hearts  are  not 
placed  apart,  because  important  advantages  result  from  their 
union.  By  being  enclosed  in  a  single  bag  they  occupy  less  room 
in  the  chest ;  and  the  action  of  their  corresponding  cavities  being 
precisely  synchronous,  their  fibres,  mutually  intermixing,  contribute 
to  their  mutual  support. 

The  cavities  of  the  heart  should  now  be  examined  in  the  order 
in  which  the  blood  circulates  through  them. 

This  is  situated  at  the  right  side  of  the  base  of 
the  heart,  and  forms  a  quadrangular  cavity,  the 
atrium  or  sinus  venosus,  between  the  two  venae  cavse,  from  which 
it  receives  the  blood.  From  its  front,  a  small  pouch  projects 
towards  the  left,  and  overlaps  the  root  of  the  aorta ;  this  part  is 
termed  the  '  appendix '  of  the  auricle,  and  resembles  a  dog's  ear  in 
shape. 

To  see  the  interior,  make  a  horizontal  incision  through  the 
anterior  wall  from  the  apex  of  the  appendix,  transversely  across 
the  cavity :  from  this  make  another  upwards  at  right  angles  into 
the  superior  vena  cava.  The  interior  is  lined  by  a  polished  mem- 
brane called  the  '  endocardium,'  and  is  everywhere  smooth  except 
in  the  appendix,  where  the  muscular  fibres  are  collected  into 
bundles,  called,  from  their  resemblance  to  the  teeth  of  a  comb, 
'  musculi  pectinati.'  They  radiate  from  the  auricle  to  the  edge 
of  the  auriculo-ventricular  opening. 

Examine  carefully  the  openings  of  the  two  venae  cavse :  they 
are  not  directly  opposite  to  each  other ;  the  superior  is  situated  on 
a  plane  rather  in  front  and  a  little  to  the  left  of  the  inferior,  that 
the  streams  of  blood  may  not  meet.  The  inferior  cava,  after  passing 
through  the  tendinous  centre  of  the  diaphragm,  makes  a  slight 
curve  to  the  left  before  it  opens  into  the  auricle,  that  the  stream  of 
its  blood  may  be  directed  towards  the  auriculo-ventricular  opening. 
The  orifice  of  each  vena  cava  is  nearly  circular,  and  surrounded 
by  circular  muscular  fibres  continuous  with  those  of  the  auricle. 


DISSECTION   OF   THE   HEART.  157 

The  posterior  wall  of  the  auricle  is  formed  by  the  partition 
between  the  auricles,  the  '  septum  auricular um.'  Upon  this 
septum,  above  and  to  the  left  of  the  orifice  of  the  vena  cava 
inferior,  is  an  oval  depression  (fossa  ovalis),  bounded  by  a  pro- 
minent border  (annulus  ovalis).  This  depression  indicates  the 
remains  of  the  opening  (foramen  ovale]  through  which  the 
auricles  communicated  in  foetal  life.  After  birth  this  opening- 
closes  ;  but  if  the  closure  is  imperfect,  the  stream  of  dark  blood 
in  the  right  auricle  mixes  with  the  florid  blood  in  the  left,  and 
occasions  what  is  called  '  cyanosis.''  A  valvular  communica- 

FIG.  29. 


Auriculo-ventricular  orifice .    . 

Fossa  ovalis 

Opening  of  the  coronary  vein  . 
Line  of  Eustachian  valve.    .    . 


DIAGRAM    OF    THE    INTERIOR   OF    THE    RIGHT    AURICLE. 

tion,  however,  not  infrequently  exists  between  the  auricles  in 
this  situation  which  is  not  attended  with  indications  of  this 
disease. 

A  more  or  less  noticeable  fold  of  the  lining  membrane  may  be 
seen  projecting  from  the  front  margin  of  the  v.  c.  inferior  to 
the  front  border  of  the  fossa  ovalis.  It  is  the  remnant  of  the 
'  Eustachian*  valvej  which  was  of  considerable  size  in  foetal  life, 
and  served  to  direct  the  current  of  blood  from  the  v.  c.  inferior, 
through  the  foramen  ovale,  into  the  left  auricle. 

*  Eustachius,  'Libell.  de  vena  sine  pari.' 


158  DISSECTION    OF    THE    HEART. 

To  the  left  of  the  Eustachian  valve,  that  is,  between  its  remains 
and  the  auriculo-ventricular  opening,  is  the  orifice  of  the  coronary 
vein ;  it  is  guarded  by  a  semicircular  valve,  called  '  valvula  The- 
besiij  to  prevent  regurgitation  of  the  blood  during  the  auricular 
contraction.  Here  and  there  upon  the  posterior  wall  of  the  auricle 
may  be"  observed  minute  openings  called  'foramina  Thebesii : ' 
some  being  the  orifices  of  small  veins  returning  blood  from  the 
substance  of  the  heart ;  others  being  simple  depressions  in  the 
muscular  tissue.  To  the  left,  and  rather  in  front  of  the  orifice  of 
the  vena  cava  inferior,  is  the  auriculo-ventricular  opening  guarded 
by  the  tricuspid  valve.  It  is  oval  in  form,  and  will  admit  the 
passage  of  three  fingers.  Lastly,  between  the  orifices  of  the  supe- 
rior and  inferior  venae  cavae  is  a  rounded  elevation,  the  tubercle  of 
Lower  (not  seen  in  the  diagram),  which  is  supposed  to  direct  the 
current  of  blood  in  foetal  life,  from  the  superior  cava  to  the  auri- 
culo-ventricular opening. 

EIGHT  YEN-  This  forms  the    right  border    and  about  two- 

TRICLE.  thirds   of  the   front   surface   of  the   heart.      To 

examine  its  interior,  a  triangular  flap  should  be  raised  from  its 
anterior  wall.  The  apex  of  this  flap  should  be  below  :  one  cut 
along  the  right  edge  of  the  ventricle,  the  other  along  the  line  of 
the  ventricular  septum.  Observe  that  the  wall  of  the  ventricle  is 
much  thicker  than  that  of  the  auricle.  The  cavity  of  the  ventricle 
is  conical,  with  its  base  upwards  and  to  the  right.  From  its  walls 
project  bands  of  muscular  fibres,  '  columnce  carnecej  of  various 
length  and  thickness,  which  cross  each  other  in  every  direction ; 
this  muscular  network  is  generally  filled  with  coagulated  blood. 
Of  these  columnae  carneae  there  are  three  kinds :  one,  stands  out  in 
relief  from  the  ventricle  ;  another  is  attached  to  the  ventricle  by 
its  extremities  only,  the  intermediate  portion  being  free ;  a 
third,  and  by  far  the  most  important  set,  called  '  musculi  papil- 
laresj  is  fixed  by  one  extremity  to  the  wall  of  the  ventricle,  while 
the  other  extremity  gives  attachment  to  the  fine  tendinous  cords, 
'  cordos  tendinecej  which  regulate  the  action  of  the  tricuspid  valve. 
The  number  of  these  musculi  papillares  is  equal  to  the  number  of 
the  chief  segments  of  the  valve  ;  consequently  there  are  three  in 


DISSECTION   OP   THE    HEA'IT.  159 

the  right  and  two  in  the  left  ventricle.  Of  those  in  the  right 
ventricle,  one  proceeds  from  the  septum. 

There  are  two  openings  in  the  right  ventricle.  One,  the 
auriculo-wentricular,  through  which  the  blood  passes  from  the 
auricle,  is  oval  in  form  and  placed  at  the  base  of  the  ventricle. 
It  is  surrounded  by  a  ring  of  fibrous  tissue,  to  which  is  attached 
the  tricuspid  valve.  From  the  upper  and  front  part  of  the  ven- 
tricle, a  smooth  passage,  '  infundibulum '  or  '  conus  arteriosusj 
leads  to  the  opening  of  the  pulmonary  artery.  It  is  situated  to  the 
left  and  in  front  of  the  auriculo- ventricular  opening,  and  about 
three-fourths  of  an  inch  higher. 

TRICUSPID  This  is  situated  at  the   right  auriculo-ventri- 

VALVE.  cular  opening,  and    consists    of   three   principal 

triangular  flaps,  and  besides  these,  of  intermediate  flaps  of  smaller 
size.  Like  all  the  valves  of  the  heart,  it  is  formed  by  a  fold  of 
the  lining  membrane  (endocardium)  of  the  heart  strengthened 
by  fibrous  tissue,  in  which  a  few  muscular  fibres  may  be  demon- 
strated. The  bases  of  the  valves  are  continuous  with  one  another, 
so  that  they  form  a  membranous  ring  between  the  auricle  and 
ventricle,  while  the  segments  project  into  the  cavity  of  the  right 
ventricle.  Of  its  three  principal  flaps,  the  largest  or  anterior  is 
so  placed,  that,  when  not  in  action,  it  partially  covers  the  orifice 
of  the  pulmonary  artery ;  another,  the  internal,  corresponds  with  the 
inferior  wall  of  the  ventricle  ;  the  third,  or  posterior,  rests  upon  the 
septum  ventriculorum. 

Observe  the  arrangement  of  the  tendinous  cords  which  regulate 
the  action  of  the  valve.  First,  they  are  all  attached  to  the  ven- 
tricular surface  of  the  valve.  Secondly,  the  tendinous  cords 
proceeding  from  a  given  papillary  muscle  are  attached  to  the 
adjacent  halves  of  two  of  the  larger  flaps,  and  to  a  smaller  inter- 
mediate one ;  consequently,  when  the  ventricle  contracts,  and  the 
papillary  muscle  also,  the  adjacent  borders  of  the  flaps  will  be 
approximated.  Thirdly,  to  insure  the  strength  of  every  part  of 
the  valve,  the  tendinous  cords  are  inserted  at  three  different  points 
of  it  in  straight  lines ;  accordingly,  they  are  divisible  into  three 
sets.  Those  of  the  first,  which  are  three  or  four  in  number,  are 


160  DISSECTION   OP   THE    HEART. 

attached  to  the  base  of  the  valve  ;  those  of  the  second,  from  four 
to  six,  proceed  to  the  middle  of  its  ventricular  surface ;  those  of 
the  third,  which  are  the  smallest  and  most  numerous,  are  attached 
to  its  free  margin.* 

PULMONARY  OB          These  are  three  membranous  folds,  like  watch- 
SEMILUNAB  pockets,  situated  at  the  orifice  of  the  pulmonary 

VALVES.  artery.     They  are  attached  to  the  fibrous  ring  at 

the  root  of  the  artery ;  their  free  edges  look  upwards,  and  present 
a  festooned  border,  in  the  centre  of  which  is  a  small  cartilagi- 
nous body  called  the  nodulus  or  corpus  Arantii.]  The  use 
of  these  bodies  is  plain.  Since  the  valves  are  semilunar, 
when  they  fall  together  they  would  not  exactly  close  the  artery ; 
there  would  be  a  space  of  a  triangular  form  left  between  them 
in  the  centre,  just  as  there  is  when  we  put  the  thumb,  fore,  and 
middle  fingers  together.  This  space  is  filled  up  by  these  no- 
dules, so  that  the  closure  becomes  complete. 

The  valves  are  composed  of  folds  of  the  endocardium,  or 
lining  membrane  of  the  heart.  Between  the  folds  is  a  thin  layer 
of  fibrous  tissue,  which  is  prolonged  from  the  fibrous  ring  at 
the  orifice  of  the  artery.  This  layer  of  fibrous  tissue,  however, 
reaches  the  free  edge  of  the  valve  at  three  points  only :  namely,  at 
the  centre,  or  corpus  Arantii,  and  at  each  extremity.  Between  these 
points  it  stops  short,  and  leaves  a  crescent-shaped  portion  of  the  valve 
which  is  thinner  than  the  rest,  and  consists  of  the  endocardial  mem- 
brane. This  crescent-shaped  portion,  called  the  lunula,  is  not  wholly 

*  The  best  mode  of  showing  the  action  of  the  valve  is  to  introduce  a  glass  tube 
into  the  pulmonary  artery,  and  then  to  pour  water  through  it  into  the  ventricle  until 
the  cavity  is  quite  distended.  By  gently  squeezing  the  ventricle  in  the  hand,  so  as 
artificially  to  imitate  its  natural  contraction,  the  tricuspid  valve  will  flap  back  like  a 
flood-gate,  and  close  the  auriculo-vontricular  opening.  In  this  way  one  can  understand 
how,  when  the  ventricle  contracts,  the  blood  catches  the  margin  of  the  valve,  and  by 
its  pressure  gives  it  the  proper  distension  and  figure  requisite  to  block  up  the  aperture 
into  the  auricle.  It  is  obvious  that  the  tendinous  cords  will  prevent  the  valve  from 
flapping  back  into  the  auricle ;  and  this  purpose  is  assisted  by  the  papillary  muscles, 
which  nicely  adjust  the  degree  of  tension  of  the  cords  at  a  time  when  they  would 
otherwise  be  too  much  slackened  by  the  contraction  of  the  ventricle. 

f  So  called  after  Arantius,  an  Italian  anatomist,  who  lived  towards  the  close  of 
the  sixteenth  century. 


DISSECTION   OP   THE    HEART.  161 

without  fibrous  tissue ;  a  thin  tendinous  cord  runs  along  its  free 
edge,  to  give  it  additional  strength  to  resist  the  pressure  of  the 
blood.  Behind  each  of  the  valves  the  artery  bulges  and  forms 
three  slight  dilatations  called  the  sinuses  of  Valsalva.*  These, 
we  shall  presently  see,  are  more  marked  at  the  orifice  of  the  aorta. 
The  action  of  these  valves  is  plain.  During  the  contraction 
of  the  ventricle  the  valves  lie  against  the  side  of  the  artery,  and 
offer  no  impediment  to  the  current  of  blood ;  during  its  dilatation, 
the  elasticity  of  the  distended  artery  would  force  back  the  column 
of  blood,  but  that  the  valves,  being  caught  by  the  refluent  blood, 
bag,  and  fall  together  so  as  to  close  the  tube.  The  greater  the 
pressure,  the  more  accurate  is  the  closure.  The  coats  of  the 
artery  are  very  elastic  and  yielding,  while  the  valve,  like  the 
circumference  to  which  it  is  attached,  is  quite  unyielding ;  conse- 
quently, when  the  artery  is  distended  by  the  impulse  of  the  blood, 
its  wall  is  removed  from  the  contact  of  the  free  margin  of  the 
valves,  and  these  are  the  more  readily  caught  by  the  regurgitating 
motion  of  the  blood.  The  force  of  the  reflux  is  sustained  by  the 
tendinous  part  of  the  valves,  and  by  the  muscular  wall  of  the 
ventricle  (probably  in  a  state  of  contraction).  The  valves  are 
capable  of  sustaining  a  weight  of  sixty-three  pounds  before  they 
give  way.f  The  thinner  portions  (lunulce)  become  placed  so  as  to 
lie  side  by  side,  each  one  with  that  of  the  adjacent  valve.  This 
may  be  demonstrated  by  filling  the  artery  with  water. 

This  is  situated  at  the  left  side  and  posterior 
part  of  the  base  of  the  heart,  and  is  somewhat 
smaller  than  the  right  auricle.  It  is  quadrilateral  and  receives 
the  four  pulmonary  veins,  two  on  either  side,  which  return  the 
oxygenated  blood  from  the  lungs.  From  its  upper  and  left  side,  the 
auricular  appendage  projects  towards  the  right,  curling  over  the 
root  of  the  pulmonary  artery.  The  auricle  should  be  opened  by  a 
horizontal  incision  from  one  pulmonary  vein  to  another :  from  this 
a  second  should  be  made  into  the  appendix.  Its  interior,  the 
atrium,  is  smooth  and  flat,  excepting  in  the  appendix,  which 
contains  the  musculi  pectinati.  Notice  the  openings  of  the  four 
*  An  Italian  anatomist,  b.  1666,  d.  1723.  t  Haller. 

M 


162  DISSECTION    OF   THE    HEAET. 

pulmonary  veins.  Upon  the  septum  between  the  auricles  is  a 
semilunar  depression  indicating  the  remains  of  the  foramen  ovale. 
At  the  lower  and  front  part  of  the  auricle  is  the  auriculo-ventri- 
cular opening.  It  is  oval,  with  its  long  axis  nearly  transverse, 
and  in  the  adult  will  admit  the  passage  of  two  fingers. 

LEFT  VEN-  This  occupies  the  left  border,  and  forms   the 

TEICLE.  apex  of  the  heart.     One  third  of  it  only  is  seen 

on  the  anterior  surface,  the  rest  being  on  the  posterior.  To 
examine  the  interior,  raise  a  triangular  flap,  with  the  apex  below, 
from  its  front  wall.  Observe  that  its  wall  is  about  three  times 
as  thick  as  that  of  the  right  ventricle,  and  that  this  thickness 
gradually  diminishes  towards  the  apex.  The  interior  of  the  left 
ventricle  so  closely  resembles  that  of  the  right  that  there  is  no 
necessity  to  describe  it  in  detail.  The  auricula-ventricular  valve 
consists  of  only  two  principal  flaps :  hence  its  name  mitral  or 
bicuspid.  The  larger  of  these  flaps  is  placed  between  the  aortic 
and  auriculo-ventricular  orifices.  There  are  only  two  musculi 
papillares ;  one  attached  to  the  anterior,  the  other  to  the  posterior 
wall  of  the  ventricle.  They  are  thicker  and  their  chordae,  tendinece 
stronger  than  those  of  the  right  ventricle,  but  their  arrangement 
is  precisely  similar.  From  the  upper  and  back  part  of  the  ven- 
tricle, a  smooth  passage  leads  to  the  orifice  of  the  aorta.  This 
orifice  is  placed  in  the  groove  between  the  two  auricles,  and  some- 
what in  front  and  to  the  right  side  of  the  left  auriculo-ventricular 
opening.  The  two  orifices  are  close  together,  and  only  separated 
by  the  larger  flap  of  the  mitral  valve.  The  aortic  orifice  is 
guarded  by  three  semilunar  valves,  of  which  the  arrangement, 
structure,  and  mode  of  action  are  similar  to  those  of  the  pulmonary 
artery.  Their  framework  is  proportionately  stronger,  consistently 
with  the  greater  strength  "of  the  left  ventricle,  and  the  greater 
impulse  of  the  blood.  In  the  sinuses  of  Valsalva  are  observed 
the  orifices  of  the  two  coronary  arteries. 

The    circumferences   of  the  four    orifices   are 

oIZE  OF  THE 

AUBICULO-VENTEI-  as  follows  i  that  of  the  tricuspid  orifice,  4*74  inches ; 
CULAB  AND  ABIE-  that  of  the  mitral  4  inches ;  that  of  the  pulmonary, 
EIAL  OPENINGS.  ^^  incheg  .  and  thftt  of  the  aortic?  3^4  inches.* 

*  Dr.  Peacock,  '  Croonian  Lectures,'  1865. 


DISSECTION   OP   THE    HEART.  163 

COBONABY  The  heart  is  supplied  with  blood  by  the  two 

AETEEIES.  coronary  arteries,  a  right  or  posterior,  and  a  left  or 

anterior.  They  are  about  the  size  of  a  crow's  quill.  Both  arise 
from  the  aorta  just  above  the  free  margins  of  the  two  anterior 
semilunar  valves,  and  thus  always  allow  the  passage  of  blood ; 
both  run  in  the  furrows  on  the  surface  of  the  heart ;  both  are 
accompanied  by  the  cardiac  nerves  and  by  lymphatics. 

The  anterior  or  left  coronary  artery,  the  smaller  of  the  two, 
arises  from  the  left  side  of  the  aorta.  It  appears  between  the 
pulmonary  artery  and  the  appendix  of  the  left  auricle,  and  then 
divides  into  two  branches :  one  which  seems  the  continuation  of 
the  main  trunk  and  runs  down  the  inter-ventricular  furrow  on 
the  anterior  surface  of  the  heart  to  the  apex;  the  other  passes 
transversely  to  the  left,  in  the  left  auriculo-ventricular  groove  to 
the  back  of  the  heart. 

The  posterior  or  right  coronary  artery  arises  from  the  right 
side  of  the  aorta,  and  descends  obliquely  between  the  pulmonary 
artery  and  the  appendix  of  the  right  auricle.  It  then  turns  to  the 
right  in  the  groove  between  the  right  ventricle  and  auricle  to  the 
back  of  the  heart,  where  it  divides  into  two  branches;  one  of 
which  descends  in  the  posterior  inter-ventricular  furrow  towards 
the  apex  of  the  heart ;  the  other,  which  appears  to  be  the 
continuation  of  the  main  trunk,  runs  in  the  left  auriculo-ven- 
tricular groove.  Besides  these  branches,  the  right  coronary  gives 
off  a  large  branch  which  runs  along  the  free  border  of  the  right 
ventricle. 

Thus,  the  leading  trunks  of  the  coronary  arteries  run  in  the 
furrows  of  the  heart,  usually  surrounded  by  fat.  Their  numerous 
branches  supply  the  walls  of  the  auricles  and  ventricles,  and  their 
terminations  communicate  slightly  with  each  other. 

COEONABT  The  vein  which  corresponds  with  the  anterior 

VEINS  AND  SINUS,  coronary  artery  ascends  in  the  inter-ventricular 
sulcus,  and  then  curves  round  the  left  side  of  the  heart  in  the 
auriculo-ventricular  groove,  where  it  takes  the  name  of  the  great 
cardiac  vein.  This  vein  soon  dilates  into  a  large  trunk,  the 
coronary  sinus,  which  opens  into  the  back  of  the  right  auricle. 

M   2 


164 


DISSECTION    OF    THE    HEART. 


Other  veins,  known  as  the  posterior  cardiac,  three  or  four  in 
number,  ascend  along  the  posterior  surface  of  the  heart,  to  open 
by  valved  orifices  into  the  coronary  sinus ;  while  others,  the  anterior 
cardiac  veins,  are  seen  running  up  on  the  anterior  surface  of 
the  right  ventricle  to  terminate  directly  in  the  right  auricle. 
The  coronary  sinus  is  about  an  inch  in  length,  and  its  orifice 
in  the  right  auricle  is  guarded  by  a  valve  (valve  of  Thebesius}  to 
prevent  regurgitation  of  the  blood.  It  is  covered  and  more  or 
less  supported  in  its  course  by  muscular  fibres  passing  from  one 
auricle  to  the  other. 

FIG.  30. 


DIAGRAM    OF   THE    RELATIVE    POSITION    OF   THK   VALVES    OF    THE    HEART, 
SEEN    FROM    ABOVE. 

A  is  placed  on  the  triangular  interval  where  the  fibrous  skeleton  is  the  thickest. 


FIBROUS  ZONES 
OR  SKELETON  OF 
THE  HEART. 


What  may  be  termed  the  fibrous  skeleton  of 
the  heart,  consists  of  four  rings  which  surround, 
respectively,  the  four  orifices  at  its  base  :  namely, 
the  two  auriculo-ventricular,  the  aortic,  and  the  pulmonary.  These 
rings  give  attachment  by  their  external  circumference  to  the 
muscular  fibres  of  the  heart,  and  from  their  internal  circumference 
send  fibrous  prolongations  to  form  the  framework  of  the  several 
valves.  The  skeleton  is  strongest  just  in  the  triangular  interspace 


DISSECTION"    OP    THE    HEAET.  165 

between  the  aortic  and  the  two  auriculo-ventricular  orifices  (letter  A 
in  fig.  30).  In  some  animals,  as  in  the  ox  and  the  elephant,  there 
is  here  an  irregularly  triangular  bone,  known  as  the  '  os  cordis.' 

The  relative  position  of  these  rings  is  best  seen  by  removing 
the  auricles  and  the  great  vessels  at  the  base  of  the  heart — leaving 
the  several  valves,  and  looking  at  them  from  above,  as  shown  in 
the  diagram.  The  pulmonary  ring  is  on  the  highest  level,  and 
nearest  to  the  sternum  ;  below  it,  is  the  aortic  ring  lying  between 
and  in  front  of  the  auriculo-ventricular  rings,  which  are  on  the 
lowest  level. 

ATTACHMENT  OF  ^^e  n^rous  rings  at  the  arterial  orifices  present 
THE  LAKGE  AETE-  three  festoons  with  their  concavities  directed  up- 
RIES  TO  THE  wards.  These  give  attachment,  above,  to  the  middle 

coat  of  the  artery  ;  below,  to  the  muscular  fibres 
of  the  heart ;  and,  internally,  to  the  fibrous  tissue  of  the  valves. 
The  vessels  are  also  connected  to  the  heart  by  the  serous  layer  of 
the  pericardium,  and  by  a  continuation  of  the  lining  membrane  of 
the  ventricle. 

This  smooth  membrane  lining  the  cavities  of 

ENDOCABDIUM.  ««.•.. 

the  heart  resembles  the  visceral  layer  of  the  peri- 
cardium, and  is  continuous  with  the  lining  membrane  of  the 
blood-vessels.  It  may  be  easily  stripped  off,  and  is  thin  and 
semi-transparent,  thicker  in  the  left  than  in  the  right  cavities, 
thickest  of  all  in  the  left  auricle.  It  consists  of  three  layers : 
1,  a  layer  of  flattened  polygonal  cells,  resting  upon,  2,  some  elastic 
fibres  resembling  the  fenestrated  coat  of  an  artery,  and,  3,  a  thin 
layer  of  connective  tissue. 

ARRANGEMENT  The  muscular  fibres  of  the  heart  are  of  the 

OF  THE  MUSCULAR  striped  variety,  but  differ  from  ordinary  striped 
FIBRES  OF  THE  muscular  tissue,  in  being  smaller,  destitute  of  sarco- 
lemma,  branched,  nucleated,  and  involuntary.  The 
fibres  of  the  auricles  are  distinct  from  those  of  the  ventricles.  They 
consist  of  a  superficial  layer  common  to  both  cavities,  and  a  deeper 
layer  proper  to  each.  The  superficial  fibres  run  transversely 
across  the  auricles,  and  are  most  marked  on  the  anterior  surface ; 
some  pass  into  the  septum.  Of  the  deeper  fibres,  some  are  annu- 


166  DISSECTION   OP   THE   HEART. 

lar  and  surround  the  auricular  appendages  and  the  entrance  of 
the  great  veins,  upon  which  a  few  may  be  traced  for  a  short  dis- 
tance ;  others,  looped,  run  over  the  auricles,  and  are  attached  in 
front  and  behind  to  the  auriculo-ventricular  rings. 

ARRANGEMENT  Speaking  generally,  it  may  be  said  that  the 
OF  THE  MUSCULAR  right  and  left  ventricles  of  the  heart  are  two 
FIBRES  OF  THE  conical  muscular  sacs,  enclosed  in  a  third,  which 

UTRICLES.  no£  onjv  envei0pes  them,  but  is  reflected  into  the 

interior  of  both,  at  their  apices,  so  as  to  line  their  cavities.  All 
the  muscular  fibres  are  attached  by  one  end  to  the  fibrous  rings  of 
the  orifices,  and,  by  the  other  end,  after  a  more  or  less  spiral 
course,  they  reach  the  rings  again,  either  directly  or  through  the 
medium  of  the  chordae  tendinese  and  valves. 

Let  us  first  take  the  arrangement  of  the  superficial  fibres, 
those,  namely,  of  the  sac  which  envelopes  both  ventricles.  The 
fibres  covering  the  anterior  surface  of  the  heart  start  from  the 
right  auriculo-ventricular  and  pulmonary  rings,  and  run  more  or 
less  spirally  from  right  to  left  towards  the  apex  of  the  heart :  those 
covering  the  posterior  part  of  the  heart  start  from  the  auriculo- 
ventricular  rings,  and  run  more  or  less  spirally  from  left  to  right 
to  reach  the  apex.  At  the  apex  what  becomes  of  the  fibres  ?  They 
form  a  whorl,  are  reflected  upon  themselves,  and  enter  the  interior 
of  the  ventricles  so  as  to  form  their  innermost  muscular  lining — in 
other  words,  the  fleshy  columns  of  their  cavities. 

VEHTRICULAR  Each  sac  consists  of  muscular  fibres,  arranged 

SACS.  more  or  less  transversely,  which  arise  from  some 

part  of  the  ring,  run  round  the  ventricle,  and  are  fixed  to  another 
part  of  the  ring.  Thus  each  sac  forms  a  hollow  conical  barrel, 
open  at  both  ends ;  the  broad  end  representing  the  orifice  of  the 
ring,  the  narrow  end  representing  the  orifice  through  which  the 
fibres  of  the  common  sac  enter  the  ventricles.* 

THICKNESS  OF  The  average  thickness  of  the  right  auricle  is 

THE  CAVITIES.          about  one  line ;  that  of  the  left,  one  and  a  half. 

*  For  further  information  on  this  subject,  consult  Pettigrew,  'Philosoph.  Trans- 
actions,' 1861;  Dr.  Sibson,  'Medical  Anatomy,'  1869;  Winckler,  ' Miiller's  Archiv,' 
1865;  Quain's  '  Anatomy,'  vol.  ii.  p.  257,  1876. 


PECULIARITIES    OF    FCETAL    HEART. 


167 


The  average  thickness  of  the  right  ventricle  at  its  thickest 
part — i.e.  the  base — is  about  two  lines.  That  of  the  left  ventricle 
at  its  thickest  part — i.e.  the  middle^ — is  about  half  an  inch.  In 
the  female  the  average  is  less. 

FIG.  31. 


SUP"  v.  c 


FORAMEN  OVALE 


PLAC  ENTA 

SCHEME   OF    THE   FCETAL    CIRCULATION. 


PECULIARITIES  The  heart  of  the  foetus  differs  from  that  of  the 

i)F  FCETAL  HEART.     adult  in  the  following  points  : — 1 .  The  Eustachian 
valve  is  well  developed  in  order  to  guide  the  current  of  blood  from 


168  F(ETAL   CIRCULATION. 

the  vena  cava  inferior  into  the  foramen  ovale.  2.  The  foramen 
ovale  is  widely  open.  3.  The  right  and  left  pulmonary  arteries 
are  very  small  and  ill  developed,  so  as  to  admit  very  little  blood 
to  the  lungs.  4.  The  ductus  arteriosus  (from  the  pulmonary 
artery  to  the  aorta)  is  widely  open.  5.  The  right  and  left  ventricles 
are  of  equal  thickness  because  they  have  equal  work  to  perform. 

F(ETAL  CIRCULATION. 

CIRCULATION  OF  The  umbilical  vein  (fig.  31),  bringing  pure  blood 
THE  BLOOD  IN  THE  from  the  placenta,  enters  at  the  umbilicus,  and 
passes  to  the  under  surface  of  the  liver,  where  it 
sends  off  some  small  branches  to  the  left  lobe.  At  the  transverse 
fissure  it  divides  into  two  branches  :  one,  the  smaller,  termed  the 
ductus  venosus,  passes  straight  to  the  inferior  vena  cava ;  the 
other  or  right  division  joins  the  vena  portae,  and  after  ramifying  in 
the  liver,  returns  its  blood  through  the  hepatic  veins  into  the 
inferior  vena  cava.  From  the  inferior  vena  cava,  the  blood  enters  the 
right  auricle,  and  this  stream  (directed  by  the  Eustachian  valve) 
flows  through  the  foramen  ovale  into  the  left  auricle.  From  the 
left  auricle  it  runs  into  the  left  ventricle,  and  thence  through  the 
aorta  (only  a  small  quantity  passing  into  the  descending  thoracic 
aorta)  into  the  great  vessels  of  the  head  and  the  upper  limbs, 
which  are  thus  supplied  by  almost  pure  blood. 

From  the  head  and  the  upper  limbs,  the  blood  returns  (impure) 
through  the  superior  vena  cava  into  the  right  auricle,  and  flows 
into  the  right  ventricle.  From  the  right  ventricle  it  passes  through 
the  pulmonary  artery,  and  the  ductus  arteriosus,  into  the  end 
of  the  arch  of  the  aorta ;  only  a  very  small  quantity  of  it  goinp; 
to  the  lungs.  From  the  aorta,  part  of  the  blood  is  distribute-  '•• 
to  the  pelvis  and  lower  extremities ;  part  is  conveyed  through  the 
umbilical  arteries  to  the  placenta,  where  it  becomes  oxygenated. 

The  following  changes  take  place  in  the  circulation  after 
birth  :— 

1.  The  umbilical  vein  becomes  obliterated  from  the  second  to 
the  fifth  day  after  birth,  and  subsequently  forms  the  round  liga- 
ment of  the  liver. 


STRUCTURE    OF   THE    LUNGS.  169 

2.  The  ductus  venosus  also  becomes  closed  about  the  same 
period. 

3.  The  foramen  ovate  and  ductus  arteriosus  become  com- 
pletely closed  from  the  sixth  to  the  tenth  day. 

4.  The  pulmonary  arteries  enlarge  and  convey  venous  blood 
to  the  lungs.     These  organs  during  foetal  life  receive  only  a  small 
quantity  of  blood  from  these  arteries. 

5.  The  hypogastric  arteries  become  obliterated  on  the  fourth 
or  fifth  day  after  birth. 


STEUCTUKE  OF  THE  LUNGS. 

The  lungs  are  very  vascular  spongy  organs  in  which  the  blood 
is  .oxygenated  by  exposure  to  atmospheric  air.  Their  situation  and 
shape  have  been  briefly  described  (p.  140).  We  must  now  examine 
the  trachea,  the  common  air-passage  to  both  lungs,  and  then 
trace  this  tube  downwards  to  its  bifurcation  into  the  two  bronchi, 
which,  with  their  minute  subdivisions,  form  the  main  structure 
of  the  lungs. 

This  is  a  partly  membranous,  partly  cartila- 
ginous tube,  and  is  situated  in  the  middle  line. 
It  extends  from  the  cricoid  cartilage,  i.e.  opposite  the  upper 
border  of  the  sixth  cervical  vertebra,  to  the  third  dorsal  ver- 
tebra, where  it  divides  into  two  tubes,  the  right  and  left 
bronchus :  one  for  each  lung.  Its  length  is  from  four  to  four 
and  a  half  inches,  and  its  width  from  eight  to  ten  lines ;  but  these 
measurements  vary  according  to  the  age  of  the  patient  and  the 
capacity  of  the  lungs.  The  trachea  is  surrounded  by  a  quantity 
of  loose  connective  tissue,  so  as  to  allow  of  its  free  mobility.  It 
is  kept  permanently  open  by  a  series  of  incomplete  cartilaginous 
rings,  from  sixteen  to  twenty  in  number,  which  extend  round  the 
anterior  two-thirds  of  its  circumference.  These  rings  are  deficient 
at  the  posterior  part  of  the  tube,  where  it  is  completed  by  a  fibro- 
muscular  membrane.  This  deficiency  allows  the  trachea  to  enlarge 
or  diminish  its  calibre ;  and  for  this  purpose  the  membranous  part 


170  STEUCTUEE    OF   THE    LUNGS. 

of  the  tube  is  provided  with  unstriped  muscular  fibres  which  can 
approximate  the  ends  of  the  rings. 

The  relations  of  the  trachea  to  the  surrounding  parts  should 
be  considered,  first,  in  the  neck,  and  then  within  the  thorax. 

In  the  neck,  it  has  in  front  of  it  the  isthmus  of  the  thyroid 
body,  the  sterno-hyoid  and  sterno-thyroid  muscles,  the  middle 
thyroid  veins,  two  layers  of  the  deep  cervical  fascia,  the  arteria  thy- 
roidea  ima,  if  present,  and  (at  the  root  of  the  neck)  the  innomi- 
nate and  left  common  carotid  arteries.  Laterally,  it  is  in  relation 
with  the  lobes  of  the  thyroid  body,  the  common  carotid  arteries,  the 
recurrent  laryngeal  nerves,  and  the  inferior  thyroid  arteries. 
Behind  it,  is  the  oesophagus,  inclining  slightly  to  the  left. 

In  the  chest,  in  front  of  the  trachea  are  the  origins  of  the 
sterno-hyoid  and  thyroid  muscles,  the  left  brachio-cephalic  vein, 
the  first  parts  of  the  innominate  and  left  common  carotid  arteries, 
the  transverse  portion  of  the  arch  of  the  aorta,  and  the  deep  cardiac 
plexus.  On  the  right  side  are  the  pleura  and  right  pneumogastric 
nerve ;  on  the  left,  the  pleura,  the  left  carotid,  the  left  pneumo- 
gastric, cardiac,  and  recurrent  laryngeal  nerves. 

BRONCHI,  RIGHT         The  two  bronchi  differ  in  length,  direction,  and 
AND  LEFT.  diameter.     The  right   is    shorter   than  the   left, 

about  an  inch  long,  and  passes  more  horizontally  to  the  root  of  its 
lung,  on  a  level  with  the  fourth  dorsal  vertebra.  It  is  larger  in  all 
its  diameters  than  the  left ;  hence,  foreign  bodies  which  have  acci- 
dentally dropped  into  the  trachea  are  more  likely  to  be  carried 
into  the  right  bronchus  by  the  current  of  the  air.  The  left  is 
about  two  inches  in  length,  and,  descending  more  obliquely  to  its 
lung  than  the  right,  enters  it  on  a  level  with  the  fifth  dorsal 
vertebra. 

The  vena  azygos  major  arches  over  the  right  bronchus,  to 
terminate  in  the  superior  v.c.  The  left  bronchus  passes  under 
the  arch  of  the  aorta  in  front  of  the  CESophagus,  and  subsequently 
crosses  in  front  of  the  descending  aorta. 

The  cartilages  of  the  trachea  vary  in  number  from  sixteen  to 
twenty,  of  the  right  bronchus  from  six  to  eight,  and  of  the  left 
from  nine  to  twelve.  Those  of  the  trachea  form  about  two-thirds 


STRUCTUEE    OP    THE    LUNGS.  171 

of  a  circle,  somewhat  like  a  horseshoe  in  shape,  and  about  one-sixth 
of  an  inch  in  their  vertical  direction.  The  first  cartilage  is  the 
broadest,  and  that  at  the  bifurcation  of  the  trachea  is  shaped  like 
the  letter  V ;  its  angle  projects  into  the  centre  of  the  main  tube, 
and  its  sides  belong  one  to  each  bronchus. 

The  cartilages  are  connected,  and  covered  on  their  outer  and 
inner  surfaces  by  a  tough  membrane,  consisting  of  connective  and 
elastic  tissues.  This  membrane  is  attached  above  to  the  circum- 
ference of  the  cricoid  cartilage,  and  is  continued  through  the 
whole  extent  of  the  trachea  and  bronchial  tubes.  Posteriorly, 
where  the  cartilages  are  deficient  it  maintains  the  integrity  of  the 
tube.  In  this  tissue,  which  is  of  a  pale  reddish  colour,  is  a  layer 
of  unstriped  muscular  fibres,  arranged  in  a  transverse  and  a  longi- 
tudinal direction. 

MUSCUIAB  This  thin  stratum  of  unstriped  muscular  fibres 

TISSUE,  is  exposed  when  the  fibrous  membrane  and  tracheal 

glands  have  been  removed.  Some  of  the  fibres  extend  transversely 
between  the  posterior  free  ends  of  the  cartilages,  while  some  are 
arranged  in  longitudinal  bundles.  By  their  contraction  they 
approximate  the  ends  of  the  cartilages,  and  diminish  the  calibre 
of  the  trachea. 

This  is  chiefly  found  in  the  membranous  part  of 

ELASTIC  TISSUE.  .../.,  .  .,.,,. 

the  tube,  and  its  fibres  run  in  a  longitudinal  direc- 
tion. It  is  this  tissue  which  raises  the  mucous  membrane  into 
folds,  and  its  elasticity  admits  of  the  elongation  and  the  recoil  of 
the  tube. 

TKACHEAL  Between  the  fibrous  and  muscular  layers  of  the 

GLANDS.  trachea  are  a  number  of  small  mucous  glands, 

most  numerous  on  the  posterior  part  of  .the  tube.  They  are 
compound  racemose  glands,  lined  with  columnar  epithelium,  and 
in  health  their  secretion  is  clear,  and  just  sufficient  to  lubricate 
the  air-passages.  In  bronchitis  they  are  the  sources  of  the  abun- 
dant viscid  expectoration. 

Mucous  MEM-  The  mucous  membrane  lining  the  air-passages 

BEANE-  is  a  continuation  of  that  of  the  larynx.  Its  colour 

in  the  natural  state  is  nearly  white,  but  in  catarrhal  affections  it 


172  STEUCTUEE    OP   THE    LUNGS. 

becomes  bright  red,  in  consequence  of  the  accumulation  of  blood 
in  the  capillary  vessels.  It  is  continued  into  the  ultimate  air- 
cells,  where  it  becomes  thinner  and  more  transparent.  In  its 
deeper  layer  is  found  a  considerable  amount  of  elastic  tissue ;  in 
its  superficial  layer  a  quantity  of  lymphoid  tissue.  Its  surface  is 
lined  with  a  layer  of  columnar  ciliated  epithelial  cells.  The 
vibratile  movement  of  the  cilia  is  directed  in  such  a  way  as  to 
favour  the  expectoration  of  the  mucus.  The  ciliated  epithe- 
lium lining  the  mucous  membrane  ceases  at  the  commencement 
of  the  air-cells,  where  it  is  replaced  by  the  squamous  variety. 

At  the  root  of  the  lung  each  bronchus  divides  into  two  branches, 
an  upper  and  a  lower,  corresponding  to  the  lobes  of  the  lung ;  on 
the  right  side,  the  lower  branch  sends  a  small  division  to  the  third 
lobe  of  the  lung.  The  tubes  diverge  through  the  lung,  and  divide 
into  branches,  successively  smaller  and  smaller,  until  they  lead  to 
the  air-cells.  These  ramifications  do  not  communicate  with  each 
other ;  hence,  when  a  bronchial  tube  is  obstructed,  all  supply  of 
air  is  cut  off  from  those  cells  to  which  it  leads. 

The  several  tissues,  cartilaginous,  fibrous,  muscular,  mucous, 
and  glandular,  which  compose  the  air-passages,  are  not  present 
in  equal  proportions  throughout  all  their  ramifications,  but  each  is 
placed  in  greater  or  less  amount  where  it  is  required.  The  car- 
tilaginous rings  necessary  to  keep  the  larger  tubes  permanently 
open  become,  in  the  smaller  tubes,  fewer  and  less  regular  in  form. 
As  the  subdivisions  of  the  tubes  multiply,  the  cartilages  consist  of 
small  pieces  placed  here  and  there;  they  become  less  and  less 
firm,  and  finally  disappear  when  the  tube  is  reduced  to  one- 
fortieth  of  an  inch  in  diameter.  The  smallest  air-passages  are 
entirely  membranous,  being  formed  of  fibrous,  elastic,  and  muscular 
tissues. 

The  lungs  are  composed  of  cartilaginous  and 
THE  LUNGS.  &  /        .  6      . 

membranous  tubes,  of  which  the  successive  sub- 
divisions convey  the  air  into  closely-packed  minute  cells,  called 
the  air-vesicles ;  of  the  ramifications  of  the  pulmonary  artery  and 
veins ;  of  the  bronchial  vessels  concerned  in  their  nutrition ;  of 
lymphatics  and  nerves.  These  component  parts  are  united  by 


STRUCTURE    OF   THE    LUNGS.  173 

connective  tissue,  and  covered  externally  by  pleura.  The  part  at 
which  they  respectively  pass  in  and  out  is  called  the  root  of  the 
lung. 

The  lungs  are  the  lightest  organs  in  the  body,  and  float  in 
water.  When  entirely  deprived  of  air  they  sink.  This  is  observed 
in  certain  pathological  conditions ;  e.g.  when  one  lung  is  com- 
pressed by  effusion  into  the  chest,  or  rendered  solid  by  inflam- 
mation. 

CONTKACTIBI-  When  an  opening  is  made  into  the  chest,  the 

LITY  OF  THE  lung,  which  was  in  contact  with  the  ribs,  imme- 

NG>  diately  recedes  from  them,  and,  provided  there  be 

no  adhesions,  gradually  contracts.  If  the  lungs  be  artificially 
inflated,  either  in  or  out  of  the  chest,  we  observe  that  they 
spontaneously  expel  a  part  of  the  air.  This  disposition  to 
contract,  in  the  living  and  the  dead  lung,  is  due  to  the  elastic 
tissue  in  the  bronchial  tubes  and  the  air-cells ;  but  more  especially 
to  a  layer  of  delicate  elastic  tissue  on  the  surface  of  the  lung, 
which  has  been  described  by  some  anatomists  as  a  distinct  coat, 
under  the  name  of  the  second  or  inner  layer  of  the  pleura.* 

The  lungs  are  of  a  livid  red  or  violet  colour ; 
they  often  present  a  mixture  of  tints,  giving  them 
a  marble -like  appearance.  This  is  not  the  natural  colour  of  the 
organ,  since  it  is  produced  in  the  act  of  dying.  It  depends  upon 
the  stagnation  of  the  venous  blood,  which  the  right  ventricle  still 
propels  into  the  lungs,  though  respiration  is  failing.  The  tint 
varies  in  particular  situations  in  proportion  to  the  amount 
of  blood,  and  is  always  deepest  at  the  back  of  the  lung.  But 
the  colour  of  the  proper  tissue  of  the  lung  apart  from  the 
blood  which  it  contains  is  pale  and  light  grey.  This  colour  is 
seldom  seen  except  in  the  lungs  of  infants  who  have  never  breathed, 
or  after  death  from  profuse  haemorrhage. 

Upon  or  near  the  surface  of  the  lungs,  numerous  dark  spots 
are  observed,  which  do  not  depend  upon  the  blood,  since  they  are 
seen  in  the  palest  lungs.  They  vary  in  number  and  size,  and 

*  In  some  animals,  the  seal  especially,  the  elasticity  of  this  tissue  is  very  strongly 
marked. 


174  STRUCTURE   OP   THE    LUNGS. 

* 

increase  with  age.  The  source  of  these  discolourations  is  not 
exactly  known ;  but  they  are  probably  deposits  of  minute  particles 
of  carbonaceous  matter  which  have  been  inhaled  with  the  air. 

In  the  male  the  average  weight  of  the  right 
lung  is  24  oz.,  that  of  the  left,  21  oz. ;  in  the  female 
the  average  is  about  17  oz.  on  the  right,  and  15  oz.  on  the  left  side. 
The  total  capacity  of  the  lungs  in  an  adult  male  of  ordinary 
height  is  282  cubic  inches ;  and  the  amount  of  air  still  contained 
in  the  lungs  after  a  forced  expiration  has  been  estimated  at  57  cubic 
inches.    The  difference  between  these  volumes  indicates  the  amount 
of  air  which  can  be  inhaled,  from  the  deepest  expiration  to  the  fullest 
inspiration,  and  has  been  termed  the  vital  capacity  of  the  lungs.* 
LOBULES  OF  THE         The  surface  of  the  healthy  lung  is  marked  by 
LuNG-  faint  white  lines,  which  map  it  out  into  a  number 

of  angular  spaces  of  various  size.  These  spaces  indicate  the  lobules 
of  the  lung.  Each  lobule  is  a  lung  in  miniature.  Whoever 
understands  the  structure  of  a  single  lobule,  understands  the  struc- 
ture of  the  entire  lung.  The  lobules  are  connected  by  fine  areolar 
tissue,  called  interlobular,  which  is  everywhere  soft  and  elastic  to 
allow  the  free  expansion  of  the  organ.  The  cells  of  this  tissue 
have  no  communication  with  the  air-vesicles  unless  the  latter  be 
ruptured  by  excessive  straining,  and  then  this  intermediate  tissue 
becomes  inflated  with  air,  and  is  called  '  inter lobular  emphy- 
sema.' When  infiltrated  with  serum  it  constitutes  e  oedema '  of 
the  lung. 

Each  lobule  receives  a  small  bronchial  tube,  lobular  bronchial 
tube,  which  subdivides  into  smaller  branches.  Thus  reduced  in 
size,  the  walls  of  the  tubes  no  longer  present  traces  of  cartilaginous 
tissue,  but  are  composed  of  a  delicate  elastic  membrane  upon 
which  the  capillaries  ramify  in  a  very  minute  network.f  Each 
tube  finally  leads  into  an  irregular  passage,  lobular  passage,  from 
which  proceed  on  all  sides  numerous  dilatations :  these  are  the 

*  Hutchinson,  '  Med.  Ghir.  Trans.,'  vol.  xxix.  1846. 

t  In  phthisis  the  expectoration  contains  some  of  the  debris  of  this  elastic  frame- 
work of  the  air-vesicles;  it  can  be  seen  under  the  microscope,  and  is  a  test  of  the 
character  of  the  sputa. 


STEUCTUEE  OP    THE    LUNGS. 


175 


FIG.  32. 


air-cells  or  alveoli,  which  vary  from  ^  to  -^  of  an  inch  in 
diameter  (fig.  32).  The  air-cells  themselves  present  a  number 
of  shallow  depressions,  separated  by  somewhat  prominent  parti- 
tions, so  that  their  interior  has  a  honey- 
combed appearance,  as  shown  in  fig.  32. 
The  purpose  of  these  is  to  increase 
the  extent  of  surface  upon  which  the 
capillaries  may  ramify.  The  structure 
of  the  minute  air-cell  of  the  human 
lung  is  in  all  respects  similar  to  the 
large  respiratory  sac  of  the  reptile. 

The  structure  of  the  air-cells  differs 
in  some  important  features  from  that 
of  the  small  bronchial  tubes ;  the 
muscular  tissue  disappears,  the  elastic 
tissue  is  no  longer  arranged  in  bundles, 
but  becomes  frayed  out  and  inter- 
mingled with  the  connective  tissue, 
and  the  ciliated  epithelium  is  replaced  U™ATE  AIB-CELLS  OF  THE 

,  .1,  ,.  . , ,  (FROM  KOLLIXER).      MAGNIFIED 

by  a  single  layer  of  squamous  epithe-      TWENTY.FITE  TIMES. 

Hum. 

PULMONARY  The  branches  of  the  pulmonary  artery  subdivide 

VESSELS.  with  the  bronchial  tubes.   Their  ultimate  ramifica- 

tions spread  out  in  such  profusion  beneath  the  epithelium  of  the 
air-cells,  that  a  well-injected  lung  appears  a  mass  of  the  finest 
network  of  capillaries.  This  network  is  single  and  is  so  close  that 
the  interstices  are  even  narrower  than  the  vessels,  which  are  on  an 
average  about  30100  of  an  inch  in  diameter.  The  blood  and  air 
are  not  in  actual  contact.  Nothing,  however,  intervenes  but  the 
wall  of  the  cell  and  the  capillary  vessels,  which  are  such  delicate 
structures  that  they  oppose  no  obstacle  to  the  free  interchange  of 
gases  by  which  the  blood  is  purified.  This  purification  is  effected 
by  the  taking  in  of  oxygen,  and  the  elimination  of  carbonic  acid 
and  watery  vapour.  The  most  complete  purification  takes  place 
in  the  single  layer  of  capillaries  between  the  folds  of  membrane 
projecting  into  the  cell ;  for  in  this  situation  both  sides  of  these 


17(3  STRUCTURE    OF   THE    LUNGS. 

vessels  are  exposed  to  the  action  of  the  air.  The  blood,  circulating 
in  steady  streams  through  this  capillary  plexus,  returns  through 
the  pulmonary  veins.  These,  at  first  extremely  minute,  gradually 
coalesce  into  larger  and  larger  branches  which  anastomose  very 
freely,  and  accompany  the  arteries.  They  finally  emerge  from  the 
root  of  the  lung  by  two  large  trunks  which  carry  the  oxygenated 
blood  to  the  left  auricle  of  the  heart.  The  pulmonary  veins  are 
not  provided  with  valves. 

BRONCHIAL  These  are  small  arteries,  two  or  more  in  number 

AHTEBIES.  for  each  lung.     The  right  arises  either  from  the 

first  aortic  intercostal,  or,  conjointly  with  the  left  bronchial,  from 
the  thoracic  aorta.  The  left  comes  from  the  thoracic  aorta.  They 
enter  the  lung  behind  the  divisions  of  the  bronchi,  which  they 
accompany.  They  are  the  proper  nutritive  vessels  of  the  organ. 
The  bronchial  vessels  are  distributed  in  various  ways  :  some  of 
their  branches  supply  the  coats  of  the  air-passages,  the  large  blood- 
vessels and  the  lymphatic  glands  ;  others  the  interlobular  tissue  : 
a  few  reach  the  surface  of  the  lung,  and  ramify  beneath  the  pleura. 
The  right  bronchial  veins  terminate  in  the  vena  azygos ;  the  left, 
in  the  superior  intercostal  vein. 

The  nerves  of  the  lung  are  derived  from  the  pneumogastric  and 
the  sympathetic.  They  enter  with  the  bronchial  tubes,  forming  a 
plexus  in  front  and  behind  them,  anterior  and  posterior  pulmo- 
nary plexus,  in  which  are  found  minute  ganglia. 

The  lymphatics  of  the  lungs  commence  in  the  lymphatic 
capillaries  in  the  interlobular  tissue,  and  thence  pass  to  the  surface 
forming  a  network  which  communicates  with  the  subpleural 
lymphatic  plexus :  others  take  their  origin  in  the  mucous  mem- 
brane of  the  bronchial  tubes,  and  all  eventually  enter  the 
bronchial  glands.  Of  these,  the  larger  are  situated  about  the 
bronchi  near  the  root  of  the  lung,  particularly  under  the  bifurcation 
of  the  trachea. 


DISSECTION   OF    THE    PHARYNX.  177 

DISSECTION   OF   THE  PHAEYNX. 

To  obtain  a  view  of  the  pharynx,  cut  through 
the  trachea,  the  oesophagus  and  the  large  vessels  of 
the  neck,  and  then  separate  them  from  the  bodies  of  the  cervical 
vertebrae,  with  which  they  are  loosely  connected.  The  base  of  the 
skull  should  be  sawn  through  transversely  between  the  vertebral 
column  and  the  styloid  processes  of  the  temporal  bone,  so  as  to 
leave  the  pharynx  and  the  larynx  attached  to  the  anterior  half  of 
the  section.  Horsehair  should  then  be  introduced  through  the 
mouth  and  oesophagus  to  distend  the  walls  of  the  pharynx. 

PHAETNX:  GENE-  The  term  pharynx  is  applied  to  that  part  of  the 
HAL  DESCRIPTION.  alimentary  canal  which  receives  the  food  after  it 
has  been  masticated,  and  propels  it  downwards  into  the  oesophagus. 
It  is  a  funnel-shaped  muscular  bag,  about  four  and  a  half  inches 
in  length.  Its  broadest  portion  is  situated  opposite  the  os  hyoides. 
Its  upper  part  is  attached  to  the  basilar  process  of  the  occipital 
bone  and  the  petrous  portions  of  the  temporal  bones ;  thence  it 
extends  to  the  lower  border  of  the  cricoid  cartilage,  where  the 
continuation  of  it  takes  the  name  of  oesophagus.  The  bag  is 
connected,  in  front,  to  the  sides  of  the  posterior  nares,  the 
tongue,  the  hyoid  bone  and  the  larynx;  and,  behind,  to  the 
bodies  of  the  cervical  vertebrae  by  loose  connective  tissue  which 
never  contains  fat.  In  abscesses  at  the  back  of  the  pharynx, 
the  pus  is  seated  in  this  tissue.  Parallel  ivith,  and  close  to  its 
sides,  run  the  internal  carotid  arteries,  the  internal  jugular 
veins,  the  eighth,  ninth  and  sympathetic  nerves.  Its  dimensions 
are  not  equal  throughout.  Its  breadth  at  the  upper  part  is  equal 
to  that  of  the  posterior  openings  of  the  nose  ;  here  it  is  only 
required  to  convey  air :  but  it  becomes  much  wider  in  the  situa- 
tion where  it  transmits  the  food — that  is,  at  the  back  of  the  mouth ; 
thence  it  gradually  contracts  to  the  oesophagus.  The  pharynx 
therefore,  may  be  compared  to  a  funnel  communicating  in  front  by 
wide  apertures  with  the  nose,  the  mouth,  and  the  larynx  ;  while 
the  oesophagus  represents  the  tube  leading  from  its  lower  end. 


178  DISSECTION    OP    THE    PHARYNX. 

The  upper  part  of  the  funnel  forms  a  cul-de-sac  at  the  basilar 
process  of  the  occipital  bone.  At  this  part  there  is,  on  each  side, 
the  opening  of  a  narrow  canal,  called  the  Eustachian  tube,  through 
which  air  passes  to  the  tympanum  of  the  ear.* 

Before  the  muscles  of  the  pharynx  can  be  examined,  we  must 
remove  a  layer  of  thin  fascia,  termed  the  pharyngeal  fascia. 
It  is  the  layer  of  deep  cervical  fascia  behind  the  pharynx,  and 
must  not  be  confounded  with  the  proper  pharyngeal  aponeurosis, 
which  intervenes  between  its  muscular  and  mucous  walls. 

At  the  back  of  the  pharynx,  near  the  base  of  the  skull,  are  a 
few  lymphatic  glands.  They  sometimes  enlarge,  and  form  a  per- 
ceptible tumour  in  the  pharynx. 

In  removing  the  fascia  from  the  pharyngeal  muscles  notice 
that  a  number  of  veins  ramify  and  communicate  in  all  directions. 
They  constitute  the  pharyngeal  venous  plexus,  and  terminate  in 
the  internal  jugular  veins. 

CONSTRICTOR  They  are  three  in  number,  and  arranged  so  that 

MUSCLES  OF  THE  they  overlap  each  other — i.e.  the  inferior  overlaps 
PHARYNX.  tne  middle,  and  the  middle  the  superior  (fig.  33). 

They  have  the  same  attachments  on  both  sides  of  the  body  ;  and 
the  fibres  from  the  right  and  left  meet  together,  and  are  inserted 
in  the  mesial  line,  the  insertion  being  marked  by  a  white  longitu- 
dinal line  called  the  raphe. 

The  inferior  constrictor  arises  from  the  side  of  the  cricoid 
cartilage,  from  the  oblique  ridge  and  the  upper  and  lower  borders 
of  the  thyroid  cartilage.  Its  fibres  expand  over  the  lower  part 
of  the  pharynx.  The  superior  fibres  ascend ;  the  middle  run 

*  Observe  that  the  pharynx  conducts  to  the  oesophagus  by  a  gradual  contraction 
of  its  channel.  This  transition,  however,  is  in  some  cases  sufficiently  abrupt  to 
detain  a  foreign  body,  such  as  a  morsel  of  food  more  bulky  than  usual,  at  the  top 
of  the  oesophagus.  If  such  a  substance  become  firmly  impacted  in  this  situation, 
one  can  readily  understand  that  it  will  not  only  prevent  the  descent  of  food  into 
the  stomach,  but  that  it  may  occasion,  by  its  pressure  on  the  trachea,  alarming 
symptoms  of  suffocation.  Supposing  that  the  obstacle  can  neither  be  removed  by 
the  forceps,  nor  pushed  into  the  stomach  by  the  probang,  it  may  then  become 
necessary  to  extract  it  by  making  an  incision  into  the  oesophagus  on  the  left  side  of 
the  neck. 


DISSECTION   OF    THE    PHARYNX. 


179 


transversely ;  the  inferior  descend,  and  are  identified  with  the 
oesophagus.  Beneath  its  lower  border  the  recurrent  laryngeal 
nerve  enters  the  larynx.  Its  nervous  supply  is  from  the  pharyn- 
geal  plexus. 

FIG.  33. 


j\J       Tensor  palati. 

Levator  palati. 


Orbiciilaris  oris    .  _ 

Pterygo-maxill  ary 

ligament       .    . 


Mylo-hyoideus . 

Os  hyoides   .    .    . 
Thyro-hyoid    liga- 
ment   .     .     .     . 


Pom  urn  Adami 


Cricoid  cartilage     

Trachea  .    .    . 


Glosso-pharyngeal  n. 
Stylo-pharyngeus. 


Superior  laryngeal 
nerve  and  artery. 


External  laryngeal  u. 
Crico-thyroid. 

Inferior  laryngeal  n. 
(Esophagus. 


MUSCLES    OF    THE    PHARYNX. 


The  middle  constrictor  arises  from  the  upper  edge  of  the 
greater  cornu  of  the  os  hyoides,  from  its  lesser  cornu,  and  part  of 
the  stylo-hyoid  ligament.  Its  fibres  take  different  directions,  so 
that,  with  those  of  the  opposite  muscle,  they  form  a  lozenge.  The 


N    2 


180  DISSECTION    OF    THE    PHARYNX. 

lower  angle  of  the  lozenge  is  covered  by  the  inferior  constrictor  ; 
the  upper  angle  ascends  nearly  to  the  basilar  process  of  the  occi- 
pital bone,  and  terminates  upon  the  pharyngeal  aponeurosis. 
The  external  surface  of  the  muscle  is  covered  at  its  origin  by  the 
hyo-glossus.  Its  nerve  comes  from  the  pharyngeal  plexus. 

Between  the  middle  and  inferior  constrictors,  the  superior 
laryngeal  artery  and  nerve  perforate  the  thyro-hyoid  membrane  to 
supply  the  larynx. 

The  superior  constrictor  arises  from  the  hamular  process  of 
"the  sphenoid  bone,  and  from  the  lower  part  of  its  internal  ptery- 
goid  plate  ;  from  the  pterygo-maxillary  ligament  (which  connects 
it  with  the  buccinator)  ;  from  the  back  part  of  the  mylo-hyoid 
ridge  of  the  lower  jaw,  and  from  the  side  of  the  tongue.  The 
fibres  pass  backwards  to  the  mesial  line :  some  of  them  are  inserted 
through  the  medium  of  the  pharyngeal  aponeurosis  into  the  basilar 
process.  Its  nerve  comes  from  the  pharyngeal  plexus. 

The  upper  border  of  the  superior  constrictor  presents,  on  either 
side,  a  free  semilunar  edge  with  its  concavity  upwards,  so  that, 
between  it  and  the  base  of  the  skull,  a  space  is  left  in  which  the 
muscle  is  deficient  (fig.  33).  Here  the  pharynx  is  strengthened 
and  walled  in  by  its  own  aponeurosis.  The  space  is  called  the 
sinus  of  Morgagni ;  and  in  it,  with  a  little  dissection,  we  expose 
the  muscles  which  raise  and  tighten  the  soft  palate :  i.e.  the  levator 
palati,  and  the  tensor  palati.  The  Eustachian  tube  opens  into  the 
pharynx  just  here.  The  fibres  of  the  stylo-pharyngeus  pass  in 
between  the  superior  and  middle  constrictors,  and  expand  upon  the 
side  of  the  pharynx  ;  some  of  them  mingle  with  those  of  the  con- 
strictors so  as  to  be  able  to  lift  up  the  pharynx  in  deglutition ;  but 
most  of  them  are  inserted  into  the  superior  and  posterior  margins 
of  the  thyroid  cartilage. 

PHARYNGEAL  The  pharyngeal  aponeurosis  intervenes  between 

MEMBRANE  OR  the  muscles  and  the  mucous  membrane  of  the 
APONEUROSIS.  pharynx.  It  is  attached  to  the  basilar  process  of 

the  occipital  bone,  and  to  the  points  of  the  petrous  portions  of 
the  temporal  bones.  It  maintains  the  strength  and  integrity 
of  the  pharynx  at  its  upper  part,  where  the  muscular  fibres  are 


DISSECTION    OF    THE    PHARYNX. 


181 


deficient ;  but  it  gradually  diminishes  in  thickness  as  it  descends, 
and  is  finally  lost  on  the  oesophagus.      Notice   the  number   of 


Fto.  34. 


Eustachian  tube. 
Levator  palati  m. 


Tensor  palati  in. 
Hamular  process. 


Posterior  palatine  arch. 
Tonsil. 

—  Anterior  palatine  arch. 

Epiglottis. 
Aryteno-epiglottidean  fold. 

Opening  into  the  larynx. 


Opening  into  theresopliagus. 


DIAGRAMMATIC    VIEW    OF    THE   PHARTNX    LAID    OPEN   FHOM    BEHIND. 

mucous  glands  upon  this  aponeurosis,  especially  near  the  base  of 
the  skull  and  the  Eustachian  tube.  These  glands  sometimes 
enlarge  and  occasion  deafness  from  the  pressure  on  the  tube. 


182  DISSECTION    OF   THE    PHARYNX. 

OPENINGS  INTO  Lay  open  the  pharynx  by  a  longitudinal  incision, 
THE  PHARYNX.  and  observe  the  seven  openings  leading  into  it 
(fig.  34): — 1.  The  two  posterior  openings  of  the  nares.  2.  On 
either  side  of  them,  near  the  lower  turbinated  bones,  are  the 
openings  of  the  Eustachian  tubes :  below  the  nares  is  the  soft 
palate,  with  the  uvula.  3.  Below  the  soft  palate  is  the  communi- 
cation with  the  mouth,  called  the  isthmus  faucium.  On  either 
side  of  this  are  two  folds  of  mucous  membrane,  constituting  the 
anterior  and  posterior  half-arches  of  the  palate ;  between  them  are 
the  tonsils.  Below  the  isthmus  faucium  is  the  epiglottis,  which  is 
connected  to  the  base  of  the  tongue  by  three  folds  of  mucous 
membrane.  4.  Below  the  epiglottis  is  the  aperture  of  the  larynx. 
5.  Lastly,  is  the  opening  into  the  oesophagus.* 

Mucous  These  structures  are  lined  by  mucous  membrane 

MEMBRANE.  common  to  the    entire   tract  of  the    respiratory 

passages  and  the  alimentary  canal.  But  this  membrane  presents 
varieties  in  the  different  parts  of  these  channels,  according  as  they 
are  intended  as  passages  for  air  or  for  food.  The  mucous  membrane 
of  the  pharynx  above  the  velum  palati,  being  intended  to  transmit 
air  only,  is  very  delicate  in  its  texture,  and  lined  by  columnar 
ciliated  epithelium  like  the  rest  of  the  air-passages.  But  opposite 
the  fauces,  the  mucous  membrane  resembles  that  of  the  mouth,  and 
is  provided  with  squamous  epithelium.  At  the  back  of  the  larynx 
the  membrane  is  corrugated  into  folds,  to  allow  the  expansion  of  the 
pharynx  during  the  passage  of  the  food. 

The  membrane  is  lubricated  by  a  secretion  from  the  numerous 
mucous  glands  which  are  situated  in  the  submucous  tissue  through- 
out the  whole  extent  of  the  pharynx,  particularly  in  the  neighbour- 
hood of  the  Eustachian  tubes. 

POSTHRIOE  These  are  two  oval  openings,  each  of  which  is 

OPENINGS  OF  THE  about  an  inch  in  the  long,  and  half  an  inch  in  the 
NASAL  Fossa.  sllort  diameter.  They  ate  bounded  above  by  the 

*  On  reflecting  the  mucous  membrane  at  the  pharyngeal  termination  of  the 
Eustaclrian  tube,  a  thin  pale  muscle,  the  salpingo-pharyngeus,  can  be  made  out.  It 
arises  by  a  thin  tendon  from  the  Eustachian  tube,  and  joins  the  palato-pharyngeus. 
It  is  lost  among  the  fibres  of  the  constrictor  muscles. 


SOFT    PALATE.  183 

body  of  the  sphenoid  bone,  externally  by  its  pterygoid  plate,  below 
by  the  horizontal  portion  of  the  palate  bone ;  they  are  separated 
from  each  other  by  the  vomer. 

On  removing  the  mucous  membrane  from  the  posterior  part  of 
the  roof  of  the  nose  and  the  top  of  the  pharynx,  you  will  find 
beneath  it  much  fibrous  tissue.  Hence  polypi  growing  from  these 
'parts  are,  generally,  of  a  fibrous  nature. 

ISTHMUS  This  name  is  given  to  the  opening  by  which  the 

FAUCIUM.  mouth  communicates   with   the  pharynx.      It  is 

bounded,  above  by  the  soft  palate  and  uvula,  below  by  the  root  of 
the  tongue,  and  on  either  side  by  the  arches  of  the  palate,  enclosing 
the  tonsils  between  them. 

This  movable  prolongation  of  the  roof  of  the 
mouth  is  attached  to  the  border  of  the  hard 
palate,  and  laterally  to  the  side  of  the  pharynx.  Posteriorly  it  has 
a  free  edge,  and  a  pendulous  projection  in  the  centre,  called  the 
uvula.  It  constitutes  an  imperfect  partition  between  the  mouth 
and  the  posterior  nares.  Its  upper  or  nasal  surface  is  convex  and 
continuous  with  the  floor  of  the  nose ;  its  lower  surface  is  concave, 
in  adaptation  to  the  back  of  the  tongue,  and  is  marked  in  the 
middle  by  a  ridge  or  raphe,  indicating  its  original  formation  by 
two  lateral  halves.  The  soft  palate,  when  at  rest,  hangs  obliquely 
downwards  and  backwards ;  but  in  swallowing,  it  is  raised  to  the 
horizontal  position  by  the  levatores  palati,  comes  into  apposition 
with  the  back  of  the  pharynx,  and  thus  prevents  the  food  from 
passing  through  the  nose. 

On  making  a  perpendicular  section  through  the  soft  palate, 
you  see  that  the  great  bulk  of  it  is  made  up  of  muciparous  glands, 
which  lie  thick  on  its  under  surface  to  lubricate  the  passage  of 
the  food.  Above  these  glands  is  the  palato-glossus,  then  the 
aponeurosis  of  the  palate ;  still  higher,  are  the  two  portions  of  the 
palato-pharyngeus  (separated  by  the  fibres  of  the  levator  palati), 
the  azygos  uvulae,  and,  lastly,  the  nasal  mucous  membrane.  The 
soft  palate  is  supplied  with  blood  by  the  descending  palatine 
branch  of  the  internal  maxillary,  and  the  ascending  palatine  branch 
of  the  facial.  Its  nerves  are  derived  from  the  palatine  branches  of 


184  60FT    PALATE. 

the  second  (superior  maxillary)  division  of  the  fifth  and  from  the 
glosso-pharyngeal. 

The  uvula  projects  from  the  middle  of  the  soft 
palate,  and  gives  the  free  edge  of  it  the  appearance 
of  a  double  arch.  It  contains  a  number  of  muciparous  glands,  and 
a  small  muscle,  the  azygos  uvulce.  Its  length  varies  according 
to  the  state  of  its  muscle.  It  occasionally  becomes  permanently 
elongated,  and  causes  considerable  irritation,  a  tickle  in  the  throat, 
and  harassing  cough.  When  you  have  to  remove  a  portion  of  it, 
cut  off  only  the  redundant  mucous  membrane. 

ARCHES  OF  THE          The   soft  palate  is  connected  with  the  tongue 
PALATE.  an(j  pharynx  by  two  folds  of  mucous  membrane  on 

each  side,  enclosing  muscular  fibres.  These  are  the  anterior  and 
posterior  half-arches  or  pillars  of  the  palate.  The  anterior  arch 
describes  a  curve  from  the  base  of  the  uvula  to  the  side  of  the 
tongue.  It  is  well  seen  when  the  tongue  is  put  out.  The  poste- 
rior arch,  commencing  at  the  side  of  the  uvula,  curves  along  the 
free  margin  of  the  palate,  and  terminates  on  the  side  of  the 
pharynx.  The  posterior  arches,  when  the  tongue  is  depressed,  can 
be  seen  through  the  span  of  the  anterior.  The  pillars  of  each  side 
diverge  from  their  origin,  and  in  the  triangular  space  thus  formed 
is  situated  the  tonsil.  The  chief  use  of  the  arches  of  the  palate  is 
to  assist  in  deglutition.  The  anterior,  enclosing  the  palato-glossi 
muscles,  contract  so  as  to  prevent  the  food  from  coming  back 
into  the  mouth :  the  posterior,  enclosing  the  palato-pharyngei, 
contract  like  side  curtains,  and  co-operate  in  preventing  the  food 
from  passing  into  the  nose.  In  vomiting,  food  does  sometimes 
escape  through  the  nostrils,  but  one  cannot  wonder  at  this, 
considering  the  violence  with  which  it  is  driven  into  the 
pharynx. 

MUSCLES  OF  THE         The  muscles  of  the  soft  palate  lie  immediately 
SOFT  PALATE.  beneath    the    mucous    membrane.       There    are 

five  pairs — namely,  the  levatores  palatj,  the  circumflexi  or 
tensores  palati,  the  palato-glossi,  the  palato-pharyngei,  and  the 
azygos  uvulae.  This  last  pair  is.  sometimes  described  as  a  single 
muscle. 


SOFT    PALATE.  185 

IRYATOB  This  muscle  arises  from  the  apex  of  the  petrous 

PALATI.  portion  of  the  temporal  bone  and  from  the  under 

part  of  the  cartilage  of  the  Eustachian  tube.  Its  fibres  spread 
out,  and  are  inserted  along  the  upper  surface  of  the  soft  palate, 
meeting  those  of  its  fellow  in  the  middle  line  (fig.  34).  Its 
action  is  to  raise  the  soft  palate,  so  as  to  make  it  horizontal  in 
deglutition.  It  is  supplied  by  a  nerve  from  the  spheno-palatine 
ganglion. 

This  muscle  is  situated  between  the  internal 
pterygoid  m.  and  the  internal  pterygoid  plate  of 
the  sphenoid  bone.  It  arises  from  the  scaphoid  fossa  of  the 
sphenoid  bone,  and  from  the  outer  side  of  the  cartilage  of  the 
Eustachian  tube.  Thence  it  descends  perpendicularly,  ends 
in  a  tendon  which  turns  round  the  hamular  process,  and  expands 
into  a  broad  aponeurosis,  which  is  inserted  into  the  horizontal 
plate  of  the  palate  bone,  and  is  also  connected  to  its  fellow 
of  the  opposite  side.  It  gives  strength  to  the  soft  palate.  A 
synovial  membrane  facilitates  the  play  of  the  tendon  round  the 
hamular  process.  Its  action  is  to  draw  down  and  tighten  the  soft 
palate,  and,  owing  to  its  insertion  into  the  palate  bone,  also  to 
keep  the  Eustachian  tube  open.  Its  nerve  is  derived  from  the 
otic  ganglion,  and  enters  the  muscle  on  its  inner  aspect. 

AZTGOS  OR  This  consists  of  two  thin  bundles  of  muscular 

LETATOB  UVULJK.  fibres  situated  one  on  each  side  of  the  middle  line. 
It  arises  from  the  aponeurosis  of  the  palate  and  descends  along 
the  uvula  nearly  down  to  its  extremity.  It  receives  its  nerve  from 
the  spheno-palatine  ganglion. 

PALATO-GLOSSCS         These  muscles  are  contained  within  the  arches 
AND  PAIATO-  of  the  soft  palate.     The  palato-glossus,  within 

PHAKYNGEUS.  foe   anterior   arch,   proceeds    from   the   anterior 

surface  of  the  soft  palate  to  the  side  of  the  tongue,  and  is  lost  in 
the  stylo-glossus  muscle.  The  palato-pharyngeus,  within  the 
posterior  arch,  arises  from  the  posterior  border  of  the  soft  palate 
by  two  origins  separated  by  the  levator  palati.  As  it  descends  its 
fibres  spread  out  and,  passing  along  the  side  of  the  pharynx,  blend 
.with  the  fibres  of  the  inferior  constrictor  and  the  stylo-pharyngeus. 


186  TONSILS.       EUSTACHIAN    TUBE. 

Both  these  muscles  are  supplied  by  the  descending  palatine  branches 
of  the  spheno- palatine  ganglion. 

The  tonsils  are  situated  at  the  entrance  of  the 
fauces,  between  the  arches  of  the  soft  palate. 
Their  use  is  to  lubricate  the  fauces  during  tbe  passage  of  the  food. 
On  their  inner  surface  are  visible  from  twelve  to  fifteen  orifices 
leading  into  crypts  which  make  the  tonsil  appear  like  the  shell  of 
an  almond.  Hence,  as  well  as  from  their  oval  figure,  they  are 
called  the  amygdalce. 

These  openings  lead  into  small  follicles  in  the  substance  of  the 
tonsil,  lined  by  mucous  membrane.  Their  walls  are  thick,  and 
formed  by  a  layer  of  closed  cells  situated  in  the  submucous  tissue. 
The  fluid  secreted  by  these  cells  is  viscid  and  transparent,  in  the 
healthy  state :  but  it  is  apt  to  become  white  and  opaque  in  in- 
flammatory affections  of  the  tonsils,  and  occasionally  accumulates 
in  these  superficial  depressions,  giving  rise  to  the  deceptive  appear- 
ance of  a  small  ulcer,  or  even  a  slough  in  the  part. 

The  tonsil  lies  close  to  the  inner  side  of  the  internal  carotid 
artery.  It  is  only  separated  from  this  vessel  by  the  superior 
constrictor  and  the  aponeurosis  of  the  pharynx.  Therefore,  in 
removing  a  portion  of  the  tonsil,  or  in  opening  an  abscess  near  it, 
the  point  of  the  instrument  should  never  be  directed  outwards, 
but  inwards  towards  the  mesial  line.*  The  tonsil  is  supplied 
with  blood  by  the  tonsillar  and  palatine  branches  of  the  facial, 
and  by  the  descending  palatine  branch  of  the  internal  maxillary. 
Nerves  are  furnished  to  it  from  the  glosso-pharyngeal. 

EUSTACHIAN  This  canal  conveys  air  from  the  pharynx  to  the 

TuBE-  tympanum    of  the   ear.      Its    orifice   is    situated 

opposite  the  back  part  of  the  inferior  spongy  bone.  The  direc- 
tion of  the  tube  from  the  pharynx  is  upwards,  backwards,  and 
outwards ;  it  is  an  inch  and  a  half  long.  The  narrowest  part  is 
about  the  middle,  and  here  its  walls  are  in  contact.  Near  the 
tympanum  its  walls  are  osseous,  but  towards  the  pharynx  they  are 

*  Cases  are  related  by  Portal  and  B^clard,  in  which  the  carotid  artery  was 
punctured  in  opening  an  abscess  in  the  tonsil.  The  result  was  immediately  fatal 
haemorrhage. 


HARD    PALATE.  187* 

composed  of  fibro-cartilage  and  fibrous  membrane.  The  cartila- 
ginous end  projects  between  the  origins  of  the  levator  and  the 
tensor  palati,  and  gives  attachment  to  some  of  their  fibres.  It  is 
situated  at  the  base  of  the  skull,  in  the  furrow  between  the  petrous 
portion  of  the  temporal  and  the  great  wing  of  the  sphenoid  bone. 
It  adheres  closely  to  the  bony  furrow,  as  well  as  to  the  fibro- 
cartilage  filling  up  the  foramen  lacerum  medium.  The  orifice 
is  not  trumpet-shaped,  as  usually  described,  but  an  elliptical  slit 
about  half  an  inch  long  and  nearly  perpendicular.  The  fibro- 
cartilage  bounds  it  only  on  the  inner  and  the  upper  part  of  the 
circumference  ;  the  integrity  of  the  canal  below  is  maintained  by 
tough  fibrous  membrane. 

The  Eustachian  tube  is  lined  by  a  continuation  of  the  mucous 
membrane  of  the  pharynx,  and  covered  by  ciliated  epithelium. 
That  which  lines  the  cartilaginous  portion  of  the  tube  is  thick 
and  vascular,  and  gradually  becomes  thinner  towards  the  tympanum. 
Hence,  inflammatory  affections  of  the  throat  or  tonsils  are  liable 
to  be  attended  with  deafness,  from  temporary  obstruction  of  the 
tube. 

Mucous  glands  surround  the  orifice  of  the  tube,  and  are  similar 
in  nature  and  function  to  the  glands  beneath  the  mucous  mem- 
brane of  the  mouth,  the  palate,  and  the  pharynx. 

The  hard  palate,  formed  by  the  superior  maxil- 
HARD  PALATE 

lary  and  palate  bones,  is  a  resisting  surface  for  the 

tongue  in  tasting,  in  mastication,  in  deglutition,  and  in  the  arti- 
culation of  sounds.  The  tissue  covering  the  bones  is  thick  and 
close  in  texture,  and  firmly  united  to  the  asperities  on  the  bones. 
But  it  is  not  everywhere  of  equal  thickness.  Along  the  raphe  in 
the  mesial  line,  it  is  much  thinner  than  at  the  sides ;  for  this 
reason,  the  hard  palate  is  in  this  situation  more  prone  to  be  per- 
forated in  syphilitic  disease. 

A  thick  layer  of  glands  (glandulce  palatines]  is  arranged  in 
rows  on  either  side  of  the  hard  palate.  These  glands  become  more 
numerous  and  larger  towards  the  soft  palate.  Their  orifices  are 
visible  to  the  naked  eye.  The  mucous  membrane  has  a  very 
thick  epithelial  coat,  which  gives  the  white  colour  to  the  palate;. 


188  MECHANISM  OF  DEGLUTITION. 

The  descending  palatine  branch  of  the  internal  maxillary  artery, 
and  the  palatine  nerves  from  the  superior  maxillary,  may  be  traced 
along  each  side  of  the  roof  of  the  mouth.  The  ramifications  of 
these  arteries  and  nerves  supply  the  soft  as  well  as  the  hard 
palate. 

MECHANISM  OF  With  the  anatomy  of  the  parts  fresh  in  your 

DEGLUTITION.  mind,  consider  for  a  moment  the  mechanism  of 

deglutition.  The  food  duly  masticated,  is  collected  into  a  mass 
upon  the  back  of  the  tongue ;  the  lower  jaw  is  then  closed  to  give 
a  fixed  point  for  the  action  of  the  muscles  which  raise  the  os 
hyoides  and  larynx,  and  the  food  is  carried  back  into  the  pharynx 
by  the  pressure  of  the  tongue  against  the  palate,  at  the  same  time 
that  the  pharynx  is  elevated  and  expanded  to  receive  it  (by  the 
stylo-pharyngei  on  each  side).*  The  food,  having  reached  the 
pharynx,  is  prevented  from  ascending  into  the  nasal  passages  by 
the  approximation  of  the  posterior  palatine  arches,  and  the  eleva- 
tion of  the  soft  palate,  which  thus  forms  a  horizontal  temporary 
roof  to  the  pharynx ;  it  is  prevented  from  returning  into  the 
mouth  by  the  pressure  of  the  retracted  tongue,  and  the  contraction 
of  the  anterior  palatine  arches  :  it  cannot  enter  the  larynx,  because 
its  upper  opening  is  closed  and  protected  by  the  falling  of  the 
epiglottis :  f  consequently,  being  forcibly  compressed  by  the  con- 
strictors of  the  pharynx,  the  food  passes  into  the  oesophagus, 
through  which  it  is  conveyed  into  the  stomach  by  the  undulatory 
contraction  of  that  tube. 

The  food  passes  with  different  degrees  of  rapidity  through  the 
different  parts  of  its  course ;  but  most  rapidly  through  the  pharynx. 
The  necessity  of  this  is  obvious,  as  the  air-tube  must  be  closed 
while  the  food  passes  over  it,  and  the  closure  produces  a  temporary 
interruption  to  respiration.  The  progress  of  the  food  through  the 
oesophagus  is  slow  and  gradual. 

*  The  larynx  being  also  elevated  and  drawn  forward,  a  greater  space  is  thus  left 
between  it  and  the  vertebrae  for  the  distension  of  the  pharynx. 

t  This  falling  of  the  epiglottis  is  effected,  not  by  special  muscular  agency,  but  by 
the  simultaneous  elevation  of  the  larynx  and  the  retraction  of  the  tongue.  A  perpen- 
dicular section  through  all  the  parts  concerned  is  necessary  to  show  the  working  of 
this  mechanism, 


DISSECTION    OP   THE    LARYNX.  189 


DISSECTION   OF   THE  LAKYNX. 

SITUATION  AND  The  larynx  is  the  upper  part  of  the  air-passage, 

RELATIONS.  jn  which  vocalisation  takes  place.     It  is  a  com- 

plicated apparatus  consisting  of   numerous  cartilages  articulated 
together  to  form  an  open  tube. 

It  forms  a  prominence  in  the  middle  line  of  the  neck,  covered 
in  front  by  the  integument  and  cervical  fascia,  the  sterno-hyoid, 
sterno-thyroid,  and  thyro-hyoid  muscles  and  the  thyroid  body. 
It  has  the  great  vessels  of  the  neck  on  each  side.  Above,  it  is 
attached  to  the  hyoid  bone ;  below,  it  is  continuous  with  the 
trachea ;  behind  it,  is  the  pharynx,  into  which  it  opens. 

Before  commencing  the  dissection  of  the  larynx,  the  student 
should  make  himself  acquainted  with  the  cartilages  which  compose 
it,  and  the  ligaments  which  connect  them,  as  seen  in  a  dry  pre- 
paration. 

This  bone,  named  from  its  resemblance  to  the 
Greek  Upsilon,  is  situated  between  the  larynx  and 
the  tongue,  and  serves  for  the  attachment  of  the  muscles  of  the 
tongue.  It  may  be  felt  immediately  below,  and  one  inch  and  a 
half  behind,  the  symphysis  of  the  jaw.  It  consists  of  a  body,  two 
greater  and  two  lesser  cornua.  The  body  is  the  thick  central 
portion.  Its  anterior  surface  is  convex,  and  has  a  median  vertical 
ridge ;  on  each  side  of  which  are  depressions  for  the  attachments 
of  muscles;  its  posterior  surface  is  smooth,  concave,  and  corresponds 
to  the  epiglottis.  The  greater  cornua  (right  and  left)  project 
backwards  for  about  an  inch  and  a  half,  with  a  slight  inclination 
upwards,  and  terminate  in  blunt  ends  tipped  with  cartilage.  In 
young  subjects  they  are  connected  to  the  body  of  the  bone  by 
fibre-cartilage ;  this  in  process  of  years  becomes  ossified.  The 
lesser  cornua  are  connected,  one  on  each  side,  to  the  point  of 
junction  between  the  body  and  the  greater  cornua,  by  means  of  a 
little  joint  lined  with  synovial  membrane,  which  admits  of  free 
motion.  They  are  of  the  size  of  a  barley-corn,  and  give  attachment 
to  the  stylo-hyoid  ligaments. 


190  DISSECTION   OF   THE    LAEYNX. 

The  os  hyoides  is  connected  with  the  thyroid 
cartilage  by  several  ligaments,  which  contain  a 
quantity  of  elastic  tissue.  There  is  : — 1.  The  thyro-hyoid  mem- 
brane, which  proceeds  from  the  superior  border  of  the  thyroid 
cartilage  to  the  upper  and  posterior  part  of  the  hyoid  bone.  In 
front  of  this  membrane  there  is  a  bursa,  of  which  the  use  is  to 
facilitate  the  play  of  the  thyroid  cartilage  behind  the  os  hyoides. 
The  central  portion  is  stronger  than  the  lateral,  and  is  called  the 
anterior  thyro-hyoid  ligament.  Through  the  lateral  part  of  this 
membrane,  the  superior  laryngeal  nerve  and  artery  enter  the 
larynx.  2.  The  right  and  left  lateral  thyro-hyoid  ligaments 
extend  between  the  extremities  of  the  greater  cornua  of  the 
os  hyoides,  and  the  ascending  cornua  of  the"  thyroid  cartilage. 
They  often  contain  a  small  nodule  of  cartilage,  cartilago  triticea. 

CARTILAGES  OF  The  framework  of  the  larynx   is    composed  of 

THE  LABTNX.  nine  cartilages — viz.,  the  thyroid,  the  cricoid,  the 

two  arytenoid,  the  two  cornicula  laryngis,  the  two  cuneiform 
cartilages  and  the  epiglottis.  These  are  connected  by  joints  and 
elastic  ligaments,  so  that  they  can  be  moved  upon  each  other  by 
their  respective  muscles ;  the  object  of  this  motion  being  to  act 
upon  two  elastic  ligaments  called  the  vocal  cords,  upon  the  vibra- 
tion of  which  phonation  depends. 

THTEOID  CAR-  This  cartilage,  so  called  because  it  shields  the 

TILAGE-  mechanism    behind  it,*   consists  of    two   lateral 

halves,  alee,  united  at  an  acute  angle  in  front,  which  forms  the 
prominence  termed  the  pomum  Adami.  This  prominence  pre- 
sents a  notch  at  its  upper  part,  to  allow  it  to  play  behind  the 
os  hyoides  in  deglutition.  There  is  a  bursa  in  front  of  it.  Each 
ala  is  somewhat  quadrilateral  in  form,  and  presents  for  examina- 
tion two  surfaces  and  four  borders.  The  outer  surface  of  each  ala 
is  marked  by  an  oblique  line  passing  downwards  and  forwards  from 
the  upper  cornu,  which  gives  attachment  to  the  sterno-thyroid  and 
thyro-hyoid  muscles.  The  smooth  surface  behind  the  ridge,  gives 
attachment  to  the  inferior  constrictor.  The  inferior  border  is 
slightly  arched  in  the  middle,  and  on  either  side  presents  a  convex 

*  Qvpebs,  a  shield. 


DISSECTION    OF    THE    LARYNX.  191 

prominence,  which  gives  attachment  to  the  crico-thyroid  muscle. 
The  superior  border  is  nearly  horizontal.  The  posterior  border 
is  nearly  vertical,  and  gives  insertion  to  the  stylo-pharyngeus 
and  palato-pharyngeus  muscles.  This  border  terminates  above  and 
below  in  round  projections  called  the  upper  and  lower  cornua. 
The  upper  is  the  longer  ;  the  lower  articulates  with  the  side  of  the 
cricoid  cartilage. 

CRICOID  CAR-  This  cartilage,  named  from  its  resemblance  to 

TILAGE.  a  ring,*  is  situated  below  the  thyroid.     It  is  not 

of  equal  depth  all  round.  It  is  narrow  in  front,  where  it  may  be 
felt  about  one  quarter  of  an  inch  below  the  thyroid  ;  from  this 
part,  the  upper  border  gradually  rises,  so  that  posteriorly,  the 
ring  is  an  inch  in  vertical  depth,  and  occupies  part  of  the  interval 
left  between  the  alse  of  the  thyroid.  In  the  middle  of  this  broad 
posterior  surface  is  a  vertical  ridge,  on  either  side  of  which  observe 
a  superficial  excavation  for  the  origin  of  the  crico-arytenoidei 
postici :  to  the  lower  part  of  the  vertical  ridge  are  attached  some 
of  the  longitudinal  fibres  of  the  oesophagus.  On  its  upper 
part  are  two  oval  slightly  convex  surfaces  for  the  articulation  of 
the  arytenoid  cartilages.  In  front,  its  upper  border  presents  a 
broad  excavation  to  which  the  crico-thyroid  ligament  is  attached. 
On  its  outer  surface,  external  to  the  depression  for  the  crico- 
arytenoideus  posticus,  is  an  elevated  facet  which  articulates  with 
the  inferior  cornu  of  the  thyroid  cartilage.  In  front  of  this 
articular  surface  it  gives  attachment  to  the  inferior  constrictor  of 
the  pharynx.  The  lower  border  is  connected  by  elastic  membrane 
to  the  first  ring  of  the  trachea.  The  inner  surface  is  smooth,  and 
the  upper  border  is  elliptical ;  its  lower  being  nearly  circular. 

The  thyroid  cartilage  is  connected  to  the  cricoid 
by  a  membrane — the  crico-thyroid.  It  consists  of 
a  median  triangular  portion  composed  mainly  of  elastic  tissue,  with 
its  base  directed  upwards.  The  lateral  portions  are  thin  and 
membranous,  extending  as  far  backwards  as  the  articular  facets 
for  the  thyroid  cartilage,  and  are  intimately  connected  with  the 
inferior  vocal  cords.  Between  the  inferior  cornu  of  the  thyroid 

*  Kpi/cos,  a  ring. 


192  DISSECTION   OF    THE    LARYNX. 

cartilage  and  the  cricoid  there  is  a  distinct  joint,  having  a  synovial 
membrane,  and  strengthened  by  a  capsular  ligament.  The  articu- 
lation allows  of  a  movement  revolving  upon  its  own  axis,  and, 
consequently,  permits  the  approximation  of  the  two  cartilages. 

ARYTENOID  These  cartilages  are  situated,  one  on  each  side, 

CARTILAGES.  at  the  back  of  the  cricoid  cartilage.    In  the  recent 

state,  before  the  membranes  and  muscles  have  been  removed,  the 
space  between  them  resembles  the  lip  of  a  ewer  * ;  hence  their 
name.  Each  is  pyramidal,  with  the  apex  upwards,  and  is  about 
five  or  six  lines  in  height,  and  three  lines  in  diameter  at  its  base. 
The  posterior' surface  of  each  is  triangular  and  concave,  and  gives 
attachment  to  the  arytenoideus  muscle :  the  anterior  surface  is 
irregular  and  convex,  affording  attachment  to  the  thyro-arytenoi- 
deus,  and  to  the  superior  or  false  vocal  cord :  the  internal  surface, 
the  narrowest  and  nearly  flat,  faces  the  corresponding  surface  of 
the  opposite  cartilage,  and  is  covered  with  mucous  membrane. 
The  base  is  broad,  and  presents  a  smooth  somewhat  triangular 
surface  which  articulates  with  the  cricoid  cartilage  :  in  front  of  the 
base  is  the  pointed  anterior  angle,  which  gives  attachment  to  the 
true  vocal  cord,  and  contributes  to  form  part  of  the  boundary  of 
the  rima  glottidis :  at  the  outer  and  back  part  of  the  base  is  the 
external  angle,  into  which  certain  muscles  moving  the  cartilage 
are  inserted :  viz.  the  crico-arytenoideus  posticus  and  crico-aryte- 
noideus  lateralis.  The  base  is  articulated  with  the  cricoid  by  a 
joint  which  has  a  loose  capsular  ligament  and  a  synovial  mem- 
brane, permitting  motion  in  all  directions,  like  the  first  joint  of 
the  thumb.  The  apex  is  truncated  and  points  backwards  and 
inwards.  It  is  surmounted  by  a  cartilaginous  nodule,  called  the 
corniculum  laryngis. 

CUNEIFORM  These  cartilages,  sometimes  calleTl  the  cartilages 

CARTILAGKS.  of  Wrisberg,  are  conical  in  form,  and  somewhat 

curved,  with  their  broader  part  directed  upwards  and  forwards. 
They  are  contained  in  the  aryteno-epiglottidean  fold. 

This  piece  of  yellow  fibro-cartilage  is  situated  in 
the  middle  line,  and  projects  over  the  larynx  like 

*  Apvraiva,  &  ewer. 


DISSECTION   OF   THE    LARYNX.  193 

a  valve.  It  is  like  a  leaf  with  its  stalk  directed  downwards.  Its 
ordinary  position  is  perpendicular,  leaving  the  upper  opening  of 
the  larynx  free  for  respiration;  but  during  the  elevation  of  the 
larynx  in  deglutition  it  becomes  horizontal,  falls  downwards  and 
backwards  over  the  larynx,  and  prevents  the  entrance  of  food  into 
it.  This  descent  of  the  epiglottis  is  accomplished,  not  by  special 
muscular  agency,  but  by  the  simultaneous  elevation  of  the  larynx 
and  the  retraction  of  the  tongue.  Its  apex  or  lower  part  is  at- 
tached by  the  thyro-epiglottic  ligament  to  the  angle  of  the  thyroid 
cartilage;  it  is  also  connected  by  an  elastic  ligament,  hyo-epi- 
glottic,  to  the  os  hyoides.  Laterally  its  borders  are  rather  turned 
backwards,  and  to  them  are  attached  two  folds  of  mucous  mem- 
brane which  pass  to  the  arytenoid  cartilages,  called  the  aryteno- 
epiglottic  folds.  Its  anterior  surface  is  only  free  at  its  base, 
where  it  is  connected  with  the  base  of  the  tongue  by  the  three  glosso- 
epiglottic  folds.  Its  posterior  or  laryngeal  surface  is  concavo- 
convex  and  free,  and  looks  towards  the  larynx.  The  surface  of  the 
epiglottis  is  closely  invested  by  mucous  membrane ;  this  being  re- 
moved, the  yellow  cartilage  of  the  epiglottis  is  seen  pitted  and 
often  perforated  by  the  small  muciparous  glands. 

The  cartilages  of  the  larynx  resemble  those  of  the  ribs  in  struc- 
ture. In  the  young  they  are  dense  and  elastic,  but  some  have  a 
tendency  to  ossify  with  age.  In  very  old  subjects,  the  thyroid  and 
cricoid  cartilages  are  often  completely  ossified,  and  their  interior 
presents  an  areolar  tissue,  containing  oily  matter,  analogous  to  the 
spongy  texture  of  the  bones.  The  epiglottis,  cornicula  laryngis 
and  cuneiform  cartilages  are  rarely  ossified,  on  account  of  their, 
composition,  which  resembles  that  of  the  ear  and  the  nose. 

The  larynx  must  now  be  examined  in  its  perfect  condition. 
Mucous  MEM-  Except  on  the  true  vocal  cords  and  the  epiglottis, 

BRANB  OF  THE  the  mucous  membrane  of  the  larynx  presents  a 

LARYNX.  wrinkled  appearance,  and  is  loosely  connected  to  the 

subjacent  structures  by  an  abundance  of  fibre-cellular  tissue,  which 
admits  of  its  being  elevated  into  large  folds.  This  tissue  deserves 
notice  from  the  rapidity  with  which  it  becomes  the  seat  of  serous 
effusion  in  acute  inflammation  of  the  larynx,  and  thus  produces 

0 


194  DISSECTION    OF   THE    LARYNX. 

symptoms  of  suffocation.  From  the  root  of  the  tongue  to  the 
anterior  surface  of  the  epiglottis,  the  membrane  forms  three  folds, 
glosso-epiglottw,  one  median,  and  two  lateral,  containing  elastic 
tissue.  From  the  epiglottis,  to  which  it  is  intimately  adherent,  it 
is  continued  backwards  on  either  side  to  the  apices  of  the  ary- 
tenoid  cartilages,  forming  the  aryteno-epiglottic  folds  which  bound 
the  entrance  into  the  larynx.  In  the  natural  state  it  is  of  a  pale 
rose  colour,  and  covered  by  ciliated  epithelium  below  the  false 
vocal  cords,  above  these  by  squamous  epithelium.  ' 

The  mucous  membrane  of  the  larynx  is  remarkable  for  its 
acute  sensibility.  This  is  requisite  to  guard  the  upper  opening  of 
the  larynx  during  the  passage  of  the  food  over  it.  The  larynx  is 
closed  during  the  act  of  deglutition;  but  if,  during  this  process, 
anyone  attempt  to  speak  or  laugh,  the  epiglottis  is  raised,  and 
allows  the  food  to  pass,  as  it  is  termed,  the  wrong  way.  As  soon 
as  the  foreign  body  touches  the  mucous  membrane  of  the  larynx, 
a  spasmodic  fit  of  coughing  expels  it. 

The  sub-mucous  tissue  of  the  larynx  is  studded  with  mucous 
glands.  An  oblong  mass  of  them  lies  in  the  aryteno-epiglottic  fold, 
and  they  are  particularly  numerous  about  the  ventricles  of  thelarynx. 
The  surface  of  the  epiglottis  towards  the  tongue  is  abundantly  pro- 
vided with  them.  Their  ducts  pass  through  the  epiglottis,  and 
may  be  recognised  as  minute  openings  on  its  laryngeal  aspect. 

SUPERIOR  This  is  the  opening  through  which  the  larynx 

OPENING  OF  THE  communicates  with  the  pharynx.  Its  outline  is 
LARYNX.  triangular,  with  its  base  directed  forwards,  and  it 

slopes  from  before  backwards.  Anteriorly  it  is  bounded  by  the 
epiglottis,  laterally  by  the  aryteno-epiglottic  folds  and  cuneiform 
cartilages,  posteriorly  by  the  arytenoid  cartilages  and  the  corni- 
cula  laryngis.  The  apex  presents  the  funnel-shape  appearance 
from  which  the  arytenoid  cartilages  derive  their  name. 

INFERIOR  Look  down  into  the  larynx   and   observe  the 

OPENING  OF  THE  triangular  horizontal  opening  in  the  middle  line ; 
LARYNX,  OR  EIMA  this  is  the  rima  glottidis  or  glottis.  Its  apex  is 
GLOTTIDIS.  directed  forwards,  its  base  backwards.  The  an- 

terior two-thirds  of  this  opening  is  bounded  by  the  inferior  or  true 


DISSECTION    OF    THE    LARYNX.  195 

vocal  cords,  the  posterior  third  by  the  arytenoid  cartilages.  Above 
the  true  vocal  cords  are  situated  the  superior  or  false  vocal  cords. 
On  each  side  of  the  larynx,  between  the  true  and  false  vocal  cords, 
is  a  small  recess,  the  ventricle  of  the  larynx,  leading  into  a  pouch 
called  the  sacculus  laryngis,  which  ascends  for  a  short  distance 
and  terminates  in  a  cul-de-sac  by  the  side  of  the  thyroid  cartilage. 
In  the  middle  line  below  the  base  of  the  epiglottis  is  seen  a 
round  elevation  covered  with  mucous  membrane  of  a  bright  red 
colour :  this  is  termed  the  cushion  of  the  epiglottis.  The  length 
of  the  rima  glottidis  in  the  male  is  eleven  lines ;  its  width  at  rest 
from  three  to  four  lines ;  in  the  female  its  length  is  eight  lines, 
its  width  two  lines. 

STTPEBIOB  OR  These  are  the  prominent  crescentic  folds  which 

FALSE  VOCAL  form   the   upper    boundaries    of    the    ventricles. 

COEDS.  They  are  called  the  false  vocal  cords  because  they 

have  little  or  nothing  to  do  with  the  production  of  the  voice. 
They  are  composed  of  elastic  tissue,  like  the  true  vocal  cords;  but 
they  also  contain  fatty  tissue,  which  the  true  ones  do  not. 

INFERIOR  OB  These  two  cords,  composed  of  elastic  tissue,  and 

TBUE  VOCAL  covered  with  very  thin  and  closely  adherent  mu- 

CoBDS-  cous   membrane,    extend    horizontally   from    the 

angle  of  the  thyroid  cartilage-  to  Fio  g . 

the  base  of  each  of  the  arytenoid. 

They  diverge  as  they  pass  back-          //ii^\\ Thyroid  cartilage. 

wards ;  the  space  between  them  is  //  \\  Tmc  yocai  cord. 

called   the  rima  glottidis.     We 
shall  presently  see  that,    by  the 
muscles  which  act  upon  the  ary- 
tenoid cartilages,  these  cords  can        /I        V "^~  Arytenoid  cartilage' 
be    approximated    or    separated  (^J^ — ^~^  Elastic  ll«sment- 
from  each  other;  in  other  words, 
the  rima  glottidis  can  be  closed  SHAPE  OF  THE  GLOTTIS 

J-1     L     J  A*71_  £C      •          .LI  WHEN    AT    EZST- 

or    dilated.       When    sufficiently 

tightened,  and  brought  parallel  by  means  of  certain  muscles,  the 
cords  are  made  to  vibrate  by  the  current  of  the  expired  air,  and 
thus  is  produced  the  voice. 

o  2 


196  DISSECTION    OP   THE    LARYNX. 

In  the  adult  male  the  true  vocal  cords  measure  about  seven 
lines ;  in  the  female  about  five  lines.  In  boys  they  are  shorter ; 
hence  their  peculiar  voice.  At  puberty,  the  cords  lengthen, 
and  the  voice  breaks.  The  free  edges  of  the  true  vocal  cords 
are  thin  and  sharp,  and  look  somewhat  upwards;  this  may  be 
demonstrated  by  making  a  vertical  transverse  section  through 
them. 

The  glottis  admits  of  being  dilated,  contracted,  and  even  com- 
pletely closed  by  its  appropriate  muscles.  When  at  rest,  its  shape 
is  triangular,  as  shown  in  fig.  35,  where  the  arytenoid  cartilages 
are  cut  through  on  a  level  with  the  vocal  cords.  During  every  in- 
spiration, the  glottis  is  dilated  by  the  crico-arytenoidei  postici ;  it 
then  becomes  spear-shaped  (fig.  37).  During  expiration,  it  re- 
sumes its  triangular  shape :  and  this  return  to  a  state  of  rest  is 
effected,  not  by  muscular  agency,  but  by  two  elastic  ligaments 
shown  in  fig.  35,  which  draw  the  arytenoid  cartilages  together. 
Thus  then  the  glottis,  like  the  chest,  is  dilated  by  muscular 
tissue ;  like  the  chest,  also,  it  is  contracted  by  elastic  tissue.  In 
speaking  or  singing,  the  glottis  assumes  what  is  called  the  vocal- 
ising position  —  that  ;is,  the  opening  becomes  narrower  and  its 
edges  nearly  parallel. 

VENTRICLES  OF          These  are  the  hollows  between  the  upper  and 
THE  LARYNX.  lower  vocal  cords,  and  each  leads  to  a  small  pouch, 

the  sacculus  laryngis.  Each  ascends  for  about  half  an  inch  as 
high  as  the  upper  border  of  the  thyroid  cartilage,  which  bounds  it 
on  its  outer  side,  while  on  the  inner  side  is  the  upper  vocal  cord. 
It  contains  from  sixty  to  seven ty^muciparous  glands.  Over  its 
inner  and  upper  part  is  a  layer  of  muscular  tissue,  compressor 
sacculi  laryngis  of  Hilton,  which  connects  it  with  the  aryteno- 
epiglottic  fold. 

INTRINSIC  There  are  eleven  muscles  which  act  upon  the 

MUSCLES  OF  THH  larynx :  five  on  each  side  and  one  in  the  middle. 
LARYNX.  f^g  five  pairs  are — the  crico-thyroidei,  the  crico- 

arytenoidei  postici,  the  crico-arytenoidei  laterales,  the  thyro-ary- 
tenoidei,  and  the  aryteno-epiglottidei.  The  single  one  is  the 
arytenoideus. 


DISSECTION    OP    THE    LAKYNX. 


197 


M.  CHICO-  This   muscle  is  situated    on  the  front  of  the 

THTEOIDEUS.  larynx.     It  arises  from  the  side  of  the  cricoid 

cartilage,  ascends  obliquely  outwards,  and  is  inserted  into  the 
inferior  border  and  lower  cornu  of  the  thyroid.  Its  action  is  to 
tigthen  the  vocal  cords.  It  does  this  by  depressing  the  thyroid 
cartilage :  since  this  cartilage  cannot  be  depressed  without  length- 
ening these  cords,  as  shown  by  the  dotted  line,  fig.  36.  Its  nerve 
is  the  external  laryngeal  branch  of  the  superior  laryngeal.  Be- 
tween the  anterior  borders  of  the  two  muscles  is  seen  the  crico- 
thyroid  membrane,  which  is  divided  in  Laryngotomy. 

FIG.  36. 


Arytenoid  cartilage  . 
Crico-arytenoid  joint 

Crico-thyroid  joint   .  — 


Thyroid  cartilage. 


Thyroid  cartilage  depressed. 

True  vocal  cord. 

True  vocal  cord  stretched. 


Crico-thyroid  muscle. 
Cricoid  cartilage. 


DlAGBAM    SHOWING    THE   ACTION    OF   THE    CHICO-THYBOID    MUSCLE. 


M.  CEICO- 

AEYTENOIDEUS 
POSTICUS. 


This  muscle  arises  from  the  posterior  part  of 
the  cricoid  cartilage  r  its  fibres  converge  and 
pass  outwards  and  upwards,  to  be  inserted  into, 
the  outer  angle  of  the  arytenoid.  Its-  action  is  to  dilate  the 
glottis.  It  does  this  by  drawing  the  posterior  tubercle  of  the 
arytenoid  cartilage  towards  the  mesial  line,  and  therefore  the 
anterior  angle  (to  which  the  vocal  cord  is  attached)  from  the 
mesial  line  (fig.  37).  In  this  movement  the  arytenoid  cartilage 
rotates  as  upon  a  pivot,  and  acts  as  a  lever  of  the  first  order  ;  the 
fulcrum  or  ideal  pivot  being  intermediate  between  the  power 


198 


DISSECTION    OF    THE    LARYNX. 


and  the  weight.  This  muscle  dilates  the  glottis  at  each  inspira- 
tion. Its  nerve  comes  from  the  inferior  laryngeal. 

M.  AKYTE-  This  single  muscle  is  situated  immediately  at 

NOIDEUS.  the  back  of  the  arytenoid  cartiiages.  The  fibres 

pass  across  from  one  cartilage  to  the  other  running  in  a  transverse 
direction.  Action. — By  approximating  the  arytenoid  cartilages, 
they  assist  in  contracting  the  glottis.  It  is  supplied  by  the  inferior 
laryngeal  nerve. 

M.  ABYTENO-  This  muscle  ari-ses  from  the  outer  angle  of  the 

EPIGLOTTIDEUS.  arytenoid  cartilage  and,  crossing  its  fellow  like 

FIG.  37. 


Vocal  cord  .... 
Thyroid  cartilage  . 
Cricoid  cartilage .  . 


Arytenoid  cartilage .    . 

Elastic  ligament  (crico- 

arytenoid)    .    .    .    . 


Thyro-arytenoideu.0. 


Crico-arytenoideus  la- 
teralis. 


Ideal  pivot. 


Crico-arytenoideus  pos- 
ticus. 


GLOTTIS    DILATED.       MUSCLES    DILATING    IT    BEPBESENTED    WAVY. 


the  letter  X,  is  inserted,  partly  into  the  apex  of  the  opposite 
arytenoid  cartilage,  and  partly  into  the  aryteno-epiglottidean  fold. 
M.  Gmco-  To  expose  this  muscle,  cut  away  the  ala  of  the 

ABYTENOIDEU3  thyroid  cartilage.  It  arises  from  the  upper 
LATEKALIS.  border  of  the  side  of  the  cricoid  cartilage,  and  is 

inserted  into  the  external  angle  of  the  base  of  the  arytenoid  in 
front  of  the  erieo-arytenoideus  posticus.  Action. — By  drawing 
the  arytenoid  cartilages  inwards,  the  muscles  of  opposite  sides 
contract  the  glottis  (fig.  38).  Its  nerve  comes  from  the  inferior 
laryngeal. 


DISSECTION    OP    THE    LAETNX. 


199 


M.  THTKO-  This   muscle   arises   from   the    angle   of    the 

ABYTENOIDEUS.  thyroid  cartilage  and  the  crico-thyroid  membrane, 
runs  horizontally  backwards,  and  is  inserted  into  the  base  and 
anterior  border  of  the  arytenoid.  Its  fibres  run  parallel  with  the 
vocal  cord,  and  some  of  them  are  directly  inserted  into  it.  Its 
nerve  comes  from  the  inferior  laryngeal. 

This  muscle  relaxes  the  vocal  cord.  More  than  this,  it  puts 
the  lip  of  the  glottis  in  the  vocalising  position  ;  in  this  position, 
the  margins  of  the  glottis  are  parallel,  and  the  chink  is  reduced  to 
the  breadth  of  a  shilling. 

FIG.  38. 


Vocal  cord 


Arytenoid  cartilage 
Elastic  ligament . 


Thyro-arytenoideus. 


Crico-arytenoidens  la- 
teralis. 


Crico-arytenoideus  pos- 
ticus. 


GLOTTIS    CLOSED.       MUSCLES    CLOSING    IT    BKPEESENTED    WATT. 


The  following  table  shows  the  action  of  the  several  muscles 
which  act  upon  the  glottis : — 


Crico-thyroidei     . 
Thyro-arytenoidei        ; 

Crico-arytenoidei  postici 
Crico-arytenoidei  laterales 

Arytenoideus 
Aryteno-epiglottidei 


Stretch  the  vocal  cords. 

Relax  the  vocal  cords,  and  place  them  in  the 

vocalising  position. 
Dilate  the  glottis. 
Draw  together  the  arytenoid  \   ,         , 

cartilages  [   ,  ... 

glottis. 
Ditto        ditto        ditto         ) 

Contract  the  upper  opening  of  the  larynx. 


The  blood-vessels  of  the  larynx  are  derived  from  the  superior 


200  MSSECTION    OF   THE    LARYNX. 

and  inferior  thyroid  arteries.  The  laryngeal  branch  of  the 
superior  thyroid  passes  through  the  thyro-hyoid  membrane  with 
the  corresponding  nerve,  and  divides  into  branches,  which  supply 
the  muscles  and  the  mucous  membrane.  The  laryngeal  branches 
of  the  inferior  thyroid  ascend  behind  the  cricoid  cartilage.  A 
constant  little  artery  passes  through  the  crico-thyroid  mem- 
brane. - 

The  nerves  of  the  larynx  are  the  superior  and  inferior  (re- 
current) laryngeal  branches  of  the  pneumogastric. 

The  superior  laryngeal,  having  passed  through  the  thyro-hyoid 
membrane,  divides  into  branches,  distributed  to  the  mucous  mem- 
brane of  the  larynx.  Its  filaments  spread  out  in  various  direc- 
tions ;  some  to  the  anterior  and  posterior  surfaces  of  the  epiglottis, 
and  to  the  aryteno-epiglottidean  folds,  others  to  the  interior  of  the 
larynx  and  the  vocal  cords.  A  constant  filament  descends  behind 
the  ala  of  the  thyroid  cartilage,  and  communicates  with  the  inferior 
laryngeal.  Its  external  laryngeal  branch  supplies  the  crico-thyroid 
muscle. 

The  inferior  (or  recurrent)  laryngeal  nerve  enters  the  larynx 
beneath  the  inferior  constrictor,  and  ascends  behind  the  joint 
between  the  thyroid  and  cricoid  cartilages.  It  supplies  all  the 
intrinsic  muscles  of  the  larynx,  except  the  crico-thyroid.  If  the 
recurrent  nerve  be  divided,  or  in  any  way  injured,  the  muscles 
moving  the  glottis  become  paralysed,  but  its  sensibility  remains 
unimpaired.  When  the  nerve  is  compressed  by  a  tumour — for 
instance,  an  aneurysm  of  the  arch  of  the  aorta — the  voice  is 
changed  to  a  whisper,*  or  even  lost. 

DIFFERENCE  BE-         Until  the  approach  of  puberty,  there  is  no  great 

TM'EEN  THE  MALE      difference  in  the  relative  size  of  the  male  and 

AND  THE  FEMALE       female  larynx.      The  larynx  of  the  male,  within 

two  years  after  this  time,  becomes  nearly  doubled 

in  size  ;  that  of  the  female  grows,  but  to  a  less  extent. 

The  larynx  of  the  adult  male  is  in  all  proportions  about  one 
third  larger  than  that  of  the  adult  female. 

The  alse  of  the  thyroid  cartilage  form  a  more  acute  angle  in 
*  '  Medical  Gazette,'  Dec.  1843. 


DISSECTION   OP    THE    TONGUE.  201 

the  male ;    hence  the  greater  projection  of  the  '  pomum  Adami,' 
and  the  greater  length  of  the  vocal  cords,  in  the  male. 

i       ^1     f^  ^       3    •    •    j.\.    (Male    .         ,     7  lines. 

The  average  length  of  the  vocal  cords  is  in  the  J 

(Female          .     5  lines. 

The  average  length  of  the  glottis  is  in  the    .     J     a  e    '         '        . . 

{Female         .     8  lines. 

The  size  of  the  larynx  does  not  necessarily  follow  the  propor- 
tions of  the  general  stature ;  it  may  be  as  large  in  a  little  person 
as  in  a  tall  one:  this  corresponds  with  what  we  know  of  the 
voice. 

CEICO-THTKOID  This  joint  is  provided  with  a  capsule  and  synovial 
AETICULATION.  membrane.  There  are,  besides,  two  strong  liga- 
ments. Both  proceed  from  the  cornu  of  the  thyroid  cartilage ; 
the  one  upwards  and  backwards,  the  other  downwards  and  forwards 
to  the  cricoid.  Remember  that  the  only  kind  of  motion  permitted 
is  vertical :  and  that  this  motion  regulates  the  tension  of  the 
vocal  cords. 


DISSECTION   OF  THE  TONGUE. 

The  tongue  is  a  complex  muscular  organ,  subservient  to  taste, 
speech,  suction,  mastication,  and  deglutition.  Its  upper  surface 
is  convex  and  free,  as  is  also  its  anterior  part  or  tip  which  lies 
behind  the  lower  incisor  teeth ;  its  posterior  and  inferior  part  is 
connected  to  the  os  hyoides  by  the  hyo-glossi,  to  the  styloid  process 
of  the  temporal  bone  by  the  stylo-glossi,  and  to  the  symphysis  of 
the  lower  jaw  by  the  genio -hyo-glossi  muscles. 

Its  upper  surface,  or  dorsum,  is  convex,  and  slopes  on  all  sides 
from  the  centre  :  running  along  the  middle  is  a  median  groove — 
raphe — which  terminates  posteriorly  in  a  depression,  the  foramen 
ccecum,  into  which  open  several  mucous  glands. 

The  surface  of  the  tongue  is  covered  with  mucous  membrane, 
which  is  composed  of  structures  similar  to  those  of  the  skin 
generally :  that  is  to  say,  it  consists  of  a  '  cutis  vera,'  with  nume- 
rous elevations  called  papillae,  and  of  a  thick  layer  of  squamous 


202  DISSECTION    OP   THE    TONGUE. 

epithelium.    The  cutis  is  much  thinner  than  that  of  the  skin  of  the 
body,  and  affords  insertion  to  some  muscular  fibres  of  the  tongue. 

The  mucous  membrane  on  the  under  aspect  of  the  tongue  is 
smooth  and  comparatively  thin,  and,  in  the  middle  line  in  front, 
forms  a  fold — the  frcenum  linguce — which  connects  it  to  the 
mucous  membrane  of  the  floor  of  the  mouth.  Laterally  the 
mucous  membrane  is  reflected  from  the  under  part  of  the  tongue 
to  the  lower  jaw,  and  forms  the  floor  of  the  mouth. 

From  the  posterior  part  of  the  tongue  the  mucous  membrane 
passes  to  the  soft  palate  on  each  side,  forming  the  folds  termed  the 
anterior  palatine  arches,  which  enclose  the  palato-glossi ;  there  are 
also  three  folds  to  the  epiglottis,  termed  the  glosso-epiglottic :  two 
lateral  and  one  median,  the  latter  enclosing  a  layer  of  elastic  tissue, 
called  the  glosso-epiglottic  ligament.  This  ligament  raises  the 
epiglottis  when  the  tongue  is  protruded  from  the  mouth ;  hence  the 
rule  of  never  pulling  the  tongue  forwards  when  passing  a  tube 
into  the  oesophagus,  otherwise  the  tube  might  pass  into  the 
larynx. 

PAPILLA  OF  The    anterior    two-thirds    of    the    tongue    are 

THE  TONGUE.  studded  with  numerous  small  eminences,  called 

papillce ;  these,  according  to  their  size  and  form,  are  distinguished 
into  three  kinds — viz.  papillce  circumvallatce,  papillce  fungi- 
formce,  and  papillce  filiformce  (fig.  39). 

The  papillce  circumvallatce  vary  in  number  from  eight  to  twelve, 
and  are  arranged  at  the  back  of  the  tongue  in  two  rows,  which 
converge  like  the  branches  of  the  letter  V,  with  the  apex  backwards, 
towards  the  foramen  caecum.  Each  of  these  papillae  is  circular, 
from  the  -^th  to  -^th  of  an  inch  wide,  and  slightly  broader  above 
than  below.  Each  is  surrounded  by  a  circular  fossa,  which  itself 
is  bounded  by  an  elevated  ring.  The  papillae  are  covered  with  a 
thick  stratum  of  scaly  epithelium,  beneath  which  are  numerous 
secondary  papillae.  Buried  in  the  epithelium  on  the  side  (but  not 
on  the  upper  surface)  of  these  papillae,  numerous  flask-shaped 
bodies,  called  the  taste  buds,  have  been  discovered.  Their  bases 
rest  upon  the  deeper  structures,  and  their  apices  open  upon  the 
surface.  According  to  recent  authorities  they  are  in  close  con- 


DISSECTION    OF    THE    TONGUE. 


203 


nection  with  the  ultimate  distribution  of  the  glosso-pharyngeal 
nerve.* 

The  papilla;  fungiformce,  smaller  and  more  numerous  than 
the  drcumvallatce,  are  scattered  chiefly  over  the  sides  and  tip  of 
the  tongue,  and  sparingly  over  its  upper  FIG.  39. 

surface.  They  vary  in  shape,  some  being 
cylindrical,  others  having  rounded  heads  like 
mushrooms;  whence  their  name.  Near  the 
apex  of  the  tongue  they  may  be  distin- 
guished during  life  from  the  other  papillae 
by  their  redder  colour.  In  scarlatina,  and 
some  exanthematous  fevers,  these  papillae 
become  elongated,  and  of  a  bright  red  colour : 
as  the  fever  subsides,  their  points  acquire  a 
brownish  tint;  giving  rise  to  what  is  called 
the  strawberry  tongue. 

The  papillce  filiformce  are  the  smallest 
and  most  numerous.  They  are  so  closely 
aggregated  that  they  give  the  tongue  a 
velvet-like  appearance.  Their  points  are 
directed  backwards,  so  that  the  tongue  feels 


UPPER     SURFACE     OF    THE 


smooth  if  the  finger  be  passed  over  it  from  TONGUE'  WITH  THE  FAUCES 

AND  TONSILS. 


1.  Papillae  circumvallataa. 

2.  Papillae  fungiformae. 


apex  to  base,  but  rough  if  in  the  contrary 

direction.     These   papillae  consist  of  small 

conical  processes  arranged  for  the  most  part  in  a  series  of  lines 

running  parallel  to  the  two  rows  of  the  papillae  circumvallatae. 

Each  papilla  is  covered  with  a  thick  layer  of  epithelium,  which  is 

prolonged  into  a  number  of  free  hairlike  processes. 

If  the  papillae  be  injected,  and  examined  under  the  microscope, 
it  is  found  that  they  are  not  simple  elevations,  like  those  of  the 
skin,  but  that  from  them  arise  secondary  papillae.  The  papillae 
circumvallatae  consist  of  an  aggregation  of  smaller  papillae  arranged 
parallel  to  each  other ;  and  the  papillae  fungiformae  consist  of  cen- 
tral stems  from  which  minute  secondary  papillae  shoot  off.  This 

*  For  further  information  about  these  bodies  the  student  is  referred  to  Engelman- 
Stracker's  '  Handbook.' 


204  DISSECTION    OF   THE    TONGUE. 

elaborate  structure  escapes  observation  because  it  is  buried  beneath 
the  epithelium.*  Each  secondary  papilla  receives  a  blood-vessel, 
which  passes  nearly  to  its  apex,  and  returns  in  a  loop-like  manner. 

The  papillae  are  covered  with  one  or  more  layers  of  squamous 
epithelium.  That  which  covers  the  filiform  is  superimposed  so 
thickly  as  to  give  it  sometimes  the  appearance  of  a  brush  when 
seen  under  the  microscope.  The  various  kinds  of  fur  on  the 
tongue  consist  of  thick  and  sodden  epithelium. 

Respecting  the  use  of  the  papillae,  it  i&  probable  that  they 
enable  the  tongue  to  detect  impressions  with  greater  delicacy. 
From  the  density  and  arrangement  of  their  epithelial  coat,  the 
filiform  papillae  give  the  surface  of  the  tongue  a  roughness,  which 
is  useful  in  its  action  upon  the  food.  An  apparatus  of  this  kind, 
proportionately  stronger  and  more  developed,  makes  the  tongue  of 
ruminant  animals  an  instrument  by  which  they  lay  hold  of  their 
food.  In  the  feline  tribe — e.g.  the  lion  and  tiger — these  papillae 
are  so  sharp  and  strong  that  they  act  like  rasps,  and  enable  the 
animal  to  lick  the  periosteum  from  the  bones  by  a  single  stroke  of 
his  tongue.  In  some  mammalia,  they  act  like  combs  for  cleaning 
the  skin  and  the  hair. 

Numerous  small  racemose  glands  are  found  in 
the  submucous  tissue  at  the  root  of  the  tongue. 
They  are  similar  in  structure  and  secretion  to  the  tonsillar  and 
palatine  glands,  so  that  there  is  a  complete  ring  of  glands  round 
the  isthmus  faucium.  Small  round  orifices  upon  their  surface 
indicate  the  termination  of  their  ducts.  Other  mucous  glands, 
with  ducts  from  one  quarter  to  half  an  inch  long,  are  situated  in 
the  muscular  substance  of  the  tongue. 

GLANDS  BE-  On  the  under  surface  of  the  apex  of  the  tongue 

NEATH  THE  APEX  is  placed,  on  either  side,  a  group  of  glands  pre- 
OF  THE  TONGUE.  sumed  to  be  salivary.  Considering  each  group  as 
one  gland,  observe  that  it  is  oblong,  with  the  long  diameter  from 
seven  to  ten  lines,  parallel  with  the  axis  of  the  tongue.  It  lies 
near  the  mesial  line,  a  little  below  the  ranine  artery,  on  the  outer 
side  of  the  branches  of  the  gustatory  nerve,  under  some  of  the 
*  See  Bowman  and  Todd's  '  Physiological  Anatomy.' 


DISSECTION   OP   THE    TONGUE.  205 

fibres  of  the  stylo-glossus.  Four  or  five  ducts  proceed  from  each 
group,  and  terminate  by  separate  orifices  on  the  under  surface  of 
the  tongue. 

MUSCULAR  The   substance  of  the  torrgue  is  composed  of 

FIBRES  OF  THE  muscular  fibres  and  of  a  small  quantity  of  fat. 
TONGUE.  "j^g  extrinsic  muscles  of  the  tongue  have  been 

described  in  the  dissection  of  the  submaxillary  region  (p.  47). 
We  have  now  to  examine  its  intrinsic  muscles.  For  this  purpose 
the  mucous  membrane  must  be  removed  from  the  dorsum  of  the 
tongue.  On  dissection  it  will  be  found  that  the  great  bulk  of  the 
organ  consists  of  fibres  which  proceed  in  a  longitudinal  direction, 
constituting  the  linguales  muscles. 

The  superior  lingualis  runs  longitudinally  beneath  the  mucous 
membrane  of  the  dorsum;  its  fibres  are  attached  posteriorly  to 
the  hyoid  bone  and  run    forwards  to  the  front   and   margin  of 
the  tongue.     Posteriorly  the  muscle  is  thin  and  is  covered  by  the 
fibres  of  the  palato-glossus  and  hyo-glossus. 

The  inferior  lingualis  is  larger  than  the  preceding,  and  is 
situated  on  the  under  aspect  of  the  tongue  between  the  genio-hyo- 
glossus  and  the  hyo-glossus.  It  may  be  readily  exposed  by  dis- 
secting the  under  surface  of  the  tongue  immediately  on  the  outer 
aspect  of  the  genio-hyo-glossus.  It  arises  posteriorly  from  the 
hyoid  bone  and  the  substance  of  the  tongue,  and  its  fibres  pass 
forwards  to  the  tip  of  the  tongue  after  being  reinforced  by  fibres 
from  the  stylo-glossus. 

The  transverse  fibres  form  a  considerable  part  of  the  thickness 
of  the  tongue  and  arise  from  the  fibrous  septum.  They  pass  out- 
wards between  the  superior  and  inferior  linguales,  ascending  as 
they  near  the  sides  of  the  tongue  where  the  fibres  become  con- 
tinuous with  those  of  the  palato-glossus.  A  considerable  amount 
of  fat  is  found  among  these  fibres. 

The  vertical  fibres  run  in  a  curved  direction,  descending  from 
the  dorsum  to  the  under  aspect  of  the  tongue,  with  the  concavity 
outwards.  They  interlace  with  the  transverse  fibres  and  with  the 
genio-hyo-glossus . 

On  tracing  the  genio-hyo-glossi  into  the  tongue,  we  find  that 


206  DISSECTION   OP   THE    ORBIT. 

some  of  their  fibres  ascend  directly  to  the  surface;  others  cross 
in  the  middle  line,  intersect  the  longitudinal  fibres  and  finally  ter- 
minate upon  the  sides  of  the  tongue.  Lastly,  the  fibres  of  the 
stylo-glossi  should  be  traced  along  the  side  of  the  tongue  to  the 
apex. 

FIBROUS  SEPTUM  The  fibrous  septum  of  the  tongue  is  a  vertical 
OF  THE  TONGUE.  plane  of  fibrous  tissue  which  extends,  in  the 
mesial  line,  from  the  base  to  the  apex.  It  is  connected  behind  with 
the  hyoid  bone,  and  lost  in  front  between  the  muscles.  In  it  is  some- 
times found  a  piece  of  fibro- cartilage,  called  nucleus  fibrosus 
linguae,  a  representative  of  the  lingual  bone  in  some  of  the  lower 
animals. 

The  arteries  supplying  the  tongue  are  the  dorsal  and  ranine 
branches  of  the  lingual  artery  (p.  52). 

The  nerves  to  the  tongue  should  now  be  followed  to  their 
termination.  The  hypoglossal  supplies  with  motor  power  all  the 
muscles.  The  gustatory  or  lingual  branch  of  the  inferior  division 
of  the  fifth  is  distributed  to  the  mucous  membrane  and  papillae  of 
the  apex  and  sides  of  the  tongue,  supplying  the  anterior  two- 
thirds  with  common  sensation.  Upon  this  nerve  depends  the 
sensation  of  all  ordinary  impressions,  such  as  that  of  hardness, 
softness,  heat,  cold,  and  the  like. 

The  glosso-pharyngeal  nerve  supplies  the  mucous  membrane 
at  the  back  and  the  sides  of  the  tongue,  and  the  papilte  circum- 
vallatse.  Under  the  microscope  small  ganglia  may  be  distinguished 
on  the  terminal  fibres  of  this  nerve. 


DISSECTION  OF  THE  OKBIT. 

To  expose  the  contents  of  the  orbit,  remove  that  portion  of  the 
orbital  plate  which  forms  the  roof  of  the  orbit  as  far  back  as  the 
optic  foramen,  making  one  section  on  the  outer  side,  the  other  on 
the  inner  side  of  the  roof.  In  doing  this,  be  careful  not  to  injure 
the  little  pulley  on  the  inner  side  for  the  superior  oblique.  The 
anterior  fourth  of  the  roof  should  be  turned  forwards  and  downwards, 


DISSECTION    OF    THE    ORBIT. 


207 


the  remainder  removed  by  bone  forceps.  The  eyeball  should  be 
made  tense  by  blowing  air  through  a  blow-pipe,  passed  well  into 
the  globe  through  the  end  of  the  optic  nerve. 

PEEIOSTEUM  OF          The  roof  being  removed,  we  expose  the  fibrous 
THE  ORBIT.  membrane,  which  lines  the  walls  of  the  orbit.     It 

is  a  continuation  of  the  dura  mater  through  the  sphenoidal  fissure. 
Traced  forwards,  we  find  that  at  the  margin  of  the  orbit  it  divides 
into  two  layers,  one  of  which  is  continuous  with  the  periosteum  of 
the  forehead,  the  other  forms  the  broad  tarsal  ligament  which  fixes 
the  tarsal  cartilage. 

FIG.  40. 


DIAGRAM    OF    THE    NERVES    OF    THE    ORBIT. 


FASCIA  OF  The  fascia  of  the  orbit  serves  the  same  purpose 

THE  ORBIT.  that  fascia  does  in  other  parts.     It  provides  the 

lachrymal  gland,  and  each  of  the  muscles,  with  a  loose  sheath, 
thin  and  delicate  at  the  back  of  the  orbit,  but  stronger  near  the 
eye,  where  it  passes  from  one  rectus  muscle  to  the  other,  so  that 
their  tendinous  insertions  into  the  globe  are  connected  by  it.  From 
the  insertion  of  the  muscles  it  is  reflected  backwards  over  the  globe 
of  the  eye,  and  the  optic  nerve,  and  separates  the  eye  from  the  fat 
at  the  bottom  of  the  orbit. 


208  DISSECTION   OP   THE    CEBIT. 

CONTENTS  OF  There  are  six  muscles  to  move  the  eye  ;  four  of 

THE  OBBIT.  which,  running  in  a  straight  direction,  are  called 

the  recti,  and  are  arranged  one  above,  one  below,  and  one  on 
each  side  of  the  globe.  The  remaining  two  are  called,  from  their 
direction,  obliqui,  one  superior,  the  other  inferior.  There  is  also 
a  muscle  to  raise  the  upper  eyelid,  termed  levator  palpebrce.  The 
nerves  are :  the  optic,  which  passes  through  the  optic  foramen ; 
the  third,  the  fourth,  the  first  division  of  the  fifth,  and  the  -sixth, 
all  of  which  pass  through  the  sphenoidal  fissure.  The  third 
supplies  all  the  muscles  with  motor  power,  except  the  superior 
oblique,  which  is  supplied  by  the  fourth,  and  the  external  rectus, 
which  is  supplied  by  the  sixth.  The  first  or  ophthalmic  division 
of  the  fifth  divides  into  a  frontal,  lachrymal,  and  nasal  branch. 
The  orbit  contains,  also,  a  quantity  of  fat,  which  forms  a  soft 
bed  for  the  eye  and  prevents  it  from  being  retracted  too  far  by 
its  muscles.  Upon  the  quantity  of  this  fat  depends,  in  some 
measure,  the  prominence  of  the  eyes.  Its  absorption  in  disease 
or  old  age  occasions  the  sinking  of  the  eyeballs.  The  eye  is 
separated  from  the  fat  by  a  fold  of  the  orbital  fascia,  which,  like 
a  tunica  vaginalis,  enables  the  globe  to  move  with  rapidity  and 
precision.  Lastly,  the  orbit  contains  the  lachrymal  gland. 

After  the  removal  of  the  periosteum  and  the  fascia  of  the  orbit, 
the  following  objects  should  be  carefully  traced.  In  the  middle 
are  seen  the  frontal  nerve  and  artery,  lying  upon  the,  levator 
palpebrse ;  on  the  inner  side  is  the  fourth  nerve  lying  on  and 
supplying  the  superior  oblique ;  on  the  outer  side,  the  lachrymal 
nerve  and  artery  pass  forwards  to  the  lachrymal  gland,  which  lies 
under  cover  of  the  external  angular  process. 

The  ophthalmic  or  first  division,  of  the  fifth  nerve,  after  giving 
off  from  its  inner  side,  while  within  the  cavernous  sinus,  the  nasal 
nerve,  divides  into  the  lachrymal  and  frontal  nerves,  of  which  the 
FRONTAL  latter  is  the  larger.  The  frontal  nerve  runs  for- 

NERVE.  wards  upon  the  upper  surface  of  the  levator 

palpebrse,  on  which,  about  midway  in  the  orbit,  it  divides  into  two 
branches,  the  supra-trochlear  and  the  supra-orbital. 

a.  The  supra-trochlear  runs  obliquely  inwards  above  the  pulley  of 


LACHRYMAL    GLAND.  209 

the  superior  oblique  to  the  inner  angle  of  the  orbit.  Here  it  gives  off 
a  small  communication  to  the  infra-trochlear  branch  of  the  nasal,  and 
then  divides,  after  passing  between  the  bone  and  the  orbicularis  palpe- 
brarum,  into  filaments  which  supply  the  skin  of  the  upper  eyelid,  forehead, 
and  nose.  One  or  two  small  filaments  may  be  traced  through  the  bone 
to  the  mucous  membrane  of  the  frontal  sinuses.* 

b.  The  supra-orbital  is  the  continuation  of  the  frontal  nerve,  and 
runs  forwards  to  the  supra-orbital  notch,  through  which  it  ascends  to 
supply  the  skin  of  the  upper  eyelid,  forehead,  and  scalp.  Its  cutaneous 
branches,  an  inner  and  an  outer,  which  run  upwards  beneath  the 
occipito-frontalis,  have  been  described  in  the  dissection  of  the  scalp 
(p.  4). 

LACHRYMAL  This  is  the  smallest  of  the  three  branches  of  the 

NEBVE.  ophthalmic  nerve.  It  runs  along  the  outer  side 

of  the  orbit  with  the  lachrymal  artery,  through  the  lachrymal  gland, 
which  it  supplies  as  well  as  the  upper  eyelid.  Its  branches  within 
the  orbit  are :  1,  a  branch  which  passes  down  behind  the  lachry- 
mal gland  to  communicate  with  the  orbital  branch  of  the  superior 
maxillary  nerve ;  2,  filaments  to  the  lachrymal  gland.  It  then 
pierces  the  palpebral  ligament  to  supply  the  skin  of  the  upper 
eyelid. 

FOURTH  CEA-  This  nerve  enters  the  orbit  through  the  sphe- 

NIAL  NERVE.  noidal  fissure  above  the  other  nerves.  It  runs 

along  the  inner  side  of  the  frontal  nerve,  and  enters  the 
orbital  surface  of  the  superior  oblique,  to  which  it  is  solely  dis- 
tributed.f 

LACHRYMAL  This  gland  is  situated  below  the  external 

GLAND.  angular  process  of  the  frontal  bone.  It  is  about 

the  size  and  shape  of  an  almond.  Its  upper  surface  is  convex,  in 
adaptation  to  the  roof  of  the  orbit ;  its  lower  is  concave,  in  adap- 
tation to  the  eyeball.  The  anterior  part  of  the  gland  lies  some- 
times separated  from  the  rest,  close  to  the  back  part  of  the 
upper  eyelid,  and  is  covered  by  the  conjunctiva.  The  whole 

*  These  filaments  have  been  described  by  Blumenbach — '  De  sinibus  Frontal.' 
f  This  nerve  is  joined  in  the  outer  wall  of  the  cavernous  sinus  by  filaments  from 

the  sympathetic.    Here  also  it  sends  backwards  two  or  more  filaments  to  supply  the 

tentorium  cerebelli. 


210 


LACHETMAL   GLAND. 


FIG.  41. 


gland  is  invested  by  a  capsule  *  formed  by  the  fascia  of  the 
orbit. 

The  lachrymal  gland  consists  of  an  aggregation  of  small  lobes 
composed  of  smaller  lobules,  connected  by  fibre-cellular  tissue, 

and  resembles  the  structure  of  the 
salivary  glands.  The  excretory  ducts, 
seven  to  ten  in  number,  run  parallel, 
and  perforate  the  conjunctiva  about 
a  quarter  of  an  inch  above  the  edge 
of  the  tarsal  cartilage  (fig.  41). 
They  are  not  easily  discovered  in 
the  human  eye ;  in  that  of  the 
horse  or  bullock  they  are  large 
enough  to  admit  a  small  probe. 
The  secretion  of  the  gland  keeps 
the  surface  of  the  cornea  constantly 
moist  and  polished ;  but  if  dust,  or 

any  foreign  substance,  irritate  the  eye,  the  tears  flow  in  abundance, 
and  wash  it  off. 

All  the  muscles  of  the  orbit,  with  the  exception  of  the  inferior 
oblique,  arise  from  the  margin  of  the  foramen  opticum,  and  saps 
forwards,  like  ribands,  to  their  insertions. 

LEVATOB  This  muscle  arises  from  the  roof  of  the  orbit, 

PALPEBRJE.  above  and  in  front   of  the   optic   foramen.     It 

gradually  increases  in  breadth,  and  terminates  in  a  broad,  thin 
aponeurosis,  which  is  inserted  into  the  upper  surface  of  the  tarsal 
cartilage  beneath  the  palpebral  ligament.  It  is  constantly  in 
action  when  the  eyes  are  open,  in  order  to  counteract  the  ten- 
dency of  the  lids  to  fall.  As  sleep  approaches,  the  muscle  relaxes, 
the  eyes  feel  heavy,  and  the  lids  close.  Its  nerve  comes  from  the 
superior  division  of  the  third  nerve,  and  enters  it  on  its  under  or 
ocular  aspect.  . 

*  This  capsule,  being  a  little  stronger  on  the  under  surface  of  the  gland,  is  de- 
scribed and  figured  by  Scemmerring  as  a  distinct  ligament,  '  Icones  Oculi  Humani,' 
tab.  vii. 


MUSCLES   IN   THE    ORBIT.  211 

OBLIQUUS  This  muscle  arises  from  the  inner  side  of  the 

SCPEHIOB.  foramen  opticum.     It  runs  along  the  inner  side 

of  the  orbit,  and  terminates  in  a  round  tendon,  which  passes  through 
a  cartilaginous  pulley — trochlea — attached  to  the  anterior  and 
inner  part  of  the  roof  of  the  orbit.  From  this  pulley  the  tendon 
is  reflected  outwards  and  backwards  to  the  globe  of  the  eye.  It 
gradually  expands,  and  is  inserted  into  the  outer  and  back  part 
of  the  sclerotic  coat,  between  the  external  and  superior  recti.  The 
pulley  is  lined  by  a  synovial  membrane,  which  is  continued  upon 
the  tendon.  The  action  of  this  muscle  will  be  considered  with 
that  of  the  inferior  oblique  (p.  217).  It  is  supplied  by  the  fourth 
nerve,  which  enters  the  back  part  of  its  upper  surface. 

The  frontal  nerve  and  levator  palpebrae  should  now  be  cut 
through  the  middle  and  reflected,  to  expose  the  superior  rectus 
muscle. 

FOUB  RECTI  These  four   muscles   have   a   tendinous   origin 

MUSCLES.  round  the  foramen  opticum,  so  that,  collectively, 

they  embrace  the  optic  nerve.  They  diverge  from  each  other,  one 
above,  one  below,  and  one  on  each  side  of  the  optic  nerve ;  and 
are  named,  accordingly,  rvctus  superior,  inferior,  externus,  and 
internus.  Their  broad  thin  tendons  are  inserted  into  the  sclerotic 
coat  of  the  eye,  about  a  quarter  of  an  inch  from  the  margin  of 
the  cornea  (fig.  42). 

The  external  rectus  not  only  arises  from  the  circumference  of 
the  optic  foramen,  but  has  another  origin  from  the  lower  margin  of 
the  sphenoid  fissure.  Between  these  origins  pass  the  third  nerve, 
the  nasal  branch  of  the  fifth,  the  sixth,  and  the  ophthalmic  vein. 

The  recti  muscles  enable  us  to  direct  the  eye  towards  different 
points ;  hence  the  names  given  to  them  by  Albinus — attollens, 
depressor,  adductor,  and  abductor  oculi.  It  is  obvious  that  by 
the  single  action  of  one,  or  the  combined  action  of  two,  the  eye 
can  be  turned  towards  any  direction. 

The  rectus  superior  is  supplied  by  the  upper  division  of  the 
third  nerve ;  the  rectus  internus,  the  rectus  inferior  and  obliquus 
inferior,  by  the  lower  division.  The  rectus  externus  is  supplied  by 
the  sixth. 

p  2 


212 


MUSCLES   IN   THE    ORBIT. 


Fig.  42. 


Follow  the  recti  to  the  eye,  in  order  to  see  the  tendons  by  which 
they  are  inserted.  Notice  also  the  anterior  ciliary  arteries,  which 
run  to  the  eye  along  the  tendons.  The  congestion  of  these  little 

vessels  occasions  the  red  zone  round 
the  cornea  in  iritis.  It  has  been 
already  mentioned  that  the  tendons 
are  invested  by  a  fascia,  which 
passes  from  one  to  the  other,  form- 
ing a  loose  tunic — capsule  of  Tenon 
— over  the  back  of  the  eye.  This 
tunic  consists  of  two  layers  with 
an  intermediate  space,  lined  with 
flat  cells,  thus  allowing  free  mo- 
bility of  the  globe.  It  is  this 
fascia  which  resists  the  passage  of 
INSERTION  OF  THE  RECTI  MUSCLES  WITH  the  hook  in  the  operation  for  the 

THE   ANTEEIOE   CILIAET   ARTERIES.  f  ...  -,-,  /.,  ,, 

cure  oi  squinting.     Even  alter  the 

complete  division  of  the  tendon,  the  eye  may  still  be  held  in  its 
faulty  position,  if  this  tissue,  instead  of  possessing  its  proper 
softness  and  pliancy,  happen  to  have  become  contracted  and  un- 
yielding. Under  such  circumstances  it  is  necessary  to  divide  it 
freely  with  the  scissors. 

By  removing  the  conjunctival  coat  of  the  eye,  the  tendons  of 
the  recti  are  soon  exposed.  The  breadth  and  the  precise  situation 
of  their  insertion  deserve  attention  in  reference  to  the  operation 
for  strabismus.  The  breadth  of  their  insertion  is  about  three- 
eighths  of  an  inch,  but  the  line  of  this  insertion  is  not,  at  all 
points,  equidistant  from  the  cornea.  The  centre  of  the  insertion 
is  nearer  to  the  cornea  by  about  one  line  than  either  end.  Taking 
the  internal  rectus,  which  has  most  frequently  to  be  divided  in 
strabismus,  we  find  that  the  centre  of  its  tendon  is,  upon  an 
average,  three  lines  only  from  the  cornea,  the  lower  part  nearly 
five  lines,  and  the  upper  four.  It  is,  therefore,  very  possible  that 
the  lower  part  may  be  left  undivided  in  the  operation,  being  more 
in  the  background  than  the  rest.  The  tendon  of  the  internal 
rectus  is  nearer  to  the  cornea  than  either  of  the  others. 


NASAL   NERVE.  213 

The  superior  rectus  should  now  be  reflected :  in  doing  so,  ob- 
serve the  branch  from  the  upper  division  of  the  third  nerve,  which 
supplies  it  and  the  levator  palpebrse.  After  the  removal  of  a 
quantity  of  fat,  we  expose  the  following  objects: — 1,  the  optic 
nerve ;  2,  the  nasal  nerve,  the  ophthalmic  artery  and  vein,  all  of 
which  cross  obliquely  over  the  optic  nerve  from  without  inwards ; 
3,  the  inferior  division  of  the  third  nerve ;  4,  deeper,  towards  the 
back  of  the  orbit,  between  the  optic  nerve  and  the  external  rectus, 
is  situated  the  ophthalmic  or  lenticular  ganglion  with  its  ciliary 
branches;  5,  the  sixth  nerve  entering,  the  ocular  aspect  of  the 
rectus  externus. 

This  is  one  of  the  three  divisions  of  the  oph- 
thalmic branch  of  the  fifth  pair  (fig.  40,  p.  207). 
It  enters  the  orbit  through  the  sphenoidal  fissure  between  the  two 
origins  of  the  external  rectus,  and  then  crosses  obliquely  over  the 
optic  nerve,  beneath  the  levator  palpebrse  and  the  superior  rectus, 
towards  the  inner  wall  of  the  orbit.  After  giving  off  the  infra- 
trochlear  branch,  the  nerve  passes  out  of  the  orbit  between  the 
superior  oblique  and  internal  rectus,  through  the  anterior  ethmoidal 
foramen,  into  the  cranium,  where  it  lies  beneath  the  dura  mater, 
upon  the  cribriform  plate  of  the  ethmoid  bone.  It  soon  leaves  the 
cranium  through  the  nasal  slit  near  the  crista  galli,  and  enters  the 
nose.  Here  it  sends  filaments  to  the  mucous  membrane  of  the  upper 
part  of  the  septum,  and  superior  spongy  bone;  but  the  main  con- 
tinuation of  the  nerve  runs  behind  the  nasal  bone,  becomes  super- 
ficial between  the  bone  and  the  cartilage,  and,  under  the  name  of 
naso-lobular,  is  distributed  to  the  skin  of  the  ala  and  tip  of  the 
nose  (p.  74). 

The  nasal  nerve  gives  off  the  following  branches  in  the  orbit : — - 

a.  One  slender  filament  to  the  lenticular  ganglion  (forming  its  upper 
or  long  root)  is  given  off  from  the  nasal  nerve  as  it  passes  between  the 
heads  of  the  external  rectus.     It  is  about  half  an  inch  long,  and  enters 
the  posterior-superior  angle  of  the  ganglion. 

b.  Two  or  three  long  ciliary  nerves.     They  run  along  the  inner  side 
of  the  optic  nerve  to  the  back  of  the  globe  of  the  eye.     They  are  joined 


214  OPHTHALMIC    AKTEKT. 

by  filaments  from  the  lenticular  ganglion,  and  pass  through  the  sclerotic 
coat  to  supply  the  iris. 

c.  Infra-trochlear  nerve. — This  runs  below  the  pulley  of  the  superior 
oblique,  where  it  communicates  with  the  supra-trochlear  branch  of  the 
frontal  nerve.  It  then  divides  into  filaments,  which  supply  the  skin  of 
the  eyelids,  the  lachrymal  sac,  the  caruncle,  and  the  side  of  the  nose. 

This  nerve,  having  passed  through  the   optic 
foramen,  proceeds  forwards  and  a  little  outwards  to 
the  globe  of  the  eye,  which  it  enters  on  the  nasal  side  of  its  axis. 
It  then  expands  to  form  the  retina.     The  nerve  is  invested  by  a 
fibrous  coat  derived  from  the  dura  mater.     At  the  optic  foramen 
it  is  surrounded  by  the  tendinous  origins  of  the  recti;  in  the  rest 
of  its  course,  by  loose  fat  and  by  the  ciliary  nerves  and  arteries. 
It  is  pierced  in  its  course  through  the  orbit  by  the  arteria  cen- 
tralis  retina?  which  runs  in  the  middle  of  the  nerve  to  the  eyeball. 
OPHTHALMIC  This  artery  arises  from  the  internal  carotid.    It 

AKTEKT.  enters  the  orbit  through  the  optic  foramen,  out- 

side the  optic  nerve;  occasionally  through  the  sphenoidal  fissure. 
Its  course  in  the  orbit  is  remarkably  tortuous.  Situated  at  first 
on  the  outer  side  of  the  optic  nerve,  it  soon  crosses  over  it,  and 
runs  along  the  inner  side  of  the  orbit,  to  inosculate  with  the  in- 
ternal angular  artery  (the  terminal  branch  of  the  facial).  Its 
branches  arise  in  the  following  order: — 

a.  Lachrymal  artery, — This  branch  proceeds  along  the  outer  wall  of 
the  orbit  to  the  lachrymal  gland.     After  supplying  the  gland,  it  termi- 
nates in  the  upper  eyelid.     It  anastomoses  with  the  deep  temporal  arte- 
ries, and  with  a  branch  from  the  arteria  meningea  media. 

b.  Supra-orbital  artery. — This  branch  runs  forwards  with  the  frontal 
nerve  under  the  roof  of  the  orbit,  and  emerges  on  the  forehead  threugh 
the  supra-orbital  notch.     It  inosculates  chiefly  with  the  superficial  tem- 
poral artery. 

c.  Arteria  centralis  retinae. — This  small  branch  enters  the  optic  nerve 
on  the  outer  aspect,  and  runs  in  the  centre  of  this  nerve  to  the  interior 
of  the  eye. 

d.  Ciliary  arteries. — These  branches  proceed   tortuously  forwards 
with  the  optic  nerve.     They  vary  from  twelve  to  fifteen  in  number,  and 
perforate  the  sclerotic  coat  at  the  back  of  the  eye,  to  supply  the  choroid 


OPHTHALMIC  GANGLION.  215 

coat  and  the  iris.  They  are  sometimes  called  short  ciliary,  to  distin- 
guish them  from  the  long  ciliary,  two  in  number,  which  run  on  each 
side  of  the  optic  nerve,  enter  the  sclerotic,  and  extend  horizontally  for- 
wards, one  on  each  side  of  the  globe,  between  the  sclerotic  and  charoid 
coats,  to  the  ciliary  muscle  and  iris.  The  anterior  ciliary  are  branches 
of  the  muscular  arteries,  and  proceed  with  the  tendons  of  the  recti,  and 
enter  the  front  part  of  the  sclerotic  coat.  In  inflammation  of  the  iris 
the  vascular  zone  round  the  cornea  arises  from  enlargement  and  conges- 
tion of  the  anterior  ciliary  arteries. 

e.  Ethmoidal  arteries, — Of  these  arteries,  two  in  number,  the  anterior 
and  larger  passes  through  the  anterior  ethmoidal  foramen  with  the  nasal 
nerve  ;  the  posterior  enters  the  posterior  ethmoidal  foramen.  Both  give 
off  anterior  meningeal  branches  to  the  dura  mater,  and  supply  the  mucous 
membrane  of  the  nose,  and  of  the  ethmoidal  cells. 

f.  Muscular  arteries. — These  are  uncertain  in  their  origin,  and  give 
off  the  anterior  ciliary  branches. 

g.  Palpebral  arteries. — These  branches,  a  superior  and  an  inferior 
proceed  from  the  lachrymal,  nasal,  and  supra-orbital  arteries,  and  are  dis- 
tributed to  their  respective  eyelids,  forming  arches  near  the  margin  of  the 
lids  between  the  tarsal  cartilages  and  the  orbicularis  palpebrarum. 

h.  Nasal  artery. — This  branch  may  be  considered  one  of  the  terminal 
divisions  of  the  ophthalmic.  It  leaves  the  orbit  on  the  nasal  side  of  the 
eye  above  the  tendon  of  the  orbicularis,  and  inosculates  with  the  angular 
artery  (termination  of  the  facial).  It  supplies  the  side  of  the  nose  and 
the  lachrymal  sac. 

i.  Frontal  artery. — This  is  the  other  terminal  branch  of  the  oph- 
thalmic. It  emerges  at  the  inner  angle  of  the  eye,  ascends,  and  inoscu- 
lates with  the  supra-orbital  artery. 

OPHTHALMIC  This  commences  at  the  inner  angle  of  the  eye, 

VEIN'  by  a  communication  with  the  frontal  and  angular 

veins.  It  runs  backwards  above  the  optic  nerve  in  a  straighter 
course  than  the  artery,  receives  corresponding  branches,  and  finally 
passes  between  the  two  heads  of  the  external  rectus,  to  terminate 
in  the  cavernous  sinus. 

OPHTHALMIC  Tm's  sma11  ganglion  (o,  fig.  40, p.  207 ), of  reddish 

OR  LENTICULAR  colour,  and  about  the  size  of  a  pin's  head,  is 
GANGLION.  situated  at  the  back  part  of  the  orbit,  between  the 

optic  nerve  and  the  external  rectus.  It  receives  a  sensory  branch 


216  OPHTHALMIC  GANGLION. 

from  the  nasal  nerve,  which  joins  its  posterior  superior  angle;  a 
motor  branch  (from  the  lower  division  of  the  third),  which  enters 
its  posterior,  inferior  angle;  and  it  receives  a  filament  from  the 
sympathetic  plexus  round  the  internal  carotid  artery.  The  gang- 
lion thus  furnished  with  motor,  sensory,  and  sympathetic  roots,  gives 
off  the  short  ciliary  nerves.  They  run  forward  very  tortuously 
with  the  optic  nerve,  pass  through  the  back  of  the  sclerotic  coat, 
where  they  are  joined  by  the  long  ciliary  (from  the  nasal),  and  are 
distributed  to  the  iris  and  the  ciliary  muscle.  Since  the  ciliary 
nerves  derive  their  motor  influence  from  the  third  nerve,  the  iris 
must  lose  its  power  of  contraction  when  this  nerve  is  paralysed. 

THIRD  NERYE,  The  third  nerve,  just  before  it  enters  the  sphe- 

MOTOR  OCULI.  noidal  fissure,  divides  into  two  branches,  both  of 
which  pass  between  the  origins  of  the  external  rectus.  The  upper 
division  has  been  already  traced  into  the  superior  rectus  and 
levator  palpebrse.  The  lower  division  supplies  a  branch  to  the 
internal  rectus,  another  to  the  inferior  rectus,  and  then  runs  along 
the  floor  of  the  orbit  to  the  inferior  oblique  muscle  (fig.  40). 

What  is  the  result  of  paralysis  of  the  third  nerve?  Falling  of 
the  upper  eyelid  (ptosis),  external  squint,  dilatation  and  immo- 
bility of  the  pupil. 

SIXTH  NERVE,  This  nerve  enters  the  orbit  between  the  origins 

MOTOR  EXTEBNUS.  of  the  external  rectus  above  the  ophthalmic  vein, 
and  terminates  in  fine  filaments,  which  are  exclusively  distributed 
to  the  ocular  surface  of  this  muscle. 

Respecting  the  motor  nerves  in  the  orbit,  observe  that  they  all 
enter  the  ocular  surface  of  the  muscles,  with  the  exception  of  the 
fourth  which  enters  the  orbital  surface  of  the  superior  oblique. 

INFERIOR  This  muscle  arises  by  a  flat  tendon  from  the 

OBLIQUE.  orbital  plate  of  the  superior  maxilla  on  the  outer 

side  of  the  lachrymal  groove.  It  runs  outwards  and  backwards  be- 
tween the  orbit  and  the  inferior  rectus,  then  curves  upwards  be- 
tween the  globe  and  the  external  rectus,  and  is  inserted  by  a  broad 
thin  tendon  into  the  outer  and  back  part  of  the  sclerotic,  close  to 
the  tendon  of  the  superior  oblique.  It  is  supplied  by  the  lower 
division  of  the  third  nerve. 


TENSOR   TARSI.  217 

ACTION  OF  THE  The  action  of  the  oblique  muscles  of  the  eye 
OBLIQUE  MUSCLES  will  be  understood  if  a  mark  in  the  iris  be  watched 
OF  THE  EYE.  while  the  head  is  rotated  from  side  to  side  on  its 

antero-posterior  axis.  It  will  be  thus  seen  that  the  eye  does  not 
rotate  on  its  antero-posterior  axis,  as  might  have  been  expected. 
This  is  due  to  the  oblique  muscles  (the  right  superior  acting  with 
the  left  inferior,  and  vice  versa)  which  prevent  the  rotation  of  the 
eye  on  its  antero-posterior  axis  during  the  movements  of  the  head. 
In  other  words,  they  keep  the  vertical  meridian  of  the  eye  always 
vertical. 

This  muscle  is   onlv  a  deeper  part  of  the  orbi- 
TENSOR  TARSI. 

cularis  palpebrarurn.  To  expose  it,  cut  perpen- 
dicularly through  the  middle  of  the  upper  and  lower  lids,  and 
evert  the  inner  halves  toward  the  nose.  After  removing  the 
mucous  membrane,  the  muscle  will  be  seen  arising  from  the 
ridge  of  the  lachrymal  bone.  It  passes  nearly  horizontally  out- 
wards and  divides  into  two  portions,  which  are  inserted  into  the 
upper  and  lower  tarsal  cartilages,  close  to  the  orifices  of  the 
lachrymal  ducts.  It  is  probable  that  the  tensor  tarsi  draws 
backwards  the  open  mouths  of  the  ducts,  so  that  they  may  receive 
the  tears  at  the  inner  angle  of  the  eye.  It  is  supplied  by  a  small 
branch  from  the  facial  nerve. 

ORBITAL  ^^s  *s  a^ways   verv   small>  and  is  sometimes 

BRANCH  OF  THE  absent.  It  comes  from  the  trunk  of  the  superior 
SUPERIOR  MAXIL-  maxillary  in  the  spheno-maxillary  fossa  (fig.  43), 
LARY  NERVE.  enters  the  orbit  through  the  spheno-maxillary  fis- 

sure, and  divides  into  two  branches.  Of  these,  one,  the  temporal,  lies 
in  a  groove  in  the  outer  wall  of  the  orbit,  and  after  sending  a  small 
branch  to  the  lachrymal  nerve  in  the  orbit,  passes  through  a 
foramen  in  the  malar  bone  to  the  temporal  fossa.  It  then  pierces 
the  temporal  aponeurosis  an  inch  above  the  zygoma,  and  supplies 
the  skin  of  the  temple,  joining  frequently  with  the  auriculo- 
temporal  branch  of  the  inferior  maxillary.  The  other  branch,  the 
malar,  passes  along  the  outer  part  of  the  floor  of  the  orbit,  em- 
bedded in  fat,  and  makes  its  exit  through  a  foramen  in  the  malar 
bone,  to  supply  the  skin  of  the  cheek  (p.  94). 


218 


SUPERIOR    MAXILLARY   NERVE. 


DISSECTION  OF  THE  SUPERIOR  MAXILLARY  NERVE. 

To  trace  this  nerve  and  its  branches  we  must  remove  the  outer 
wall  of  the  orbit  as  far  as  the  foramen  rotundum,  so  as  to  expose 
the  spheno-maxillary  fossa. 

The  superior  maxillary  nerve  is  the  second  division  of  the  fifth 
cranial  nerve.  Proceeding  from  the  Gasserian  ganglion  (fig.  43), 

FIG.  43. 


Trunk  of  the 
fifth  nerve  . 

Gasserian  gan- 
glion .  .  . 


Submaxillary 
ganglion 


Frontal,  lachry- 
mal and  nasal 
nn. 

Orbital  branch. 


Infra-orbital  n. 


interior  dental 

n. 

Naso-palatine  n. 
Palatine  n. 


Gustatory  n. 


DIAGRAM   OF   THE   StJPEBIOB   MAXILLABT  NEBVE. 
1.  Spheno-palatine  ganglion.  2.  Otic  ganglion. 

it  leaves  the  skull  through  the  foramen  rotundum,  and  passes  hori- 
zontally forwards  across  the  spheno-maxillary  fossa.  It  then  passes 
into  the  orbit  through  the  spheno-maxillary  fissure,  enters  the 
infra-orbital  canal  with  the  corresponding  artery,  and  finally 
emerges  upon  the  face,  through  the  infra-orbital  foramen,  beneath 
the  levator  labii  superioris.  The  branches  given  off  are  : — 

a.  The  orbital  branch  already  described  (p.  217). 

b.  Two  branches,  which  descend  to  the   spheno-palatine  ganglion 
(Meckel's),  situated  in  the  spheno-maxillary  fossa  (p.  220). 


SUPERIOR    MAXILLARY    NERVE. 


219 


c.  Posterior  dental  branches,  two  in  number.     They  descend  along 
the  back  part  of  the  superior  maxillary  bone.      One  lies  between  the 
periosteum  and  the  bone,  and  supplies  the  gums  and  mucous  membrane  ; 
the  other  passes  through  a  foramen  in  company  with  a  small  artery,  and 
running  in  an  osseous  canal  supplies  the  molar  teeth  and  the  antrum ;  it 
gives  off  also  a  small  branch  which  communicates  with  the  anterior  den- 
tal nerve. 

d.  Anterior  dental  branch. — This  is  given  off  just  before  the  nerve 
emerges  from  the  infra-orbital  foramen.     It  descends  in  a  special  canal 

FIG.  44. 


DEEP  VIEW   OF   THE   SPHEXOPALATINE   GANGLION,    AND    ITS   CONNECTION   WITH   OTHER 

NEBVES.     (After  Hirschfeld.) 


Superior  marillary  n. 

Spheno-palatine  ganglion,  from  the  lower  part 

of  which  are  seen  proceeding  the  palatine 

nerves. 

Posterior  superior  dental  brs. 
Sixth  n.  receiving  two  filaments  from  the 

carotid  plexus  of  the  sympathetic  n. 
The  carotid  br.  of  the  Vidian. 
The  great  petrosal  br.  of  the  Vidian. 
Lesser  petrosal  nerve. 
External  deep  petrosal  n.,  uniting  with  lesser 

petrosal  n. 


9.  The  internal  deep  petrosal  nerve  joining  the 
great  petrosal  nerve. 

10.  Filament  to  f  enestra  ovalis. 

11.  Filament  to  Eustachian  tube. 

12.  Filament  to  fenestra  rotunda, 

13.  Chorda  tympaui. 

14.  Infra- orbital  nerve. 

15.  Anterior  dental  n. 

16.  Junction  of   posterior  and  anterior  dental 

filaments. 

17.  Grlosso-pharyngeal  n.   giving  off  tympanic 

branch. 


in  the  anterior  wall  of  the  upper  jaw,  and  divides  into  branches,  which 
distribute,  filaments  to  the  incisor,  canine,  and  bicuspid  teeth,  the  mu- 
cous membrane  of  the  antrum  and  the  gums. 


220  SPHENO-PALATINE    GANGLION. 

e.  The  terminal  branch,  the  infra-orbital,  was  dissected  with  the 
face  (p.  93). 

At  this  stage  of  the  dissection,  make  a  vertical 

DISSECTION.  ...  ,.°  .  ,        .  ,.  .,,,     ,.  , 

incision  rather  on  one  side  of  the  middle  line  ot 

the  skull,  to  expose  the  cavity  of  the  nose.  Thus,  by  searching  for 
the  spheno-palatine  foramen,  we  are  enabled  to  expose  the  spheno- 
palatine  ganglion.  This  may  be  readily  made  out  by  tracing  the 
terminal  branch  of  the  internal  maxillary  artery  which  comes 
through  the  foramen  into  the  nose.  The  student  should  next  cut 
away  the  thin  plate  of  bone  which  forms  the  inner  boundary  of  the 
palatine  canal.  Then,  by  tracing  upwards  the  branches  contained 
within  the  canal,  he  will  find  the  ganglion. 

SPHENO-PALA-  This  ganglion   is   called,   after   its   discoverer, 

TINE  GANGLION.  MeckeUs  ganglion.  It  is  about  the  fifth  of  an  inch 
in  diameter.  It  is  situated  in  the  spheno-m axillary  fossa,  imme- 
diately on  the  outer  side  of  the  spheno-palatine  foramen.  Like 
other  ganglia,  it  has  three  roots,  a  sensory,  from  the  superior 
maxillary  ;  a  motor,  from  the  great  petrosal  branch  of  the  facial ; 
and  a  sympathetic,  from  the  carotid  plexus. 

Its  branches  pass  upwards  to  the  orbit ;  downwards  to  the 
palate ;  inwards  to  the  nose ;  and  backwards  to  the  pharynx,  as 
follows : — 

a.  Ascending   branches. — These   are   very   small,  and   run   through 
the  spheno-maxillary  fissure  to  be  distributed  to  the  periosteum  of  the 
orbit.* 

b.  Descending  branches. — To  see  these  the  mucous  membrane  must 
be  removed  from  the  back  part  of  the  nose  :  we  shall  then  be  able  to 
trace  the  nerves  through  their  bony  canals.     Their  course  is  indicated  by 
their  accompanying  arteries.     They  descend  through  the  palatine  canals, 
and  are  three  in  number.      The  anterior  palatine  nerve,  the  largest,  de- 
scends through  the  posterior  palatine  canal  to  the  roof  of  the  mouth,  and 
then  divides  into  branches,  which  run  in  grooves  in  the  hard   palate 
nearly  to  the  gums  of  the  incisor  teeth,  where  it  communicates  with  the 

*  Anatomists  describe  several  branches  ascending  from  the  ganglion,  one  to  join 
the  sixth  nerve,  another  to  join  the  ophthalmic  ganglion,  and,  lastly,  some  to  join  the 
optic  nerve  through  the  ciliary  branches, 


SPHENO-PALATINE    GANGLION.  221 

naso -palatine  nerve.  Within  its  canal  it  sends  two  nasal  branches  which 
supply  the  membrane  on  the  middle  and  lower  spongy  bones.  The 
smaller  palatine  descends  in  the  same  canal  with  the  anterior,  or  in  a 
smaller  one  of  its  own,  and  supplies  the  mucous  membrane  of  the  soft 
palate,  the  tonsil,  and  (according  to  Meckel)  the  levator  palati  muscle.* 
The  external  palatine  may  be  traced  in  a  special  canal  down  to  the  soft 
palate,  where  it  terminates  in  branches  to  the  uvula,  the  palate,  and  tonsil. 

c.  Internal  branches. — These,  three  or  four  in  number,  pass  through 
the  spheno-palatine  foramen  to  the  mucous  membrane  of  the  nose.     To 
see   them   clearly,  the  parts  should  have  been  steeped  in  dilute  nitric 
acid ;    afterwards,  when  well  washed,  these  minute  filaments  may  be 
recognised  beneath  the  mucous  membrane  covering  the  spongy  bones. 
The  upper  nasal  branches  pass  inwards,  and  are  distributed  on  the  two 
upper  spongy  bones,  the  upper  and  back  part  of  the  septum  and  the 
posterior  ethmoidal  cells.     The  naso-palatine  traverses  the  roof  of  the 
nose,  distributes  branches  to  the  back  part  of  the  septum  narium,  and 
then  proceeds  obliquely  forwards,  along  the  septum,  to  the  foramen  in- 
cisivum,  through  which  it  passes,  and  finally  terminates  in  the  palate 
behind  the  incisor  teeth  communicating  here  with  the  anterior  palatine 
nerve. 

d.  Posterior  branches. — The  pharyngeal  nerve,  very  small,  comes  off 
from  the  back  of  the  ganglion,  and,  after  passing  through  the  pterygo- 
palatine  canal  with  its  corresponding  artery,  supplies  the  mucous  membrane 
of  the  back  of  the  pharynx  and  the  Eustachian  tube.     The  Vidian  nerve 
is  the  principal  branch.     It  proceeds  backwards  from  the  posterior  part 
of  the  ganglion,  through  the  Vidian  canal.     It  then  traverses  the  fibro- 
cartilage  of  the  foramen  lacerum  medium,  and  divides  into  two  branches. 
Of  these  two  branches,  one — the  carotid — joins  the  sympathetic  plexus 
on  the  outer  side  of  the  internal  carotid  artery ;  the  other,  the  great 
petrosal,  enters  the  cranium,  and  runs  beneath  the  Gasserian  ganglion 
and  the  dura  mater  in  a  small  groove  on  the  anterior  surface  of  the  petrous 
bone  :  it  then  enters  the  hiatus  Fallopii,  and  joins  the  facial  nerve  in  the 
aquseductus  Fallopii. 

*  According  to  Longet  (' Anat.  et  Physiol.  du  Systeme  Nerveux,'  Paris,  1842), 
the  posterior  palatine  nerve  supplies  the  levator  palati  and  the  azygos  uvulae  with 
motor  power.  In  this  view  of  the  subject  the  nerve  is  considered  to  be  the  continua- 
tion or  terminal  branch  of  the  motor  root  of  the  ganglion  :  that,  namely,  derived  from 
the  facial.  This  opinion  is  supported  by  cases  in  which  the  uvula  is  stated  to  have 
been  drawn  on  one  side  in  consequence  of  paralysis  of  the  opposite  facial  nerve. 


222  OTIC    GANGLION. 

It  would  seem  to  be  more  in  accordance  with  modern  views  to  regard 
the  Vidian  nerve,  not  as  dividing  to  form  the  carotid  and  great  superficial 
petrosal  branches,  but  rather  as  formed  by  the  junction  of  these  branches. 
In  this  view,  the  Vidian  runs,  not  from,  but  to  the  spheno-palatine 
ganglion. 

The  otic  ganglion  is  situated  on  the  inner  side 
of  the  inferior  maxillary  division  of  the  fifth  nerve, 
immediately  below  its  exit  through  the  foramen  ovale  (fig.  44). 
Its  inner  surface  is  in  contact  with  the  circumflexus  palati  muscle 
and  the  cartilage  of  the  Eustachian  tube,  and  immediately  behind 
it  is  the  middle  meningeal  artery.  It  is  always  small.* 

This  ganglion  has  branches  of  connection  with  other  nerves : 
namely, — a  sensory  from  the  auriculo-temporal  nerve ;  a  motor 
from  the  branch  of  the  inferior  maxillary  which  goes  to  the 
internal  pterygoid  muscle  ;  and  a  sympathetic  from  the  plexus 
around  the  arteria  meningea  media.  It  communicates  also  with 
the  facial  and  the  glosso-pharyngeal  nerves  by  the  lesser  petrosal 
nerve.  This  branch  passes  backwards  either  through  the  foramen 
ovale  or  the  foramen  spinosum,  or  through  a  small  hole  between 
them,  and  runs  beneath  the  dura  mater  in  a  minute  groove  on 
the  petrous  bone,  external  to  that  for  the  great  petrosal  nerve. 
Here  it  divides  into  two  filaments,  one  of  which  joins  the  facial 
nerve  in  the  aquaeductus  Fallopii,  the  other  joins  the  tympanic 
branch  of  the  glosso-pharyngeal.  These  nerves  are  difficult  to  trace, 
not  only  on  account  of  their  minuteness,  but  because  they  frequently 
run  in  canals  in  the  temporal  bone. 

The  otic  ganglion  sends  a  branch  forwards  to  the  tensor  palati, 
and  one  backwards  to  the  tensor  tympani. 

*  J.  Arnold.     '  Diss.  inaug.  med.,'  &c.     Heidelbergse,  1826. 


DIAGRAM    OF    NERVE-COMMUNICATIONS. 


223 


FIG.  45. 


N.  to  great  petrosal .    . 
N.  to  lesser  petrosal .    . 

N.  to  Eustachian  tube. 
N  s.  to  carotid  plexus    . 

Chorda  tympani .    .    . 
N.  to  stylo-hyoid     .    . 


N.  to  digastricus .    .    . 
Petrous  ganglion .    .     . 


Carotid  plexus     ,     .     . 

Branch  to  pharyngeal 
plexus 

Lingual  branch    .     .    . 
Ganglion  of  the  trunk  . 


Pharyngeal  n.     . 


Superior  laryngeal 


Gangliform  enlarge- 
ment. 

.  tofenestra  ovalis. 
N.   to    fenestra  ro- 
tunda. 


Tympanic  n. 

Auricular  n. 

Glosso-pharyngeal 

n. 
Jugular  ganglion  of 

do. 

Pneumogastric. 
Ganglion  of  root. 

Spinal  accessory. 


Hypoglossal. 


Supr.  cervical  gan- 
glion. 
1st  cervical n. 

Br.    to  ganglion  of 

trunk. 
2nd  cervical  n. 


DIAGRAM  OF  THE  COMMUNICATIONS  OF  THE  FACIAL,  GLOSSO-PHARYNGEAL,  PNEUMO- 
GASTEIC,  SPINAL  ACCESSORY,  HTPOGLOSSAL,  SYMPATHETIC,  AND  THE  TWO  tJPPEB 
CBEVICAL  NERVES. 


1 .  Great  petrosal  nerve. 

2.  Lesser  do. 

3.  External  do. 


4.  Nerve  to  Stapedius  muscle. 

5.  Spheno-palatine  ganglion. 

6.  Ocic  ganglion. 


224  GANGLIA    OP    THE    GLOSSO-PHARYNGEAL. 


DISSECTION   OF   THE  EIGHTH   PAIR    OF   NERVES   AT    THE   BASE 
OF  THE  SKULL. 

In  this  dissection  we  propose  to  examine  the  glosso-pharyngeal, 
pneumogastric,  and  spinal  accessory  nerves  in  the  jugular  fossa, 
and  the  ganglia  and  nerves  belonging  to  them  in  this  part  of  their 
course.  These  are  difficult  to  trace,  and  cannot  be  followed  unless 
the  nerves  have  been  previously  hardened  by  spirit,  and  the  bones 
softened  in  acid.  The  next  thing  to  be  done  is  to  remove  the  outer 
wall  of  the  jugular  fossa. 

GLOSSO-PHA-  This  nerve  emerges  from  the  cranium  through  a 

BYNGEAL  NEHVE.  separate  tube  of  dura  mater,  in  front  of  that  for 
the  other  two  nerves  of  the  eighth  pair.  Looking  at  it  from  the 
interior  of  the  skull,  we  notice  that  it  is  situated  in  front  and 
rather  to  the  inner  side  of  the  jugular  fossa,  where  it  lies  in  a 
groove. 

In  its  passage  through  the  foramen,  the  nerve  presents  two 
enlargements,  termed  the  jugular  and  the  petrous  ganglia. 

The  jugular  ganglion*  is  found  upon  the  nerve  immediately 
after  its  entrance  into  the  canal  of  the  dura  mater,  and  averages 
about  tK  :^-  of  an  inch  in  length  and  breadth.  It  is  situated  on 
the  outer  side  of  the  nerve,  and  does  not  implicate  all  its  fibres. 
According  to  our  observation,  this  ganglion  is  not  infrequently 
absent. 

The  petrous  ganglion^  is  situated  upon  the  glosso-pharyngeal 
nerve,  near  the  lower  part  of  the  jugular  fossa.  It  is  oval,  about 
^  of  an  inch  long,  and  involves  all  the  filaments  of  the  nerve. 
It  is  connected  by  filaments  with  the  pneumogastric  and  sym- 
pathetic nerves,  and  it  gives  off  the  tympanic  nerve.  J  The 
branches  which  connect  this  ganglion  with  the  pneumogastric  are, 
one  to  its  auricular  branch,  and  a  second  to  the  ganglion  of  the 
root.  It  is  also  connected  with  the  sympathetic  by  a  small  fila- 

*  Miiller,  '  Medicin.  Zeitung,'  Berlin,  1833.  No.  52. 
f  Andersch,  'Fragm.  Descript.  Nerv.  Cardiac.'  1791. 
|  This  nerve,  though  commonly  called  Jacobson's,  was  fully  described  by  Andersch. 


PNEUMOGASTRIC  NERVE  AT  THE  BASE  OP  THE  SKULL.   225 

ment  from  the  superior  cervical  ganglion.  The  tympanic  nerve 
ascends  through  a  minute  canal  in  the  bony  ridge  which  separates 
the  carotid  from  the  jugular  fossa  to  the  inner  wall  of  the  tym- 
panum, where  it  terminates  in  six  small  filaments.  Of  these  three 
are  branches  of  distribution,  and  three  of  connection  with  other 
nerves.  The  branches  of  distribution  are,  one  each  to  the  fenestra 
rotunda  and  the  fenestra  ovalis,  and  one  to  the  Eustachian  tube. 
The  connecting  branches  are  two  small  filaments,  which  traverse 
a  bony  canal  to  join  the  plexus  on  the  outer  side  of  the  carotid 
artery:  the  second  ascends  in  front  of  the  fenestra  ovalis  and 
joins  the  great  petrosal  nerve  in  the  hiatus  Fallopii ;  the  third 
takes  nearly  a  similar  course,  and  under  the  name  of  the  lesser 
petrosal  nerve  proceeds  along  the  front  surface  of  the  pars  petrosa 
to  the  otic  ganglion.  Thus  this  tympanic  branch  is  distributed 
to  the  mucous  membrane  of  the  tympanum  and  the  Eustachian 
tube,  and  communicates  with  the  spheno-palatine  ganglion  through 
the  great  petrosal  nerve,  and  with  the  otic  ganglion  through  the 
lesser  petrosal. 

PNEUMOGASTRIC          This  nerve  leaves  the  cranium  with  the  nervus 
NEKVE.  accessorius  through  a  common  canal  in  the  dura 

mater,  behind  that  for  the  glosso-pharyngeal.  At  its  entrance 
into  the  canal,  it  is  composed  of  a  number  of  separate  filaments 
which  are  soon  collected  into  a  single  trunk.  In  the  jugular 
foramen,  the  nerve  presents  a  ganglionic  enlargement,  called  the 
ganglion  of  the  root  of  the  pneumogastric.  This  ganglion* 
is  about  \  of  an  inch  in  length.  It  is  connected  by  filaments 
with  the  sympathetic  through  the  superior  cervical  ganglion,  with 
the  petrous  ganglion  of  the  glosso-pharyngeal,  with  the  facial,  and 
with  the  spinal  accessory  by  one  or  two  branches.  It  gives  off  the 
auricular  branch^  which  is  distributed  to  the  pinna  of  the  ear. 
This  branch  shortly  after  its  origin  is  joined  by  a  branch  from 
the  glosso-pharyngeal,  and  enters  a  minute  foramen  in  the  jugular 
fossa  near  the  sty loid  process.  It  then  proceeds  through  a  canal 
in  the  bone,  crosses  the  aqugeductus  Fallopii,  and  passes  to  the 

*  Arnold,  '  Der  Kopftheil  des  Veget.  Nerveu  Systems.'     Heidelberg,  1831. 
f  Arnold's  nerve. 

Q 


226 


FACIAL    NERVE    IN    THE    TEMPORAL    BONE. 


outside  of  the  head  through  the  fissure  between  the  mastoid 
process  and  the  meatus  auditorius  externus.  It  is  distributed  to 
the  skin  of  the  auricle  and  communicates  with  the  posterior 
auricular  branch  of  the  facial  nerve. 

The  facial  nerve  is  contained  within  the  meatus 
auditorius  internus,  together  with  the  auditory 
nerve.  At  the  bottom  of  the  meatus  the  two 
nerves  are  connected  by  one  or  more  filaments.  The  facial  nerve 
then  enters  the  aquseductus  Fallopii.  This  is  a  tortuous  canal 
in  the  substance  of  the  temporal  bone,  and  terminates  at  the 

Fra.  46. 


FACIAL  NERVE 

IN  THE 

TEMPORAL  BONE, 


1 .  The  chorda  tynipani. 

2.  The  geniculate  ganglion 

of  the  facial  nerve. 

3.  The  great  petrosal  nerve. 

4.  The  lesser  petrosal  nerve 

lying   oyer  the  tensor 
tympani. 


5.  The  external  petrosal 
nerve  communicating 
with  the  sympathetic 
plexus  on  the  arteria 
meningea  media  (6). 

7.  The  Gasserian  ganglion. 


THE   GENICULATE    GANGLION    OF   THE    FACIAL   NEEVE,    AND    ITS    CONNECTIONS    "WITH    THE 

OTHER  N.ERVES.     (From  Bidder.) 

stylo-mastoid  foramen.  The  nerve  proceeds  from  the  meatus  in- 
ternus for  a  short  distance  outwards,  where  it  presents  a  ganglionic 
enlargement ;  it  then  makes  a  sudden  bend  backwards  along  the 
inner  wall  of  the  tympanum  above  the  fenestra  ovalis,  and  lastly, 
curving  downwards  along  the  back  of  the  tympanum,  it  leaves 
the  skull  through  the  stylo-mastoid  foramen.  Its  branches  in 
the  temporal  bone  are  : — 

a.  Communicating  filaments  with  the  auditory  nerve,  in  the  meatus 
auditorius  internus. 

b.  The  great  petrosal  nerve,  which  runs  to  the  spheno-palatine  gang- 
lion.    (Fig.  46.  3.) 


INTERNAL  CAEOTID  AT  THE  BASE  OP  THE  SKULL.    227 

c.  The   lesser    petrosal   nerve,   which   runs   to    the    otic   ganglion. 
(Fig.  46.  4.) 

d.  The  external  petrosal,  which  connects  the  facial  nerve  with  the 
sympathetic  plexus  around  the  middle  meningeal  artery.      (Fig.  46.  5.) 

e.  The  nerve  to  the  Stapedius  muscle,  which  runs  in  the  pyramid.' 
(Fig.  45.  4.) 

f.  The  chorda  tympani,  which  joins  the  submaxillary  ganglion. 

The  chorda  tympani  is  given  off  from  the  facial  nerve  before 
its  exit  from  the  stylo-mastoid  foramen.  It  ascends  a  short 
distance  in  a  bony  canal  at  the  back  of  the  tympanum,  and  enters 
that  cavity  below  the  pyramid,  close  to  the  membrana  tympani. 
It  runs  forward,  ensheathed  in  mucous  membrane,  through  the 
tympanum,  between  the  handle  of  the  malleus  and  the  long  process 
of  the  incus,  to  the  anterior  part  of  that  cavity.  It  then  traverses 
a  special  bony  canal,*  and  emerges  from  the  tympanum  external 
to  the  fissura  Glaseri.  It  subsequently  joins  the  lower  border  of 
the  gustatory  nerve  at  an  acute  angle,  and  proceeds  to  the  sub- 
maxillary  ganglion.  It  is  said  to  supply  the  laxator  tympani 
muscle. f 

COUESE  OF  IN-  ^ke  internal  carotid  takes  a  very  tortuous 
TEENAL  CAEOTID  course  through  the  base  of  the  skull  before  it 
THBOUGH  BASE  OF  reaches  the  brain.  It  makes  no  less  than  four 
curves.  It  first  curves  forwards  and  inwards 
through  the  carotid  canal  of  the  temporal  bone;  it  makes  a  second 
curve  upwards  through  the  cartilage  in  the  foramen  lacerum 
medium ;  it  then  makes  a  third  curve  forwards  on  the  side  of  the 
body  of  the  sphenoid ;  and,  lastly,  a  fourth  curve  upwards  on  the 
inner  side  of  the  anterior  clinoid  process,  after  which  it  enters  the 
cranial  cavity,  gives  off  the  ophthalmic,  and  divides  into  the  an- 
terior cerebral,  the  middle  cerebral,  and  the  posterior  communi- 
cating arteries. 

The  internal  carotid  is  accompanied  in  the  carotid  canal  by 
the  cranial  branch  of  the  superior  cervical  ganglion  of  the  sympa- 
thetic, described  p.  115.  Its  position  on  the  inner  wall  of  the 

*  Canal  of  Huguier.   . 

f  This  is  probably  not  muscular,  but  ligamentous  in  structure. 
Q  2 


228  CARTILAGES    OF    THE    NOSE. 

cavernous  sinus,  and  the  nervous  plexuses  upon  it  are  described  at 
p.  16. 

In  the  carotid  canal  the  artery  gives  off  a  small  branch  to  the  mastoid 
cells  and  the  tympanum. 

At  this  stage  of  the  dissection  we  may  conveniently  trace  the 
anterior  divisions  of  the  two  upper  cervical  nerves. 

SUBOCCIPITAL  The  anterior  division  of  the  first  cervical  or 

NERVE,  suboccipital  nerve  descends  in  front  of  the  trans- 

verse process  of  the  atlas  to  form  a  loop  with  the  second  cervical 
nerve.  It  lies  beneath  the  vertebral  artery,  on  the  inner  side  of 
the  rectus  capitis  lateralis  to  which  it  gives  a  branch ;  and  from 
its  loop  of  communication  with  the  second  nerve,  it  gives  branches 
to  the  recti  antici  muscles.  This  nerve  is  connected  by  filaments 
with  the  superior  cervical  ganglion  of  the  sympathetic,  with  the 
hypoglossal  and  the  pneumogastric  nerves. 

SECOND  CERVI-  The  anterior  division  of  this  nerve  emerges  be- 
CAL  NEBVB.  tween  the  arches  of  the  atlas  and  axis,  and  passes 

between  the  vertebral  artery  and  the  intertrans verse  muscle,  in 
front  of  which  it  sub-divides  into  an  ascending  branch  which  joins 
the  first  cervical  nerve,  and  a  descending,  which  joins  the  third 
cervical  nerve. 


DISSECTION   OF  THE  NOSE. 

Presuming  that  the  dissector  is  familiar  with  the  bones  com- 
posing the  skeleton  of  the  nose,  we  shall  now  describe,  1.  The 
nasal  cartilages;  2.  The  general  figure  and  arrangement  of  the 
nasal  cavities;  3.  The  membrane  which  lines  them;  and,  4.  The 
distribution  of  the  olfactory  nerves. 

CARTILAGES  OF  The  framework  of  the  external  nose  is  formed, 

THE  NOSE.  on  each  side,  by  two  lateral  cartilages;    and  by 

one  in  the  centre,  which  completes  the  septum  between  the  nasal 
fossae. 

The  lateral  cartilages  are  termed,  respectively,  upper  and 
lower.  The  upper,  triangular  in  shape,  is  connected,  superiorly,  to 


CAETILAGES    OF    THE    NOSE.  229 

the  margin  of  the  nasal  and  superior  maxillary  bones  ;  anteriorly  to 
the  cartilage  of  the  septum,  and,  inferiorly,  to  the  lower  cartilage 
by  means  of  a  tough  fibrous  membrane.  The  loiver  is  elongated, 
and  curved  upon  itself  in  such  a  way  as  to  form  not  only  half  the 
apex  but  the  lateral  boundary  of  the  external  opening  of  the  nostrils. 
Superiorly,  it  is  connected  by  fibrous  membrane  to  the  upper 
cartilage ;  internally,  it  is  in  contact  with  its  fellow  of  the  opposite 
side,  forming  the  upper  part  of  the  columna  nasi ;  posteriorly,  it  is 
attached  by  fibrous  tissue  to  the  superior  maxillary  bone :  in  this 
tissue,  at  the  base  of  the  ala,  are  usually  found  two  or  three 
nodules  of  cartilage,,  called  cartilagines  -sesamoidece.  By  their 
elasticity  these  several  cartilages  keep  the  nostrils  continually 
open,  and  restore  them  to  their  ordinary  size  whenever  they  have 
been  expanded  by  muscular  action. 

The  cartilage  of  the  septum  is  placed  perpendicularly  in  the 
middle  line :  it  may  lean  a  little,  however,  to  one  side  or  the 
other,  and  in  some  instances  it  is  perforated,  so  that  the  two  nasal 
cavities  communicate  with  each  other.  The  cartilage  is  smooth 
and  flat,  and  its  outline  is  nearly  triangular.  The  posterior  border 
is  received  into  a  groove  in.  the  perpendicular  plate  of-  the  eth- 
moid ;  the  anterior  border  is  much  thicker  than  the  rest  of  the 
septum,  and  is  connected,  superiorly,  with  the  nasal  bones,  and  on 
either  side  with  the  lateral  cartilages.  The  inferior  border  is 
attached  to  the  vomer  and  the  median,,  ridge  at  the  junction  of  the 
palatine  processes  of  the  superior  maxillae. 

The  muscles  moving  the  nasal  cartilages  have  been  described 
with  the  dissection  of  the  face  (p.  82). 

INTERIOR  OF         .    A  vertical  section  should  be  made  through  the 
THE  NOSE.  right  nasal  cavity,  a  little  on  the  same  side  of  the 

middle  line,  to  expose  the  partly  bony  and  partly  cartilaginous 
partition  of  the  nasal  cavities  (septum  narium).  Each  nasal 
fossa  is  narrower  above  than  below.  The  greatest  perpendicular 
depth  of  each  fossa  is  about  the  centre ;  from  this  point  the  depth 
gradually  lessens  towards  the  anterior  and  the  posterior  openings 
of  the  nose.  Laterally,  each  fossa  is  very  narrow  in  consequence 
of  the  projection  of  the  spongy  bones  towards  the  septum :  this 


230  MEATUSES    OP   THE   NOSE. 

narrowness  in  the  transverse  direction  explains  the  rapidity  with 
which  swelling  of  the  lining  membrane  from  a  simple  cold 
obstructs  the  passage  of  air. 

BOUNDARIES  The  nasal  fossae  are   bounded  by  the  following 

OF  NASAL  FOSSJE.  bones : — superiorly,  by  the  nasal,  the  nasal  spine 
of  the  frontal,  the  cribriform  plate  of  the  ethmoid,  and  the  body  of 
the  sphenoid ;  inferiorly,  by  the  horizontal  plates  of  the  superior 
maxillary  and  palate  bones ;  internally,  is  the  smooth  and  flat 
septum  formed  by  the  perpendicular  plate  of  the  ethmoid,  the 
ridge  formed  by  the  two  nasal  bones,  the  vomer,  the  septal  car- 
tilage, also  by  the  nasal  spine  of  the  frontal,  the  rostrum  of  the 
sphenoid,  and  the  median  ridge  of  the  superior  maxillary  and 
palate  bones  ;  externally,  by  the  superior  maxillary,  the  lachrymal, 
the  ethmoid,  the  palate,  the  inferior  turbinated  bone,  and  the 
internal  pterygoid  plate  of  the  sphenoid. 

MEATUSES  OF  The  outer  wall  of  each  nasal  cavity  is  divided 

THE  NOSK.  by  the  turbinated  bones  into  three  compartments 

— meatuses — of  unequal  size ;  and  in  these  are  orifices  leading  to 
air-cells — sinuses — in  the  sphenoid,  ethmoid,  frontal,  and  superior 
maxillary  bones.  'Each  of 'these  compartments  should  be  separately 
examined. 

a.  The  superior  meatus  is  the  smallest  of  the  three,  and  does 
not  extend  beyond  the  posterior  half  of  the  wall  of  the  nose.  The 
posterior  ethmoidal  and  sphenoidal  cells  open  into  it.  The 
spheno-palatine  foramen  is  covered  by  the  mucous  membrane. 

6.  The  middle  meatus  is  larger  than  the  superior.  At  its  an- 
terior part  a  long  narrow  passage  (infundibulum),  nearly  hidden 
by  a  fold  of  membrane,  leads  upwards  to  the  frontal  and  the 
anterior  ethmoidal  cells.  About  the  middle  a  small  opening  leads 
into  the  antrum  of  the  superior  maxilla  :  this  opening  in  the  dry 
bone  is.  large  and  irregular,  but  in  the  recent  state  it  is  reduced 
nearly  to  the  size  of  a  crow-quill  by  mucous  membrane,  so  that  a 
very  little  swelling  of  the  membrane  is  sufficient  to  close  the  orifice 
entirely. 

^Notice  that  the  orifices  of  the  frontal  and  ethmoid  cells  are 
so  disposed  that  their  secretion  will  pass  away  easily  into  the  nose. 


MEATUSES    OF    THE    NOSE.  231 

But  this  is  not  the  case  with  the  maxillary  cells,  to  empty  which 
the  head  must  be  inclined  on  one  side.  To  see  all  these  openings 
the  respective  turbinated  bones  must  be  raised.  * 

c.  The  inferior  meatus  extends  nearly  along  the  whole  length  of 
the  outer  wall  of  the  nose.  By  raising  the  lower  turbinated  bone, 
we  observe,  towards  the  front  of  the  meatus,  the  termination  of 
the  nasal  duct,  through  which  the  tears  pass  down  from  the 
lachrymal  sac  into  the  nose.  This  sac  and  duct  can  now  be  con- 
veniently examined. 

LACHBTMALSAC  The  lachrymal  sac  and  nasal  duct  constitute 
AND  NASAL  DUCT,  the  passage  through  which  the  tears  are  conveyed 
from  the  lachrymal  ducts  into  the  nose  (p.  81).  The  lachrymal 
sac  occupies  the  groove  on  the  nasal  side  of  the  orbit.  The  upper 
end  is  round  and  closed ;  the  lower  gradually  contracts  into  the 
nasal  duct,  and  opens  into  the  inferior  meatus.  The  sac  is  com- 
posed of  a  strong  fibrous  and  elastic  tissue,  which  adheres  very 
closely  to  the  bone,  and  is  lined  by  mucous  membrane.  Its  front 
surface  is  covered  by  the  tendo  oculi  and  the  fascia  proceeding 
from  it. 

The  nasal  duct  is  from  half  to  three-quarters  of  an  inch  in 
length,  and  is  directed  downwards,  backwards,  and  a  little  out- 
wards. Its  termination  is  guarded  by  a  valvular  fold  of  mucous 
membrane  ;  consequently,  when  air  is  blown  into  the  nasal  passages 
while  the  nostrils  are  closed,  the  lachrymal  sac  does  not  become 
distended.  The  lachrymal  sac  and  the  nasal  duct  are  lined  with 
ciliated  epithelium,  and  the  canaliculi  with  the  squamous  variety. 

Behind  the  inferior  turbinated  bone  is  the  opening  of  the 
Eustachian  tube  (p.  186).  Into  this,  as  well  as  into  the  nasal  duct, 
we  ought  to  practise  the  introduction  of  a  probe.  The  chief  diffi- 
culty is  to  prevent  the  probe  from  slipping  into  the  cul-de-sac 
between  the  tube  and  the  back  of  the  pharynx. 

Mucous  OB  This  membrane  lines  the  cavities  of  the  nose 

SCHNEIDERIAN  and    the    air-cells    communicating   with   it,    and 

MEMBRANE.*  adheres  very  firmly  to  the  periosteum.     Its  con- 

*  Schneider,  '  De  catarrhis.'    Wittenberg,  1660. 


232  MUCOUS   MEMBRANE    OF   THE   NOSE. 

tinuity  may  be  traced  into  the  pharynx,  into  the  various  sinuses, 
into  the  orbits  through  the  iiasal  ducts,  and  into  the  tympana  and 
mastoid  cells  through  the  Eustachian  tubes.  At  the  lower  border 
of  the  turbinated  bones  it  is  disposed  in  thick  and  loose  folds. 
The  membrane  varies  in  thickness  and  vascularity  in  different 
parts  of  the  nasal  cavities.  Upon  the  lower  half  of  the  septum 
and  the  inferior  turbinated  bones,  it  is  much  thicker  than  elsewhere, 
owing  to  a  fine  plexus  of  arteries  and  veins  in  the  submucous 
tissue.  In  the  sinuses  the  mucous  membrane  is  thinner,  less 
vascular,  and  closely  adherent  to  the  periosteum. 

The  great  vascularity  of  the  mucous  membrane  raises  the 
temperature  of  the  inspired  air,  and  pours  out  a  copious  secretion 
which  prevents  the  membrane  from  becoming  too  dry. 

The  mucous  membrane  of  the  nasal  cavities  is  not  lined 
throughout  by  the  same  kind  of  epithelium.  Near  the  nostrils 
the  mucous  membrane  is  furnished  with  papillae,  with  a  squamous 
epithelium  like  the  skin,  and  a  few  small  hairs  (vibrissce).  In 
the  lower  part  of  the  nose — namely,  along  the  respiratory  tract  and 
in  the  sinuses — the  epithelium  is  columnar  and  ciliated  ;  but  in 
the  true  olfactory  region — that  is,  upon  the  superior  and  middle 
turbinated  bones  and  the  upper  half  of  the  septum — the  epithe- 
lium is  columnar,  but  not  ciliated.  In  this  region  the  mucous 
membrane  is  extremely  vascular,  thick,  and  studded  with  simple 
mucous  glands.  The  columnar  epithelial  cells  taper  off  at  their 
deep  ends  into  fine  processes.  Lying  between  these  processes  are 
fusiform  cells,  with  central  well-defined  nuclei,  to  which  the  name 
of  olfactory  cells  has  been  given ;  and  it  is  probable  that  the 
attenuated  processes  which  pass  inwards  from  these  cells  are  in 
direct  connection  with  the  terminal  fibrils  of  the  olfactory 
nerves. 

The  arteries  of  the  nasal  cavities  are  derived  from  the  an- 
terior and  posterior  ethmoidal  branches  of  the  opththalmic,  and 
from  the  nasal  branch  of  the  internal  maxillary,  which  enters 
the  nose  through  the  spheno-palatine  foramen.  The  external  nose 
is  supplied  by  the  nasal  branch  of  the  ophthalmic  (p.  215),  the 
arteria  lateralis  nasi,  the  angular,  and  the  artery  of  the  septum. 


MUCOUS  MEMBRANE  OP  THE  NOSE.  233 

The  veins  of  the  nose  correspond  with  the  arteries.  They 
communicate  with  the  veins  within  the  cranium  through  the 
foramina  in  the  cribriform  plate  of  the  ethmoid  bone ;  also 
through  the  ophthalmic  vein  and  the  cavernous  sinus.  These  com- 
munications explain  the  relief  frequently  afforded  by  haemorrhage 
from  the  nose  in  cases  of  cerebral  congestion. 

The  mucous  membrane  of  the  nose  is  supplied  with  sensory 
nerves  by  the  fifth  pair.  Thus,  its  roof  is  supplied  with  filaments 
from  the  external  branch  of  the  nasal  nerve,  and  from  the  Vidian ; 
its  outer  wall,  by  filaments  from  the  superior  nasal  branches  of 
the  spheno-palatine  ganglion,  from  the  nasal,  from  the  inner  branch 
of  the  anterior  dental,  and  from  the  inferior  nasal  branches  of  the 
large  palatine  nerve ;  its  septum,  by  the  septal  branch  of  the 
nasal  nerve,  by  the  nasal  branches  of  the  spheno-palatine  ganglion, 
by  the  naso-palatine,  and  by  the  Vidian :  its  floor,  by  the  naso- 
palatine,  and  the  inferior  nasal  branches  of  the  large  palatine  nerve. 
OLFACTORY  The  olfactory  nerves,  proceeding  from  each 

NERVES.  olfactory  bulb,  in  number  about  twenty  on  each 

side,  pass  through  the  foramina  in  the  cribriform  plate  of  the 
ethmoid  bone.  In  its  passage  each  nerve  is  invested  with  a  coat 
derived  from  the  dura  mater.  They  are  arranged  into  an  inner, 
a  middle,  and  an  outer  set.  The  inner,  which  are  the  largest, 
traverse  the  grooves  in  the  upper  third  of  the  septum.  The 
middle  ramify  on  the  roof  of  the  nose.  The  outer  pass  through 
grooves  in  the  upper  and  middle  turbinated  bones  and  the  os 
planum  of  the  ethmoid. 

The  nerves  descend  between  the  mucous  membrane  and  the 
periosteum,  and  break  up  into  filaments  which  communicate  freely 
with  one  another,  and  form  minute  plexuses  with  small  elongated 
intervals.  Microscopically,  the  filaments  differ  from  the  other 
cerebral  nerves,  in  containing  no  white  substance  of  Schwann,  and 
in  being  pale,  finely  granular,  and  nucleated. 


234  MUSCLES    OP    THE    BACK. 


DISSECTION   OF   THE  MUSCLES   OF  THE   BACK. 

Those  muscles  of  the  back — namely,  the  trapezius,  latissimus 
dorsi,  levator  anguli  scapulae,  and  rhomboidei — which  are  concerned 
in  the  movements  of  the  upper  extremity,  will  be  examined  in  the 
dissection  of  the  arm.  These,  therefore,  having  been  removed,  we 
proceed  to  examine  two  muscles,  named,  from  their  appearance, 
serrati,  which  extend  from  the  spine  to  the  ribs. 

SERRATUS  Pos-  This  muscle  is  situated  beneath  the  rhomboidei. 

TICUS  SUPERIOR.  it  is  a  thin  flat  muscle  and  arises  from  the 
lower  part  of  the  ligamentum  nuchog,*  from  the  spines  of  the  last 
cervical,  and  two  or  three  upper  dorsal  vertebrae,  by  a  sheet-like 
aponeurosis  which  makes  up  nearly  half  the  muscle  :  the  fibres  run 
obliquely  downwards  and  outwards,  and  are  inserted  by  four  fleshy 
slips  into  the  second,  third,  fourth,  and  fifth  ribs  beyond  their 
angles.  Its  action  is  to  raise  these  ribs,  and  therefore  to  assist  in 
inspiration. 

SERRATUS  Pos-  This  muscle  is  situated  beneath  the  latissimus 

TICUS  INFERIOR.  dorsi.  It  arises  from  the  spines  of  the  two  last 
dorsal  and  two  upper  lumbar  vertebrae  by  means  of  the  lumbar 
aponeurosis.  It  ascends  obliquely  outwards,  and  is  inserted  by 
four  fleshy  slips  into  the  four  lower  ribs,  external  to  their  angles. 
Its  action  is  to  pull  down  these  ribs,  and  therefore  to  assist  in 
expiration  The  posterior  serrati  muscles  are  supplied  by  the 
posterior  divisions  of  the  spinal  nerves. 

VERTEBRAL  The  thin  aponeurosis  which  separates  the 

APONEUROSIS.  muscles  of  the  upper  extremity  from  those  of  the 

back  is  called  vertebral  aponeurosis.  Superiorly,  it  is  continued 
beneath  the  serratus  posticus  superior ;  inferiorly,  it  binds  down 
the  muscles  contained  in  the  vertebral  groove,  by  stretching 

*  The  ligamentum  nuchse  is  a  rudiment  of  the  great  elastic  ligament  of  quadru- 
peds (termed  the  pack  wax)  which  supports  the  weight  of  the  head.  It  proceeds  from 
the  spine  of  the  occiput  to  the  spines  of  all  the  cervical  vertebrae  except  the  atlas ; 
otherwise  it  would  interfere  with  the  free  rotation  of  the  head. 


MUSCLES    OF    THE    BACK.  235 

across  from  the  spinous  processes  to  the  angles  of  the  ribs :  it  is 
also  connected  below  with  the  aponeurosis  of  the  latissimus  dorsi 
and  the  serratus  inferior. 

This    aponeurosis  consists   of  three   layers,  of 
LUMBAR  FASCIA.         ,  .   ,     .     ,      . ,  ,  , 

which  only  the  posterior  layer  can  now  be  seen  ; 

the  other  two  being  demonstrated  in  the  dissection  of  the  abdominal 
muscles.  The  posterior  or  superficial  layer  is  attached  to  the  crest 
of  the  ilium,  to  the  spinous  processes  of  all  the  lower  dorsal, 
lumbar,  and  sacral  vertebrae ;  it  forms  a  sheath  for  the  erector 
spinse,  and  serves  for  the  attachment  of  the  latissimus  dorsi,  and 
the  serratus  posticus  inferior. 

The  serratus  posticus  superior  must  now  be  reflected  from  its 
origin,  and  turned  outwards  to  expose  the  following  muscle. 

This  arises  from  the  spines  of  the  five  or  six 

upper  dorsal  and  the  last  cervical  vertebra,  and 

from  the  lower  half  of  the  ligamentum  nuchse.     The  fibres  ascend 

and  divide  into  two  portions,  named,  according  to  their  respective 

insertions,  splenius  capitis  and  splenius  colli. 

a.  The  splenius  capitis  is  inserted  into  the  mastoid  process, 
and  into  the  outer  part  of  the  superior  curved  line  of  the  occipital 
bone,  beneath  the  sterno-mastoid. 

6.  The  splenius  colli  is  inserted  by  tendinous  slips  into  the 
posterior  tubercles  of  the  transverse  processes  of  the  upper  three 
cervical  vertebrae.  The  splenius  is  supplied  by  the  posterior 
divisions  of  the  spinal  nerves. 

The  action  of  the  splenius,  taken  as  a  whole,  is  to  draw  the 
head  and  the  upper  cervical  vertebras  towards  its  own  side  :  so  far, 
it  eo -operates  with  the  opposite  sterno-mastoid  muscle.  When 
the  splenii  of  opposite  sides  contract,  they  extend  the  cervical 
portion  of  the  spine,  and  keep  the  head  erect.  The  permanent 
contraction  of  a  single  splenius  may  occasion  wry  neck.  It  is 
necessary  to  be  aware  of  this,  otherwise  one  might  suppose  the 
opposite  sterno-mastoid  to  be  affected,  considering  that  the  ap- 
pearance of  the  distortion  is  alike  in  either  case. 

The  splenius  and  serratus  posticus  inferior  are 
to  be  detached  from  their  origins.     After  reflect- 


236  MUSCLES    OF    THE    BACK. 

ing  the  lumbar  fascia  from  its  internal  attachment,  the  erector 
spinse  is  exposed. 

EEKCTOB  The  mass  of  muscle  which  occupies  the  vertebral 

SPIN*:.  groove  on  either  side  of  the  spine,  is,  collectively, 

called  erector  spince,  since  it  counteracts  the  tendency  of  the  trunk 
to  fall  forwards.  Observe  that  it  is  thickest  and  strongest  at  that 
part  of  the  spine  where  it  has  the  greatest  weight  to  support — 
namely,  in  the  lumbar,  region ;  and  that  its  thickness  gradually 
decreases  towards  the  top  of  the  spine. 

It  arises  by  tendinous  fibres  from  the  posterior  fifth  of  the 
crest  of  the  ilium,  the  lower  part  and  back  of  the  sacrum,  and 
the  spines  of  the  lumbar  vertebrae.  From  this  extensive  origin 
the  muscular  fibres  ascend,  at  first  as  a  single  mass.  Near  the 
last  rib,  this  mass  divides  into  two  ;  an  outer,  called  the  sacro- 
lumbalis ;  an  inner,  the  longissimus  dorsi.  These  two  portions 
should  be  followed  up  the  back :  and  there  is  no  difficulty  in 
doing  so,  because  the  division  is  indicated  by  a  longitudinal  groove, 
in  which  we  observe  the  cutaneous  branches  of  the  intercostal 
vessels  and  nerves. 

SACRO-  Tracing  the  sacro-lumbalis  upwards,  we  find 

LUMBALIS.  that  it  terminates  in  a  series  of  tendons  which  are 

{inserted  into  the  angles  of  the  six  lower  ribs. 

MUSCULUS  By   turning   outwards   the   sacro-lumbalis,  we 

ACCESSOBIUS.  observe  that  it  is  continued  upwards  under  the 

name  of  musculus  accesswius  ad  sacro-lumbalem.  This  arises 
by  a  series  of  tendons  from  the  angles  of  the  seven  or  eight  lower 
ribs,  internal  to  the  preceding,  and  is  inserted  into  the  angles  of 
the  five  or  six  upper  ribs. 

CEKYICALIS  This  is  the  cervical  continuation  of  the  mus- 

ASCENDENS.  culus  accessorius.      It  arises  by  tendinous  slips 

from  the  four  or  five  upper  ribs,  and  is  inserted  into  the  transverse 
processes  of  the  fourth,  fifth  and  sixth  cervical  vertebrae. 

LONGISSIMUS  The  longissimus  dorsi  (the  inner  portion  of  the 

•Doasi.  erector  spinae)  terminates  in  tendons  which  are 

inserted,  internally,  into  the  tubercles  *  at  the  root  of  the  transverse 
*  Called  '  anapophyses'  by  Professor  Owen. 


MUSCLES    OP    THE    BACK.  237 

processes  of  the  lumbar  vertebrae,  also  into  the  transverse  processes 
of  all  the  dorsal  vertebrae,  and,  externally,  into  the  greater  number 
of  the  ribs  (varying  from  eight  to  eleven)  between  their  tubercles 
and  angles,  and,  lower  down,  into  the  lumbar  fascia,  and  into  the 
transverse  processes  of -the  lumbar  vertebrae. 

TRANSVERSALS  This  is  the  cervical  continuation  of  the  longissi- 
COLIJ.  mus  dorsi.  It  arises  by  tendinous  slips  from  the 

transverse  processes  of  the  second,  third,  fourth,  fifth,  and  sixth 
dorsal  vertebrae,  and  is  inserted  into  the  posterior  tubercles  of  the 
transverse  processes  of  the  four  or  five  lower  cervical  vertebras 
except  the  last. 

TRACHELO-  This  muscle,  situated  on  the  inner  side  of  the 

MASTOID.  -preceding,  is  the  internal  continuation  of  the 

longissimus  dorsi  to  the  cranium.  It  arises  from  the  transverse 
processes  of  the  three  or  four  upper  dorsal,  and  the  articular  pro- 
cesses of  the  three  or  four  lower  cervical  vertebrae,  and  is  inserted 
by  a  flat  tendon  into  the  back  part  of  the  mastoid  process  beneath 
the  splenius.* 

*  Those  who  are- familiar  with  the  transcendental  nomenclature  of  the  vertebrate 
skeleton  will  understand  from  the  following  quotation  the  plan  upon  which  the 
muscles  of  the  back  are  arranged  : — 

'  The  muscles  of  the  back  are  either  longitudinal  or  oblique  :  that  is,  they  either 
pass  vertically  downwards  from  spinous  process  to  spinous  process,  from  diapophysis 
to  diapophysis,  from  rib  to  rib  (pleurapophyses),  &c.,  or  they  extend  obliquely  from 
diapophysis  to  spine,  or  from  diapophy&is  to  pleurapophysis,  &c. 

'  The  erector  spinse  is  composed  of  two  •  planes  of  longitudinal  fibres  aggregated 
together,  below,  to  form  one  mass  at  their  point  of  origin,  from  the  spines  and  pos- 
terior surface  of  the  sacrum,  from  the  sacro-iliac  ligament,  and  from  the  posterior 
third  of  the  iliac  crest.  It  divides  into  two  portions,  the  sacro-lumbalis  and  the 
lougissimus  dorsi. 

'  The  former,  arising  from  the  iliac  crest,  or  from  the  pleurapophysis  (rib)  of  the 
first  sacral  vertebra,  is  inserted  by  short  flat  tendons  into  (1)  the  apices  of  the  stunted 
lumbar  ribs,  close  to  the  tendinous  origins  of  the  transversalis  abdominis ;  (2)  the 
angles  of  the  eight  or  nine  inferior  dorsal  ribs  ;  (3)  it  is  inserted,  through  the  medium 
of  the  musculus  accessorius,  into  the  angles  of  the  remaining  superior  ribs,  and  into 
the  long  and  occasionally  distinct  pleurapophysial  element  of  the  seventh  cervical 
vertebra;  and  (4)  through  the  medium  of  the  cervicalis  ascendens,  into  the  pleur- 
apophysial elements  of  the  third,  fourth,  fifth,  and  sixth  cervical  vertebrae.  In  other 
words,  the  muscular  fibres  extend  from  rib  to  rib,  from  the  sacrum  to  the  third  cervical 
verttbra. 


238  MUSCLES    OP   THE   BACK. 

This  is  a  long  narrow  muscle,  situated  close  to 
SPINALIS  DOESI.        ,  .  „       ° 

the  spines  of  the  dorsal  vertebrae,  and  apparently 

a  part  of  the  longissimus  dorsi ;  it  is  by  some  considered  the  inner- 
most column  of  the  erector  spinae.  It  arises  by  tendinous  slips 
from  the  spines  of  the  two  lower  dorsal  and  two  upper  lumbar 
vertebrae,  and  is  inserted  by  little  tendons  into  the  spines  of  the 
six  or  eight  upper  dorsal  vertebra?. 

The  muscles  of  the  spine  hitherto  examined  are  all  longitudinal 
in  their  direction.  We  now  come  to  a  series  which  run  obliquely 
from  the  transverse  to  the  spinous  processes  of  the  vertebrae.  And 
first  of  the  complexes. 

This  powerful  muscle  arises-  from  the  transverse 

COMPLEXUS.  „       ,  1  1  J   AT. 

processes  ot  the  six  or  seven  upper  dorsal  and  the 
last  cervical  vertebrae,  also  from  the  articular  processes  of  four  or 
five  cervical  vertebrae.  It  is  inserted  between  the  two  curved 
lines  of  the  occiput,  .near  the  vertical  crest.  In  the  centre  of  the 
muscle  there  is  generally  a  tendinous  intersection.  The  muscle  is 
perforated  by  the  posterior  branches  of  the  second  (the  great  occi- 
pital), third,  and  fourth  cervical  nerves.  It  is  chiefly  supplied  by 
the  great  occipital  nerve.  Its  action  is  to  maintain  the  head 
erect. 

Cut  transversely  through  the  middle  of  the  complexus,  and 
reflect  it  to  see  the  arteria  cervicalis  profunda  (p.  69),  and  the 
posterior  branches  of  the  cervical  nerves. 

TRANSVEESO  This  is  the  mass  of  muscle  which  lies  in  the 

SPINALIS.  vertebral  groove  after  the  reflection  of  the  com- 

plexus and  the  erector  spinae.  It  consists  of  a  series  of  fibres 
which  extend  from  the  transverse  and  articular  processes  to  the 

'  The  longissimus  dorsi,  situated  nearer  the  spine  than  the  sacro-lumbalis,  is  in- 
serted (1)  into  the  metapophysial  spine  of  the  lumbar  diapophyses ;  (2)  into  the 
diapophyses  of  all  the  dorsal  vertebrae, .  near  the  origin  of  the  levatores  costarum ; 
(3)  through  the  medium  of  the  transversalis  colli  into  the  diapophyses  of  the  second, 
third,  fourth,  fifth,  and  sixth  cervical  vertebrae ;  and  (4)  through  the  medium  of  the 
trachelo-mastoid  into  the  mastoid  process,  or  the  only  element  of  a  transverse  process 
possessed  by  the  parietal  vertebra.  In  other  words,  its  fibres  extend  from  diapophysis 
to  diapophysis,  from  the  sacrum,  upwards,  to  the  parietal  vertebra.' — '  Homologies  of 
the  Human  Skelc  ton,'  by  H.  Coote,  p.  7& 


MUSCLES    OF    THE    BACK.  239 

spinous  processes  of  the  dorsal  and  cervical  vertebrae,  and  is  for 
convenience  divided  into  the  semispinalis  dor  si  and  semispinalis 
colli. 

a.  The  semispinalis  dorsi  arises  from  the  transverse  processes 
of  the  dorsal  vertebrge,  from  the  sixth  to  the  tenth,  and  is  inserted 
into  the  spines  of  the  four  upper  dorsal  and  the  two  or  three  lower 
cervical  vertebrae. 

6.  The  semispinalis  colli  lies  beneath  the  complexus  and  arises 
from  the  transverse  processes  of  the  five  or  six  upper  dorsal  ver- 
tebrge, and  the  articular  processes  of  the  four  lower  cervical,  and 
is  inserted  into  the  spines  of  the  axis  and  the  three  or  four 
succeeding  vertebrae,  that  into  the  axis  being  the  most  fleshy 
fasciculus. 

Now  reflect  part  of  the  semispinalis  dorsi  in  order  to  expose 
the  multifidus  spince.  This  may  be  considered  a  part  of  the 
preceding  muscle,  since  its  fixed  points  and  the  direction  of  its 
fibres  are  the  same.  It  consists  of  a  series  of  little  muscles  which 
extend  between  the  spines  and  transverse  processes  of  the  vertebras 
from  the  sacrum  to  the  second  cervical  vertebra.  Those  in  the 
lumbar  region  are  the  largest.  They  arise  by  tendinous  slips  from 
the  transverse  processes  in  the  sacral  and  dorsal  region,  and  from 
the  articular  processes  in  the  lumbar  and  cervical  region.  They 
all  ascend  obliquely,  and  are  inserted  into  the  spines  and  laminae 
of  all  the  vertebras  excepting  the  atlas.  It  should  be  observed 
that  their  fibres  are  not  of  uniform  length  j  some  extend  only  from 
vertebra  to  vertebra,  while  others  extend  between  one,  two,  or 
even  three  vertebrae. 

Beneath  the  multifidus  spinaa,  in  the  dorsal  region  of  the  spine 
onlyr  are  eleven  flat  muscles,  called  rotatores  spinee.  They  arise 
from  the  upper  part  of  the  transverse  processes,  and  are  inserted 
into  the  lower  border  of  the  laminae  of  the  vertebra  above.  These 
muscles  form  but  a  part  of  the  multifidus  spinas. 

The  action  of  the  preceding  muscles  is,  not  only  to  assist  in 
maintaining  the  trunk  erect,  but  to  incline  and  rotate  the  spine 
to  one  or  the  other  side.  They  are  all  supplied  by  the  posterior 
branches  of  the  spinal  nerves. 


240  MUSCLES    OP    THE    BACK. 

LEVATORES  These  small  muscles  arise  from  the  apices  of  the 

COSTAKUM.  transverse  processes  of  the  seventh  cervical  and 

the  eleven  upper  dorsal  vertebrae,  and  are  inserted  into  the  rib 
below.  The  direction  of  their  fibres  corresponds  with  that  of  the 
outer  layer  of  the  intercostal  muscles.  They  are  muscles  of  in- 
spiration. 

These    muscles  extend   between  the  spines  of 
INTEESPINALES.  . .  ,   ,  _,,  ,  . 

contiguous  vertebrae.     They  are  arranged  in  pairs, 

and  only  exist  in  those  parts  of  the  vertebral  column  which  are  the 
most  movable.  In  the  cervical  region  they  pass  between  the 
spines  of  the  six  lower  cervical  vertebrae.  In  the  dorsal  they  are 
found  between  the  spines  of  the  first  and  second,  and  between 
those  of  the  eleventh  and  twelfth  dorsal  vertebrae.  They  are  also 
found  more  or  less  distinctly  between  the  spines  of  the  lumbar 
vertebrae. 

INTERTRANS-  These  muscles  extend  between  the  transverse 

VERSALES.  processes  in  the  cervical  and  lumbar  regions.     In 

the  neck  they  are  arranged  in  pairs,  like  the  interspinales,  and  the 
corresponding  cervical  nerve  separates  one  from  the  other.  In  the 
lumbar  region  they  are  four  in  number,  and  are  arranged  also  in 
pairs. 

We  have  next  to  examine  the  muscles  concerned  in  the  move- 
ments of  the  head  upon  the  first  and  second  cervical  vertebrae. 
(Fig.  47.) 

KECTUS  CAPITIS  This  is  a  largely  developed  interspinal  muscle. 
POSTICUS  MAJOK.  It  arises  by  a  small  tendon  from  the  well-marked 
spine  of  the  second  cervical  vertebra,  and,  expanding  considerably, 
is  inserted  below  the  superior  curved  ridge  of  the  occipital  bone. 
These  recti  muscles,  as  they  ascend,  one  on  each  side,  to  their  in- 
sertions, diverge  and  leave  an  interval  between  them  in  which  are 
found  the  recti  capitis  postici  minores. 

KECTUS  CAPITIS  This  is  also  an  interspinal  muscle,  but  smaller 
POSTICUS  MINOR.  than  the  preceding.  Arising  from  the  posterior 
tubercle  of  the  first  vertebra,  it  expands  as  it  ascends,  and  is  in- 
serted into  the  occipital  bone  between  the  inferior  curved  ridge 
and  the  foramen  magnum.  The  action  of  the  two  preceding 


SUB-OCCIPITAL   TRIANGLE. 


241 


muscles  is  to  raise  the  head.  They  are  supplied  with  nerves  from 
the  posterior  branch  of  the  sub-occipital. 

OBLIQUUS  This  arises  from  the  spine  of  the  second  cer- 

INFERIOR.  vical  vertebra,  and  is  inserted  into  the  transverse 

process  of  the  first.  Its  action  is  to  rotate  the  first  upon  the 
second  vertebra :  in  other  words,  to  turn  the  head  round  to  the 
same  side.  It  is  supplied  with  a  nerve  by  the  great  occipital 

FIG.  47. 


DRAWING   FROM    NATURE    OF   THE    SUBOCCIPITAL   TRIANGLE. 

1  and  7.  Complexus.  2.  Kectus  cap.  posticus  minor.  3.  Rectus  cap.  posticns  major.  4.  Obliquus 
inferior.  5.  Sterno-mastotd.  6.  Semispinalis  colli.  8.  Obliquus  superior.  10.  Splenins. 
11.  Trachelo-mastoid.  12.  Great  occipital  nerve.  13.  Occipital  artery  giving  off  its  descending 
branch— the  princeps  cervicis.  14.  Suboccipital  nerve.  15.  Third  cervical  nerve  (posterior 
branch). 

(posterior  division  of  the  second  cervical)  which  curves  up  under 
its  lower  border. 

OBLIQUUS  This  muscle  arises  from  the  transverse  process 

SUPERIOR.  of  the  atlas,  and,  ascending  obliquely  inwards,  is 

inserted  in  the  interval  between  the  curved  ridges  of  the  occipital 
bone.     Its  action  is  to  draw  the  occiput  towards  the  spine. 

£ 


242  NERVES    OP   THE    BACK. 

STOOCCIPITAL  Observe  that  the  obliqui  (superior  and  inferior) 

TRIANGLE.  an(j  the  rectus  capitis  posticus  major  form  what 

is  called  the  suboccipital  triangle.  The  outer  side  is  formed 
by  the  obliquus  superior;  the  inner,  by  the  rectus  capitis  pos- 
ticus major ;  the  lower,  by  the  obliquus  inferior.  Within  this 
triangle  may  be  seen  the  arch  of  the  atlas,  and  the  vertebral  artery 
lying  in  a  groove  on  its  upper  surface.  Between  the  artery  and 
the  bone  appears  the  posterior  division  of  the  suboccipital  nerve, 
which  here  sends  branches  to  the  recti  postici,  the  obliqui,  and  the 
complexus :  that  is  to  say,  it  supplies  the  muscles  which  form  the 
triangle,  and  the  complexus  that  covers  it. 

EECTUS  CAPITIS         This  small  muscle  extends  between  the  trans- 
LATEKALTS.  verse  process  of  the  first  vertebra  and  the  eminen- 

tia  jugularis  of  the  occiput ;  but,  since  this  eminence  is  the  trans- 
verse process  of  the  occipital  vertebra,  the  muscle  should  be 
considered  as  an  intertransverse  one.  Its  nerve  comes  from  the 
anterior  division  of  the  sub-occipital. 

NERVES  OF  THE          The  posterior  branches  of  the    spinal    nerves 
BACK.  supply  the  muscles  and  skin  of  the  back.     They 

pass  backwards  between  the  transverse  processes  of  the  vertebrae, 
and  divide  into-  external  and  internal  branches.  The  general 
plan  upon  which  these  nerves  are  arranged  is  the  same  throughout 
the  whole  length  of  the  spine  ;  but  since  there  are  certain  peculi- 
arities deserving  of  notice  in  particular  situations,  we  must  examine 
each  region  separately. 

CERVICAL  The  posterior  division  of  the  first  cervical  nerve 

EEGION.  (the  suboccipital)  passes  between  the  arch  of  the 

atlas  and  the  vertebral  artery,  and  divides  into  branches  which 
supply  the  recti  and  obliqui  muscles  concerned  in  the  movement 
of  the  head.  It  also  sends  downwards  a  loop  to  communicate  with 
the  second  cervical  nerve.  It  sometimes  gives  off  a  cutaneous 
branch  which  accompanies  the  occipital  artery,  and  is  distributed 
to  the  skin  of  the  back  of  the  scalp. 

The  posterior  branch  (the  great  occipital)  of  the  second  cervical 
nerve  is  the  largest  of  the  series,  and  emerges  between  the  arches 
of  the  atlas  and  axis.  It  turns  upwards  beneath  the  inferior 


NEEVES    OP   THE    BACK.  243 

oblique  muscle,  passes  through  the  complexus,  and  runs  with  the 
occipital  artery  to  the  back  of  the  scalp. 

The  posterior  divisions  of  the  six  lower  cervical  nerves  divide 
into  external  and  internal  branches.  The  external  are  small,  and 
terminate  in  the  splenius,  and  the  continuation  of  the  erector 
spinse — viz.,  the  trachelo-mastoid,  the  transversalis  colli,  and  the 
cervicalis  ascendens.  The  internal,  by  far  the  larger^  proceed 
towards  the  spines  of  the  vertebrae ;  those  of  the  third,  fourth, 
and  fifth  lie  between  the  complexus  and  the  .semispinalis,*  and 
after  supplying  the  muscles  terminate  in*  the  skin ;  those  of-  the 
sixth,  seventh,  and  eighth  lie  between  the  semispinalis  and  the 
multifidus  spinse,  to  which  they  are  distributed. 

DORSAL  The  posterior  divisions  of  the  spinal  nerves  in 

REGION.  this  region  come  out  between  the  transverse  pro- 

cesses and  the  tendons  attached  to  them.  They  soon  divide  into 
external  and  internal  branches.  The  external  pass  obliquely  over 
the  levatores  costarum,  between  the  sacro-lumbalis  and  the  longis- 
simus  dorsi ;  and  successively  increase  in  size  from  above  down- 
wards. The  upper  six  terminate  in  the  erector  spinae  and  the 
levatores  costarum  ;  the  rest,  after  supplying  these .  muscles,  pass 
through  the  latissimus  dorsi,  and  become  the /cutaneous  nerves  of  the 
back.  The  internal  successively  decrease  in  size  from  above  down- 
wards. They  run  towards  the  spine  between  the  semispinalis  dorsi 
and  the  multifidus  spinae.  The  upper  six,  after  giving  branches  to 
the  muscles,  perforate  the  trapezius  and  become  cutaneous  nerves. 
The  lower  ones  terminate  in  the  muscles  of  the  vertebral  groove. 

LUMBAR  The  general  arrangement  of  the  nerves  in  this 

EEGION.  region  resembles  that  of  the  dorsal.     Their  exter- 

nal branches,  after  supplying  the  erector  spinse,  become  cutaneous 
and  terminate  in  the  skin  over  the  buttock.  The  internal  branches 
supply  the  multifidus  spinae. 

The  posterior  divisions  of  the  spinal  nerves  in 
SACKAL  REGION.  . 

this  region  are  small.     With  the  exception  of  the 

*  The  posterior  branches  of  the  second,  third,  and  fourth  nerves  are  generally  con- 
nected, beneath  the  complexus,  by  branches  in  the  form  of  loops.  This  constitutes  the 
posterior  cervical  plexus  of  some  anatomists. 

K  2 


244  PE^EVEETEBEAL   MUSCLES. 

last,  they  come  out  of  the  spinal  canal  through  the  foramina  in 
the  back  of  the  sacrum.  The  upper  two  or  three  divide  into 
external  and  internal  branches.  The  internal  terminate  in  the 
multifidus  spinae ;  the  external  become  cutaneous  and  supply  the 
skin  of  the  gluteal  region.  The  last  two  sacral  nerves  proceed, 
without  dividing,  to  the  integument. 

The  coccygeal  nerve  is  exceedingly  small,  and,  after  joining  a 
small  branch  from  the  last  sacral,  terminates  in  the  skin.* 

ARTERIES  OF  The  arteries  which  supply  the  back  are: — 1. 

THE  BACK.  Small    branches    from    the   occipital;    2.  Small 

branches  from  the  vertebral ;  3.  The  deep  cervical ;  4.  The  pos- 
terior branches  of  the  intercostal  and  lumbar  arteries. 

The  occipital  artery  furnishes  several  small  branches  to  the 
muscles  at  tbe  back  of  the  neck ;  one,  larger  than  the  rest,  the 
arteria  princeps  cerv  ids,  descends  beneath 'the  complexus,  and 
generally  inosculates  with  the. deep- cervical  -artery,  and  with  small 
branches  from  the  vertebral. 

The  vertebral  artery  runs  along  the  groove  in  the  arch  of  the 
atlas,  and,  before  perforating  the  posterior  occipito-atlantoid  liga- 
ment to  enter  the  skull,  distributes  small  branches  to  the  adjacent 
muscles. 

The  deep  cervical  artery  is  the  posterior  branch  of  the  first 
intercostal  artery  (from  the  subclavian).  It  passes  backwards 
between  the  transverse  >  process  of  the  last  cervical  vertebra  and 
the  first  rib :  it  then  ascends  between  the  complexus  and  the 
semispinalis  colli,  and  anastomoses  with  the  princeps  cervicis. 

The  posterior  branches  of  the  intercostal  and  lumbar  arteries 
accompany  the  corresponding  nerves,  and  are- in  all  respects  similar 
to  them  in  distribution.  Each  sends  a  small  branch  into  the 
spinal  canal  (intraspinal),  and  small  branches  to  the  vertebra. 

The  veins  correspond  to  the  arteries. 

PR;E-VERTEBHAL         We   have,   lastly,   to   examine    three   muscles 
MUSCLES.  situated  in  front  of  the  spine :  namely,  the  longus 

colli,  the  rectus  capitis   anticus   major,  and   the   rectus   capitis 

*  The  branching  of  the  posterior  divisions  of  the  several  spinal  nerves  has  been 
accurately  described  by  Ellis,  'Med.  Gazette,'  Feb.  10,  1813. 


PE^EVEETEBBAL   MUSCLES.  245 

anticus  minor.  In  order  to  have  a  complete  view  of  the  two  latter, 
a  special  dissection  should  be  made,  before  the  head  is  removed 
from  the  first  vertebra. 

This  muscle  is  situated  in  front  of  the  spine, 
and  extends  from  the  third  dorsal  to  the  first 
cervical  vertebra.  For  convenience  of  description  it  is  divided 
into  three  sets  of  fibres,  of  which  one  extends  longitudinally  from 
the  body  of  one  vertebra  to  that  of  another ;  the  two  others  extend 
obliquely  between  the  transverse  processes  and  the  bodies  of  the 
vertebrae. 

The  longitudinal  portion  of  the  muscle  arises  from  the  bodies 
of  the  two  or  three  upper  dorsal  and ^ the  three  lower  cervical 
vertebras,  and  is  inserted  into  the  bodies  of  the  second*,  third  and 
fourth  cervical  vertebras. 

The  superior  oblique  portion,  arising  from  the  anterior 
tubercles  of  the  transverse  processes  of  the  third,  fourth,  and 
fifth  cervical  vertebra?,  ascends  inwards,  and  is  inserted  into 
the  front  part  or  body  of  the  first  cervical  vertebra.  The  in- 
ferior oblique  portion  proceeds  from  the  bodies  of  the  three 
upper  dorsal  vertebras,  and  is  inserted  into  the  transverse  pro- 
cesses of  the  fifth  and  sixth  cervical  vertebras.  The  action  of 
this  muscle,  taken  as  a  whole,  must  be  to  bend  the  cervical  region 
of  the  spine.  Its  nerves  come  from,. the  cervical  and  brachial 
plexuses. 

EECTUS  CAPITIS  This  muscle  arises  from  the  anterior  tubercles 
ANTICUS  MAJOH.  of  the  transverse  processes  of  the  third,  fourth, 
fifth,  and  sixth  cervical  vertebras,  and  is  inserted  into  the 
basilar  process  of  the  occipital  bone,  in  front  of  the  foramen 
magnum. 

EECTUS  CAPITIS  This  muscle  arises*  from  the  root  of  the  trans- 
ANTICUS  MINOB.  verse  process  of  the  first  cervical  vertebra,  and  is 
inserted  into  the  basilar  process  of  the  occipital  bone,  nearer  to 
the  foramen  magnum  than  the  preceding  muscle.  The  action 
of  the  recti  muscles  is  to  bend  the  head  forwards.  They  are 
supplied  with  nerves  from  the  anterior  division  of  the  sub- 
occipital. 


246  LIGAMENTS   OP   THE    SPINE. 

LIGAMENTS   OF   THE  SPINE. 

The  vertebrae  are  connected  by  their  intervertebral  fibro-carti- 
lages,  by  ligaments  in  front  of  and  behind  their  bodies,  and  by 
ligaments  which  extend  between  their  arches  and  their  spines. 
Their  articular  processes  have  capsular  ligaments,  and  synovia! 
membranes. 

ANTERIOR  COM-  This  is  a  strong  band  of  longitudinal  fibres 
MON  LIGAMENT.  which  extends  along  the  front  of  the  bodies  of  the 
vertebrae  from  the  axis  to  the  sacrum.  The  fibres  are  not  all  of 
equal  length.  The  more  superficial  extend  from  one  vertebra  to 
the  fourth  or  fifth  below  it ;  those  a  little  deeper  pass  from  one 
vertebra  to  the  second  or  third  below  it ;  while  the  deepest  of  all 
preceed  from  vertebra  to  vertebra.  The  ligament  becomes  broader 
and  stronger  in  proportion  to  the  size  of  the  vertebrae.  By  making 
transverse  incisions  through  it  in  different  situations,  we  observe 
that  its  fibres  are  more  firmly  adherent  to  the  intervertebral 
cartilages,  and  to  the  borders  of  the  vertebrae,  than  to  the  middle 
of  the  bones. 

POSTEEIOR  COM-  This  extends  longitudinally,  in  a  similar  manner 
MON  LIGAMENT.  to  the  anterior  common  ligament,  along  the 
posterior  surface  of  the  bodies  of  the  vertebrae,  from  the  axis  to 
the  sacrum,  and  sends  up  a  prolongation  to  the  anterior  border 
of  the  foramen  magnum  continuous  with  the  apparatus  liga- 
mentosus. 

INTERSPINOTTS  These  bands  of  ligamentous  fibres  fill  up  the 

LIGAMENTS.  intervals  between  the  spines  of  the   dorsal  and 

lumbar  vertebrae.  They  are  the  most  marked  in  the  lumbar 
region.  Those  fibres  which  connect  the  apices  of  the  spines, 
being  stronger  than  the  rest,  are  described  as  separate  ligaments 
under  the  name  of  supra-spinous.  Their  use  is  to  limit  the 
flexion  of  the  spine. 

LIGAMENTS  These  are  called,  on  account  of  their  colour, 

BETWEEN  THE  Ugamenta    sub/lava. — To    obtain    a   good   view 

ARCHES  OF  THE         of  them,  the  arches  of  the  vertebrae  should   be 

removed  with  a  saw.       They  pass   between  the 


LIGAMENTS    OP    THE    SPINE.  247 

arches  of  the  contiguous  vertebrae,  from  the  axis  to  the  sacrum ; 
none  existing  between  the  occiput  and  the  atlas,  or  between  the 
atlas  and  axis.  They  are  composed  of  yellow  elastic  tissue,  the 
fibres  being  arranged  vertically,  and  their  strength  increases  with 
the  size  of  the  vertebrae.  This  elasticity  answers  a  double  pur- 
pose :  it  not  only  permits  the  spine  to  bend  forwards,  but  materi- 
ally assists  in  restoring  it  to  its  curve  of  rest.  They  economise 
muscular  force,  like  the  Ugamentum  nuchae  in  animals. 

INTKEVERTE-  This  substance,  placed  between  the  bodies  of 

BRAL  FIBEO-  the  vertebrae,  is  by  far  the  strongest  bond  of  con- 

nection between  them,  and  fulfils  most  important 
purposes  in  the  mechanism  of  the  spine.  Its  peculiar  structure  is 
adapted  to  break  shocks,  and  to  render  the  spine  flexible  and 
resilient.  To  see  the  structure  of  an  intervertebral  fibro-cartilage, 
a  horizontal  section  must  be  made  through  it.  It  is  firm  and 
resisting  near  the  circumference,  but  soft  and  pulpy  towards  the 
centre.  The  circumferential  portion  is  composed  of  concentric 
layers  of  fibro-cartilage,  placed  vertically.  These  layers  are 
attached  by  their  edges  to  the  vertebrae ;  they  gradually  decrease 
in  number  from  the  circumference  towards  the  centre,  and  the 
interstices  between  them  are  filled  by  soft  pulpy  tissue.  The 
central  portion  is  composed  almost  entirely  of  this  pulpy  tissue; 
and  it  bulges  when  no  longer  under  pressure.  Thus  the  bodies 
of  the  vertebrae,  in  their  motions  upon  each  other,  revolve  upon 
an  elastic  cushion  tightly  girt  all  round  by  bands  of  fibrous  tissue. 
These  motions  are  regulated  by  the  articular  processes. 

Dissect  an  intervertebral  substance  layer  after  layer  in  front, 
and  you  will  find  that  the  circumferential  fibres  extend  obliquely 
between  the  vertebrae,  crossing  each  other  like  the  branches  of  the 
letter  X. 

The  thickness  of  the  intervertebral  cartilages  is  not  the  same 
in  front  and  behind.  It  is  this  difference  in  their  thickness,  more 
than  that  in  the  bodies  of  the  v-ertebrae,  which  produces  the  several 
curves  of  the.  spine.  In  the  lumbar  and  cervical  regions  they  are 
thicker  in  front ;  in  the  dorsal  region,  behind. 

The  structure  of  the  intervertebral  cartilages  explains  the  well-known 


248  LIGAMENTS    OF   THE    SPINE. 

fact  that  a  man  becomes  shorter  after  standing  for  some  hours ;  and  that 
he  regains  his  usual  height  after  rest.  The  difference  between  the  morn- 
ing and  evening  stature  amounts  to  more  than  half  an  inch. 

It  also  explains  the  fact  that  a  permanent  lateral  curvature  of  the 
spine  may  be  produced  (especially  in  the  young)  by  the  habitual  practice 
of  leaning  to  this  or  that  side.  Experience  proves  that  the  cause  of  late- 
ral curvature  depends  more  frequently  upon  some  alteration  in  the  struc- 
ture of  the  fibro-cartilages  than  upon  the  bones.  From  an  examination 
of  the  bodies  of  one  hundred  and  thirty-four  individuals  with  crooked 
spines,  it  was  concluded  that,  in  two-thirds,  the  bones  were  perfectly 
healthy  ;  that  the  most  frequent  cause  of  curvature  resided  in  the  inver- 
tebral  substances,  these  being,  on  the  concave  side  of  the  curve,  almost 
absorbed,  and,  on  the  convex  side,  preternaturally  developed.  As  might 
be  expected  in  these  cases,  the  muscles  on  the  convex  side  become 
lengthened,  and  degenerate  in  structure.* 

LIGIAMENTUM  This  ligament  is  a  thin  fibrous  septum  inter- 

NUCHJE.  mingled  with  elastic  tissue,  which  extends  from 

the  spinous  processes  of  the  six  lower  cervical  vertebrae  to  the 
external  occipital  protuberance.  It  forms  an  intermuscular  septum 
down  the  back  of  the  neck,  and  may  be  regarded  as  the  continua- 
tion upwards  of  the  supra-spinous  ligament. 

CAPSULAB  Each  joint  between  the  articular  processes  has 

LIGAMENTS.  a  capsular  ligament  and  a  synovial  membrane. 

The  surfaces  of  the  bones  are  crusted  with  cartilage. 

INTEBTBANS-  These  are  thin  bands  of  fibres  which  pass  be- 

VERSE  LIGAMENTS,  tween  the  transverse  processes  of  the  vertebrae. 
They  are  rudimentary  in  the  cervical  region,  and  are  sometimes 
absent. 

MOVEMENTS  OF  Though  but  little  movement  is  permitted  be- 
THE  SPINE.  tween  any  two  vertebrae  (the  atlas  and  axis  ex- 

cepted),  yet  the  collective  motion  between  them  all  is  considerable. 
The  spine  can  be  bent  forwards,  backwards,  or  on  either  side ;  it 
also  admits  of  slight  rotation.  In  consequence  of  the  elasticity 
of  the  intervertebral  cartilages  and  the  ligamenta  subflava,  it 
returns  spontaneously  to  its  natural  curve  of  rest  like  an  elastic 
bow.  Its  mobility  is  greatest  in  the  cervical  region,  on  account  of 

*  On  this  subject  see  '  Hildebrandt's  Anatomic,'  B.  ii.  s.  155. 


LIGAMENTS    OF    THE    SPINE.  249 

the  thickness  of  the  fibro-cartilages,  the  small  size  of  the  vertebrae, 
the  oblique  direction  of  their  articulations,  and,  above  all,  trhe 
horizontal  position  and  the  shortness  of  their  spines.  In  the 
dorsal  region  there  is  very  little  mobility,  on  account  of  the 
vertical  direction  of  the  articular  processes,  and  the  manner  in 
which  the  arches  and  the  spines  overlap  each  other.  In  the 
lumbar  region,  the  spine  again  becomes  more  movable,  on  account 
of  the  thickness  of  the  intervertebral  cartilages,  and  the  horizontal 
direction  of  the  spinous  processes. 

LIGAMENTS  BB-  ^ne  °cciput  is  connected  to  the  atlas  by  an 
TWEBN  THE  Occi-  anterior  occipito-atlantoid  ligament  which  passes 
PITAL  BONE  AND  from  the  foramen  magnum  to  the  front  arch  of 

IE    TLAS.  ^e   a£iag<     rpj^  thickest  part  of  this  is  in  the 

middle.  A  posterior  occipito-atlantoid  ligament  extends  in  a 
similar  manner  from  the  posterior  border  of  the  foramen  magnum 
to  the  posterior  arch  of  the  atlas.  It  is  thin  and,  superiorly,  be- 
comes blended  with  the  dura  mater,  and  is  pierced  by  the  vertebral 
artery  and  the  suboccipital  nerve.  Between  the  condyles  of  the 
occipital  bone  and  the  atlas,  there  is  on  each  side  a  capsular 
ligament. 

The  movements  which  take  place  between  the  occipital  bone 
and  the  atlas  are  flexion  and  extension,  as  in  nodding  forwards 
and  backwards ;  and  lateral  movement,  as  in  inclining  the  head 
sideways. 

LIGAMENTS  These  are  the  most  important ;  and  to  see  them, 

BETWEEN  THE  the  spinal  canal  must  be  exposed  by  removing  the 

OCCIPITAL  BONE  arches  of  the  upper  cervical  vertebrae,  and  the 
posterior  common  ligament,  which  is  here  very 
thick  and  strong.  It  descends  from  the  basilar  process  of  the 
occipital  bone  over  the  odontoid  and  transverse  ligaments,  and  is 
called  the  occipito-axoid  ligament  or  the  apparatus  liga- 
mentosus  colli. 

ODONTOID  ou  The  odontoid  or  check  ligaments  (fig.  48)  are 

CHECK  LIGAMENTS,  two  very  strong  ligaments  which  proceed  from 
the  sides  of  the  odontoid  process  to  the  tubercles  on  the  inner 
sides  of  the  condyles  of  the  occiput.  Their  use  is  to  limit  the 


250 


LIGAMENTS    OP    THE    SPINE. 


rotation  of  the  head.  A  third  or  middle  odontoid  ligament  passes 
from  the  apex  of  the  odontoid  process  to  the  margin  of  the 
foramen  magnum.  It  is  sometimes  called  the  ligamentum  sus- 
pensorium. 

The  odontoid  process  of  the  axis  forms  a  pivot 
upon  which  the  head  and  atlas  rotate.     The  most 
important  ligament  is  the  transverse  (fig.  48).    It 
passes  behind  the  odontoid  process,  and  is  attached 
to  the  tubercles  on  the  inner  sides  of  the  articular  processes  of  the 

-  FIG.  48. 


ARTICULATION 
BETWEEN  THE 
ATLAS  AND  THE 
Axis. 


POST?  COMMON    LICT 


DIAGRAM    OF   THE    ODONTOID    AND    TRANSVERSE' LIGAMENTS. 

atlas.  From  the  cerftre  of  this  ligament  a  few  fibres  pass  upwards, 
to  be  attached  to  the  basilar  process,  and  some  downwards  to  the 
body  of  the  axis,  giving,  it  a  cruciform  appearance.  Thus  it  forms 
with  the  atlas  a  ring,  into  which  the  odontoid  process  is  received. 
If  this  transverse  ligament  be  divided,  we  observe  that  the  odon- 
toid process  is  covered  with  cartilage  in  front  and  behind,  and  is 
provided  with  two  synovial  membranes. 

The  anterior  arch  of  the  atlas  is  connected  to  the  body  of  the 
axis  by  the  anterior  atlanto-axoid  ligament ;  posteriorly,  the  two 
arches  are  connected  by  the  posterior  atlanto-axoid  ligament. 


LIGAMENTS    OF    THE    RIBS.  251 

ARTICULATION-  All  the  ribs,  with  the  exception  of  the  first  and 

OF  THE  EIBS.  the  two  last,  are  articulated  with  the  bodies  of  two 

vertebrae,  and  with  -the  transverse  processes  (fig.  49). 

The  headof  each  rib  presents  two  articular  surfaces,  correspond- 
ing- to  the  bodies  of  two  vertebrae.  There  are  two  distinct  articu- 
lations, each  provided  with  a  separate  synovial  membrane.  The 
ligaments  are  : — 1.  An  anterior,  which  connects  the  head  of  the 
rib  with  the  vertebras,  .and  with  the  intervening  fibro-cartilage : 
this,  on  account  of  the  divergence  of .  its  fibres,  is  called  the  stel- 
late ligament  (fig.  50).  2. .,  An  intern-articular,  ..which  proceeds 
from  the  head  of  the  rib  to  the  intervertebral  cartilage. 

FIG.  49. 


DIAGRAM    SHOWING    THE    LIGAMENTS    CONNECTING    THE    RIB   WITH    THE    VERTEBRA. 

1.  The  anterior  costo-central  ligament.  3.  The  posterior  costo-transverse  ligament. 

2.  The  interosseous,  or  middle  costo-transverse    .  4.  The  synovial  membrane  between  the  rib  and 

ligament.  the  body  of  the  vertebra. 

The  tubercle  of  the  rib  articulates  with  the  transverse  process. 
This  articulation  has  a  capsular  and  synovial  membrane,  and  is 
secured  by  the  following  ligaments: — 1.  The  posterior  costo- 
transverse  passes  from  the  apex  of  the  transverse  process  to  the 
summit  of  the  tubercle  of  the  rib.  2.  The  middle  costo-trans- 
verse connects  the  neck  of  the  rib  to  the  front  surface  of  the 
transverse  process.  3.  The  superior  costo-transverse  ascends  from 
the  neck  of  the  rib  to  the  lower  border  of  the  transverse  process 
above  it  (fig.  50). 


252  ARTICULATION    OP   THE    LOWER  JAW. 

The  head  of  the  first  rib  articulates  with  a  single  vertebra. 
The  eleventh  and ,  twelfth  ribs  articulate  each  with  a  single 
vertebra,  and  are  not  connected  to  the  transverse  processes. 

The  cartilages  of  all  the  true  ribs  are  received 
CONNECTION 

BETWEEN  THE  in^o  slight  concavities  on  the  side  of  the  sternum, 

CARTILAGES  OF  aiad  are  secured  by  anterior^  posterior,  upper  and 
THE  RIBS  AND  THE  iower  ligaments.  There  is  a  synovial  membrane 
between  the  cartilage  of  each  rib  and  the  sternum, 
except  that  of  the  first,  and  usually  at  each  articulation  the  synovial 
membrane  is  separated  into  two  by  an  inter-articular  ligament. 


m.       ^fS^&rn — ^BW"*n  imfff 
I.  1.  1.    Superior    costo-       %*=*5*^     W_^«       w-   t  „',  /  2. 2. 2.  Anterior  costo-cen- 

transverse  ligaments.  ^^-X'lvSr  M  BH     "^JOA  *ra^ or  stellate  ligaments. 


COSTO-VERTEBEAT,   LIGAMENTS. 


The  cosiai  cartilages  from  the  sixth  to  the  tenth  are  connected 
by  ligamentous  fibres. 

ARTICULATION  ^ne  condyle  of  the  lower  jaw  articulates  with 

or  THE  LOWER         the  glenoid  cavity  of  the  temporal  bone.     The 
JAW-  joint   is  provided  with   an  inter-articular  fibro- 

cartilage,  with  external  and  internal  lateral  ligaments,  and  two 
synovial  membranes  (fig.  51). 

The  external  lateral  ligament  extends  from  the  zygoma  and  its 
tubercle ;  its  fibres  pass  downwards  and  backwards  to  the  tubercle 
of  the  condyle  of  the  jaw. 

The  internal  lateral  ligament  extends  from  the  spinous  process 
of  the  sphenoid  bone  to  the  border  of  the  dental  foramen.  This 
so-called  ligament  cannot  in  any  way  contribute  to  the  strength  of 


ARTICULATION    OP   THE    LOWER   JAW. 


253 


the  joint :  the  articulation  of  one  side  performs  the  office  of  inter- 
nal lateral  ligament  to  the  other. 

The  inter-articular  fibro-vartilage  is  a  thin  plate  of  an  oval 
form,  and  thicker  at  the  margin  than  at  the -centre.  It  is  connected 
on  the  outer  side  to  the  external  lateral  ligament,  and  on  the  inner 
side  some  of  the  fibres  of  the  external  pterygoid  muscle  are  in- 
serted into  it. 

FIG. -51. 


Section  through  the  gtenoid  cavity 
Inter- articular  fibro- cartilage  , 

Internal  lateral  ligament     .    .  ,.— 


TRANSVERSE  SECTION  TO  SHOW  THE  LIGAMENTS  AND  THE  FIBRO- CARTILAGE  OF  THE 
JOINT  OF  THE  LOWER  JAW.  THE  DOTTED  LINES  REPRESENT  THE  TWO  STNOVIAL 
MEMBRANES. 

There  are  two  synovial  membranes,  an  upper  and  a  lower,  for 
the  joint.  The  larger  and  looser  of  the  two  is  situated  between 
the  glenoid  cavity  and  the  fibre-cartilage.  The  lower  is  interposed 
between  the  fibro- cartilage  and  the  condyle  of  the  jaw.  They 
sometimes  communicate  through  a  small  aperture  in  the  centre  of 
the  fibro-cartilage. 

The  form  of  the  articulation  of  the  lower  jaw  admits  of  move- 
ment, upwards  and  downwards,  forwards,  backwards,  and  from  side 


254  ABTICULATION   OP   THE    LOWER  JAW. 

to  side.  A  combination  of  these  movements  takes  place  in  masti- 
cation :  during  this  act  the  condyles  of  the  jaw  describe  an  oblique 
rotatory  movement  in  the  glenoid  cavity.  The  purposes  served  by 
the  nbro-cartilage  in  this  joint  are  : — first,  it  follows  the  condyle, 
and  interposes  a  convenient  socket  for  all  its  movements :  second, 
being  elastic,  it  breaks  shocks  •;  for  shocks  here  would  be  almost 
fatal,  considering  what  a  thin  plate  of  bone  the  glenoid  cavity  is, 
and  that  just  above  it  is  the  brain. 


255 


DISSECTION  OF  THE   UPPER  EXTREMITY. 

THE  arm  being  placed  at  right  angles  with  the 
trunk,  and  slightly  rotated  outwards,  make  three 
incisions  through  the  skin  :  the  first,  along  the  middle  of  the 
sternum ;  the  second,  along  the  lower  border  of  the  clavicle  and 
down  the  front  of  the  upper  arm  for  about  four  inches  ;  the  third, 
from  the  ensiform  cartilage,  backwards,  to  the  posterior  border  of 
the  axilla. 

The  skin  should  be  carefully  dissected  from  the  subjacent  layer 
of  subcutaneous  fascia  and  fat.  In  doing  so  notice  the  thin  fibres 
of  the  broad  subcutaneous  muscle  of  the  neck,  tplatysma  myoides' 
(p.  17). 

CUTAKEOUS  The  numerous  nerves  which  run  through  the 

NEBVES.  subcutaneous  tissue  to  the    skin  and  mammary 

gland  must  be  carefully  dissected  out.  They  are  derived  from 
various  sources :  some,  branches  of  the  superficial  cervical  plexus, 
descend  over  the  clavicle;  others,  branches  of  the  intercostal 
nerves,  come  through  the  intercostal  spaces  close  to  the  sternum, 
each  with  a  small  artery  ;  a  third  series,  also  branches  of  the  inter- 
costal nerves,  come  out  on  the  side  of  the  chest,  and  run  forwards 
over  the  outer  border  of  the  pectoralis  major. 

The  supra-clavicular  nerves,  which  descend  over  the  clavicle, 
are  subdivided,  according  to  their  direction,  into  sternal,  cla- 
vicular, and  acromial  branches  (diagram,  p.  19).  The  sternal 
cross  the  inner  end  of  the  clavicle  to  supply  the  skin  over  the 
upper  part  of  the  sternum.  The  clavicular  pass  over  the  middle 
of  the  clavicle,  and  supply  the  integument  over  the  front  of  the 
chest  and  the  mammary  gland.  The  acromial  branches  cross 
over  the  outer  end  of  the  clavicle,  and  distribute  their  filaments  to 
the  skin  of  the  shoulder. 


256  PECTORALIS   MAJOR. 

Near  the  sternum  are  found  the  anterior  cutaneous  branches 
or  terminal  filaments  of  the  intercostal  nerves.  After  piercing 
the  pectoralis  major,  each  nerve  sends  an  inner  filament  to  the 
skin  over  the  sternum,  and  an  outer  larger  one,  which  supplies  the 
skin  over  the  pectoral  muscle.  That  of  the  3d  and  4th  inter- 
costal supplies  also  the  mammary  gland. 

Branches  of  the  internal  mammary  artery,  for  the  supply  of 
the  mammary  gland,  accompany  these  nerves.  During  lactation 
they  increase  in  size,  ramifying  tortuously  over  the  surface  of 
the  gland.  They  are  occasionally  as  large  as  the  radial  at  the 
wrist. 

The  lateral  cutaneous  branches  of  the  intercostal  nerves  come 
out  between  the  digitations  of  the  serratus  magnus  on  the  side  of 
the  chest,  and  divide  into  anterior  and  posterior  branches.  The 
anterior  branches  curve  round  the  free  border  of  the  pectoralis 
major  and  then  supply  the  skin  over  that  muscle  and  the  mamma. 
The  posterior  branches  supply  the  skin  of  the  back  of  the  chest. 

Dissect  off  the  superficial  fascia  and  fat  with 
the  mammary  gland.  Thus  you  will  expose  the 
strong  deep  fascia  which  is  closely  attached  to  the  pectoralis  major 
and  deltoid  muscles.  It  is  continuous,  above,  with  the  fascia  of 
the  neck ;  below,  with  that  of  the  arm.  At  the  axilla  it  becomes 
denser,  where  it  passes  from  the  pectoral  to  the  latissimus  dorsi 
muscles. 

Reflect  this  fascia  from  the  pectoralis  major  by  dissecting 
parallel  with  the  course  of  its  fibres.  The  muscle  having  been 
fully  exposed,  observe  its  shape,  the  course  of  its  fibres,  their  origin 
and  insertion.* 

PECTORALS  The  pectoralis  major  is   the   large  triangular 

MAJOB.  muscle  in  the  front  of  the  chest.     It  arises  from 

the  sternal  half  of  the  clavicle,  from  the  front  of  the  sternum, 
from  the  cartilages  of  all  the  true  ribs  except  the  first  and  the  last, 

*  Sometimes  we  find  a  thin  little  muscle  running  perpendicularly  in  front  of  the 
inner  part  of  the  pectoralis  major.  This  is  the  rectus  sternalis  or  sternalis  brutorum. 
It  arises  inferiorly  by  a  tendinous  expansion  from  the  rectus  abdominis,  and  is  con- 
nected above  to  the  tendon  of  the  sterno-mastoid. 


PECTOEALIS    MAJOE.  257 

and  from  the  aponeurosis  of  the  external  oblique  muscle  of  the 
abdomen.  The  fibres  converge  towards  the  arm,  and  terminate 
in  a  flat  tendon,  about  two  inches  in  breadth,  which  is  inserted 
into  the  anterior  margin  of  the  bicipital  groove  of  the  humerus. 
The  arrangement  of  its  fibres,  as  well  as  the  structure  of  its  tendon, 
is  peculiar.  The  lower  fibres,  which  form  the  boundary  of  the  axilla, 
are  folded  beneath  the  rest,  and  terminate  upon  the  upper  part  of 
the  tendon — i.e.  nearer  to  the  shoulder  joint ;  the  upper  fibres, 
which  arise  from  the  clavicle,  and  are  frequently  separated  from 
the  main  body  of  the  muscle  by  a  slight  interval,  descend  in  front  of 
the  lower,  and  terminate  upon  the  lower  part  of  the  tendon.  Con- 
sequently the  upper  and  lower  fibres  of  the  muscle  cross  each  other 
previously  to  their  insertion. 

The  object  of  this  arrangement  is  to  enable  all  the  fibres  to  act 
simultaneously  when  the  arm  is  extended. 

The  upper  part  of  the  tendon  sends  off  a  fibrous  prolongation, 
which  binds  down  the  long  head  of  the  biceps,  and  is  attached  to 
the  great  tuberosity  of  the  humerus  :  another  tendinous  expansion 
is  prolonged  backwards  to  the  tendon  of  the  deltoid  muscle ;  and 
a  third  passes  downwards  to  be  intimately  connected  with  the  fascia 
of  the  upper  arm. 

The  chief  action  of  the  pectoralis  major  is  to  draw  the  humerus 
towards  the  chest :  as  in  placing  the  hand  on  the  opposite  shoulder, 
or  in  pulling  an  object  towards  the  body.  When  the  arm  is  raised 
and  made  the  fixed  point,  the  muscle  assists  in  raising  the  trunk, 
as  in  climbing.  Thus  too,  on  emergency,  it  can  act  as  an  auxiliary 
muscle  of  inspiration. 

Between  the  pectoralis  major  and  the  deltoid,  the  great  muscle 
covering  the  shoulder,  is  an  interval  varying  in  extent  in  different 
subjects,  but  always  more  marked  towards  the  clavicle.  It  contains 
a  small  artery — the  thoracica  humeraria — and  the  cephalic  vein, 
which  ascends  on  the  outer  side  of  the  arm,  and  empties  itself 
into  the  axillary.  This  interval  is  the  proper  place  to  feel  for  the 
coracoid  process.  In  doubtful  injuries  about  the  shoulder,  this 
point  of  bone  is  a  good  landmark  in  helping  the  surgeon  to  arrive 
at  a  correct  diagnosis. 

8 


258  INFRA-CLAVICULAR   REGION. 

The  pectoralis  major  is  supplied  with  nerves  by  the  anterior 
thoracic  branches  of  the  brachial  plexus ;  with  blood,  by  the  long 
and  short  thoracic  branches  of  the  axillary  artery. 

DISSECTION  Eeflect  the  clavicular  part  of  the  pectoralis 

ANATOMY  OF  THE  major,  and  in  doing  so,  notice  a  small  nerve,  the 
INFBA-CLAVICULAR  external  anterior  thoracic,  which  enters  the  under 
surface  of  this  part  of  the  muscle.  Beneath  the 
portion  thus  reflected,  part  of  the  pectoralis  minor  will  be  exposed. 
In  this  triangle,  bounded,  above,  by  the  clavicle,  below,  by  the 
upper  border  of  the  sternal  origin  of  the  pectoralis  major,  and,  on 
the  outer  side,  by  the  deltoid,  is  an  important  space  in  which  the 
relative  position  of  the  following  objects  must  be  carefully  ex- 
amined : — 

COSTO-CORACOID  a.  A  strong  ligamentous  expansion,  called  the 
MEMBRANE.  costo-coracoid  membrane  extends  from  the  car- 

tilage of  the  first  rib  to  the  coracoid  process.  Between  these 
points  it  is  attached  to  the  clavicle,  and  forms  a  complete  invest- 
ment for  the  subclavius  muscle.  Its  crescent-shaped  edge  arches 
over,  and  protects  the  axillary  vessels  and  nerves;  from  this  edge 
is  prolonged  a  funnel-shaped  fascia,  which  covers  the  axillary 
vessels,  forming  the  anterior  portion  of  their  sheath ;  the  pos- 
terior being  formed  by  a  prolongation  of  the  deep  cervical  fascia. 
The  front  portion  of  this  sheath  is  perforated  by  the -cephalic  vein, 
the  thoracica  acromialis  artery,  and  the  anterior  thoracic  nerves. 
This  fascia  must  be  removed. 

b.  The  subclavius  muscle  enclosed  in  its  fibrous  sheath. 

c.  The  axillary  vein,  artery,  and  brachial  plexus  of  nerves. 

d.  A  short  arterial  trunk,  the  thoracic  axis,  which  divides  into 
several  radiating  branches. 

e.  The  termination  of  the  cephalic  vein  in  the  axillary. 

/.  Two  nerves,  the  anterior  thoracic,  which  descend  from  the 
brachial  plexus  below  the  clavicle,  and  cross  in  front  of  the  axillary 
vessels  to  supply  the  pectoral  muscles. 

This  muscle  lies  between  the  clavicle  and  the 

first  rib.     It  arises  from  the  first  rib  by  a  short 

round  tendon  at  the  junction  of  the  bone  and  cartilage,  and  is 


INFRA-CLAVICULAR    REGION.  259 

inserted  into  a  groove  on  the  under  surface  of  the  clavicle.  Its 
nerve  comes  from  the  fifth  and  sixth  cervical  nerves.  Its 
action  is  to  depress  the  clavicle,  and  prevent  its  too  great 
elevation. 

KELATIVE  rosi-  In  the  infra-clavicular  space  before  us  are  the 
TION  OF  THE  AXIL-  great  vessels  and  nerves  of  the  axilla  in  the  first 
LAET  VESSELS  AND  par^  of  their  course.  They  lie  at  a  great  depth 
from  the  surface.  They  are  surrounded  by  a 
sheath  of  fascia,  which  descends  with  them  beneath  the  clavicle. 
Their  relations  with  regard  to  each  other  are  as  follows  :  The 
axillary  vein  lies  in  front  of  the  artery,  and  rather  to  its  thoracic 
side.  The  brachial  plexus  of  nerves  is  situated  above  the  artery, 
and  on  a  posterior  plane.  The  plexus  consists  of  two,  or  sometimes 
three,  large  cords,  which  result  from  the  union  of  the  anterior 
branches  of  the  four  lower  cervical,  and  the  first  dorsal,  nerves. 
The  course  and  relations  of  the  axillary  artery  will  be  examined 
subsequently. 

THORACIC  Axis  This  is  the  first  branch  of  the  axillary  artery. 
AND  BEANCHES.  It  comes  off  above  the  pectoralis  minor,  and  soon 
divides  into  three  branches — the  superior  or  short  thoracic,  the 
thoracica  humeraria.  and  the  thoracica  acromialis.  The  superior 
or  short  thoracic  runs  between  the  pectoralis  major  and  minor, 
supplying  both,  and  anastomosing  with  the  intercostal  and  internal 
mammary  arteries.  The  thoracica  humeraria  descends  with  the 
cephalic  vein,  in  the  interval  between  the  pectoralis  major  and 
deltoid,  and  ramifies  in  both.  The  thoracica  acromialis  passes 
over  the  coracoid  process  to  the  under  surface  of  the  deltoid, 
which  it  supplies,  and  communicates  with  the  posterior  circum- 
flex, a  branch  of  the  axillary,  and  the  supra-scapular,  a  branch  of 
the  subclavian.  A  constant  though  small  branch,  the  clavicular, 
given  off  from  this  axis,  runs  along  the  anterior  aspect  of  the  sub- 
clavius.  All  these  arteries  are  accompanied  by  veins,  which  most 
frequently  empty  themselves  into  the  cephalic,  but  occasionally 
into  the  axillary  vein. 

The  cephalic  vein  is  one  of  the  principal  cuta- 
CEPHALIC  VEIN.  . .  ~    ,,  ~  . 

neous  veins  of  the  arm.      Commencing  OD   the 

s  2 


260  INFRA- CLAVICULAR  REGION. 

back  of  the  thumb  and  forefinger,  it  runs  up  the  radial  side  6f  the 
forearm,  in  front  of  the  elbow-joint ;  thence  ascending  along  the 
outer  edge  of  the  biceps,  it  runs  up  the  interval  between  the  pec- 
toralis  major  and  deltoid,  pierces  the  costo-coracoid  membrane, 
and  finally  empties  itself  into  the  axillary  vein.* 

ANTEEIOR  THO-  These  nerves  come  from  the  brachial  plexus  be- 
RACIC  NERVES.  low  the  clavicle  to  supply  the  pectoral  muscles. 
There  are  generally  two — an  external  and  an  internal — one  for  each 
pectoral  muscle.  The  external,  the  more  superficial,  arises  from 
the  outer  cord  of  the  brachial  plexus,  passes  over  the  axillary  artery, 
and  supplies  the  pectoralis  major ;  the  internal  comes  from  the 
internal  cord,  and  runs  between  the  axillary  artery  and  vein,  to  the 
under  surface  of  the  pectoralis  minor. 

^  From  this  view  of  the  relations  of  the  axillary 

DIFFICULTY  OF  _  J 

TYING  THE  FIBS!  artery  in  the  first  part  of  its  course,  some  idea 
PABT  OF  THE  AXIL-  may  be  formed  of  the  difficulty  of  passing  a  ligature 
LAEY  ABTEBY.  round  it  in  this  situation.  In  addition  to  its  great 
depth  from  the  surface,  varieties  sometimes  occur  in  the  position 
of  the  nerves  and  veins,  which  renders  the  operation  still  more 
embarrassing.  For  instance,  the  anterior  thoracic  nerves  may  be 
more  numerous  than  usual,  and  form  by  their  mutual  communi- 
cation a  plexus  around  the  artery.  A  large  nerve  is  often  seen 
crossing  obliquely  over  the  artery,  immediately  below  the  clavicle, 
to  form  one  of  the  roots  of  the  median  nerve.  The  cephalic  vein 
may  ascend  higher  than  usual,  and  open  into  the  subclavian  ;  and 
as  it  receives  large  veins  corresponding  to  the  thoracic  axis,  a  con- 
course of  veins  would  be  met  with  in  front  of  the  artery.  Again, 
it  is  by  no  means  uncommon  to  find  a  deep-seated  vein,  the  supra- 
scapular,  crossing  over  the  artery  to  join  the  axillary  vein. 

*  The  cephalic  vein,  in  some  cases,  runs  over  the  clavicle  to  join  the  external 
jugular;  or  there  maybe  a  communication  (termed  jugulo-cephalic)  between  these 
veins. 


AXILLAET    FASCIA.  261 

DISSECTION   OF   THE  AXILLA. 

SEBACEOUS  On  the  under  surface  of  the  skin  of  the  axilla, 

GLANDS.  near  the  roots  of  the  hairs,  are  numerous  sebaceous 

glands.  They  are  of  a  reddish-brown  colour,  and  rather  larger 
than  a  pin's  head. 

AXILLARY  FAS-  This  dense  fascia,  which  lies  immediately  be- 
CIA-  neath  the  skin  of  the  axilla,  is  a  continuation  of 

the  general  investment  of  the  muscles.  It  closes  in  and  forms  the 
floor  of  the  cavity  of  the  axilla.  Externalty,  it  is  strengthened  by 
fibres  from  the  tendons  of  the  pectoralis  major  and  latissimus 
dorsi,  and  is  continuous  with  the  fascia  of  the  arm ;  internally,  it 
is  prolonged  on  the  side  of  the  chest,  over  the  serratus  magnus 
muscle ;  in  front  and  behind  it  divides,  so  as  to  inclose  between 
its  layers  the  muscles  which  form  the  boundaries  of  the  axilla. 
Thus  the  anterior  layer  incloses  the  two  pectoral  muscles,  and  is 
connected  with  the  coracoid  process,  the  costo-coracoid  ligament, 
and  the  clavicle ;  the  posterior  layer  incloses  the  latissimus  dorsi, 
and  passes  backwards  to  the  spine. 

A  subcutaneous  artery,  sometimes  of  considerable  size,  is  often 
found  in  the  substance  of  the  axillary  fascia.  It  generally  arises 
from  the  brachial,  or  from  the  lower  part  of  the  axillary,  and  runs 
across  the  floor  of  the  axilla  towards  the  lower  edge  of  the  pecto- 
ralis major.  It  is  not  a  named  branch,  but  should  be  remembered, 
as  it  would  occasion  much  haemorrhage  if  wounded  in  opening  an 
abscess. 

DISSECTION  AND  Reflect  the  axillary  fascia,  to  display  the 
CONTENTS  OF  THE  boundaries  and  the  contents  of  the  axilla.  The 
AXILLA.  dissection  of  this  space  is  difficult,  and  must  be 

done  cautiously.  Bear  in  mind  that  the  trunk  blood-vessels  and 
nerves  run  through  the  upper  and  outer  part  of  the  axilla ;  that 
the  long  thoracic  artery  runs  along  the  anterior  border,  and  the 
subscapular  artery  along  the  posterior.  Commence  dissecting, 
therefore,  in  the  middle ;  break  down  with  the  handle  of  the 
scalpel  the  loose  connective  tissue,  fat,  and  lymphatic  glands,  which 
occupy  the  cavity.  You  will  soon  discover  some  cutaneous  nerves 


262  BOUNDARIES    OF    AXILLA. 

coming  out  between  the  ribs,  and  then  crossing  the  axillary  space. 
These  nerves  are  the  lateral  cutaneous  branches  of  the  intercostal 
nerves ;  they  perforate  the  intercostal  spaces  between  the  digita- 
tions  of  the  serratus  magnus,  midway  between  the  sternum  and 
the  spine,  and  divide  into  anterior  and  posterior  branches.  The 
anterior  turn  over  the  pectoralis  major,  to  supply  the  skin  on  the 
front  of  the  chest  and  the  mammary  gland.  The  -posterior  pass 
backwards  over  the  latissimus  dorsi,  and  are  distributed  to  the  skin 
covering  this  muscle  and  the  scapula. 

INTERCOSTO-HU-  The  posterior  lateral  branch  of  the  second  inter- 
MEEAL  NERVES.  costal  nerve  requires  a  special  description ;  it  is 
larger  than  the  others,  and  is  called  the  intercosto-humeral  be- 
cause it  supplies  the  integuments  of  the  arm.  It  comes  through 
the  second  intercostal  space,  traverses  the  upper  part  of  the  axilla, 
where  it  receives  a  branch  of  the  lesser  internal  cutaneous  nerve 
(nerve  of  Wrisberg),  and  terminates  in  filaments,  which  are  dis- 
tributed to  the  skin  on  the  inner  side  of  the  arm,  as  low  as  the 
internal  condyle.  The  corresponding  branch  of  the  third  inter- 
costal is  also  an  intercosto-humeral  nerve.  It  receives  a  branch 
from  the  second,  and  runs  a  similar  course.  The  distribution  of 
these  nerves  accounts  for  the  pain  down  the  arm  which  is  sometimes 
experienced  in  pleurisy. 

BOUNDARIES  OF  The  axilla  is  a  conical  space,  of  which  the 
THE  AXILLA.  summit  is  beneath  the  clavicle,  and  the  base  be- 

tween the  pectoralis  major  and  the  latissimus  dorsi.  Obviously  it 
varies  in  capacity  according  to  the  position  of  the  arm.  On  the 
inner  side,  it  is  bounded  by  the  four  upper  ribs,  covered  by  the 
serratus  magnus ;  on  the  outer,  by  the  humerus,  covered  by  the 
coraco-brachialis  and  biceps;  in  front,  by  the  pectoralis  major  and 
minor ;  behind,  by  the  latissimus  dorsi,  teres  major,  and  subscapu- 
laris.  Its  anterior  and  posterior  boundaries  converge  from  the 
chest,  so  that  the  axilla  becomes  narrower  towards  the  arm.  With 
a  full  view  of  the  axilla  before  you,  bear  in  mind  that  pus  may 
burrow  under  the  pectoral  muscles,  or  under  the  scapula,  or  that  it 
may  run  up  beneath  the  clavicle  and  point  in  the  neck,  if  the 
abscess  be  allowed  to  remain  unopened. 


AXILLARY    ARTERY.  263 

AXILLARY  LTM-  The  axillary  glands  form  a  continuous  chain, 
PHATIO  GLANDS.  beneath  the  clavicle,,  with  the  cervical  glands. 
They  are  from  ten- to  twelve  in  number,  of  a  reddish-brown  colour, 
and  variable  size.  Most  of  them  lie  near  some  large  blood-vessel ; 
others  are  embedded  in  the  loose  tissue  of  the  axilla ;  sometimes 
one  or  two  small  ones  are  observed  along  the  lower  border  of  the 
pectoralis  major.  They  are  supplied  with  blood  by  a  branch — 
thoradca  alaris — of  the  axillary  artery,,  and/ by  branches  -from  the 
thoracic  and  subscapular  arteries. 

These  glands  receive  the  lymphatics  from  the  arm,  from  the 
front  and  side  of  the  chest,  and  from  the  outer  half  of  the  mam- 
mary gland.  From  these  glands  the  efferent  lymphatics  pass  along 
with  the  subclavian  artery  and  terminate,  on  the.  right  side,  in  the 
right  lymphatic  duct,  and  on  the  left  side$  in  the  thoracic  duct. 

DISSECTION.  Now  reflect  the  pectoralis  major  from-,  its  torigin, 

to  expose  the  pectoralis  minor,  and  the  ramifications  of  the  short 
and  long  thoracic  arteries.  Preserve  the  arteries,  as  far  as  possible, 
in  connection  with  the  main  trunks. 

PECTORALIS  This  muscle  arises  from  the  third,  fourth,  and 

MINOR.  fifth  ribs,  near  the  costal  cartilages,  and  from  the 

thick  fascia  over  the  intercostal  spaces.  The  fibres  run  obliquely 
upwards  and  outwards,  and  converge  to  a  strong  tendon,  which 
is  inserted  into  the  anterior  surface  of  the  coracoid  process.  The 
tendon  is  connected  to  that  of  the  coraco-brachialis  and  biceps 
by  a  strong  fascia,  which  forms  a  protection  for^  the  subjacent 
axillary  vessels  and  nerves. .  The  action-  of  this  muscle  is  to  draw 
the  scapula  downwards  and  .for-wards.  Its  nerve  is  derived  from 
the  internal  anterior  thoracic; 

DISSECTION.  Having  examined  the  muscles  which  form  the 
anterior  boundary  of  the  axilla,  we  pass  now  to  the  course  and 
relations  of  the  axillary  artery  and  its  branches.  To  have  a  clear 
view,  reflect  the  subclavius  from  its  insertion,  and  the  pectoralis 
minor  from  its  origin. 

AXILLARY  AR-  This  artery,  the  continuation  of  the  subclavian, 
TERY,  ITS  COURSE  takes  the  name  of  axillary  at  the  outer  border  of 
AND  RELATIONS.  the  fjrsfc  j-fa  jt  then  passes  downwards  and  out- 


264  BRANCHES    OF    AXILLAET    ARTFRY. 

wards,  through  the  upper  part  of  the  axilla,  beneath  the  two  pec- 
toral muscles,  and  along  the  inner  border  of  the  coraco-brachialis, 
as  far  as  the  lower  border  of  the  tendon  of  the  teres  major,  beyond 
which  it  is  continued  under  the  name  of  the  brachial.  Its  course 
is  divided  for  convenience  of  description  into  three  parts  :  the  first 
lies  above  the  pectoralis  minor  ;  the  second  behind  that  muscle ; 
and  the  third  below  it. 

In  the  first  part  of  its  course,  the  artery  is  covered  by  the 
pectoralis  major  and  the  costo-coracoid  membrane,  and  is  crossed 
by  the  cephalic  and  acromio-thoracic  veins.  On  its  inner  side, 
and  slightly  in  front,  is  the  axillary  vein  ;  on  its  outer  side  is  the 
brachial  plexus  of  nerves ;  behind  it  are  the  first  intercostal  space, 
the  second  digitation  of  the  serratus  magnus,  and  the  posterior 
thoracic  nerve  (external  respiratory  of  Bell). 

In  the  second  part  of  its  course,  it  lies  behind  the  pectoralis 
major  and  minor ;  on  its  inner  side  is  the  axillary  vein,  still 
slightly  anterior,  but  separated  from  the  artery  by  the  inner  cord 
of  the  brachial  plexus ;  on  its  outer  side  is  the  outer  cord  of  the 
brachial  plexus ;  and  behind  it  is  a  quantity  of  loose  connective 
tissue  which  separates  it  from  the  subscapularis  muscle.  The 
inner  head  of  the  median  nerve  is  often  in  front  of  the  artery  in 
this  part  of  its  course. 

In  the  third  part,  in  front  of  the  artery,  are  the  pectoralis 
major,  the  two  roots  of  the  median  nerve,  converging  like  the 
letter  V,  and  lower  down  is  the  fascia  of  the  arm ;  on  the  outer 
side  are  the  coraco-brachialis,  the  musculo-cutaneous  and  median 
nerves ;  on  the  inner  side  are  the  axillary  vein,  the  ulnar,  and 
the  two  internal  cutaneous  nerves ;  behind  it  are  in  succession  the 
subscapularis,  the  latissimus  dorsi,  the  teres  major,  and  the  mus- 
culo-spiral  and  circumflex  nerves. 

BRANCHES  OF  The  number  and  origin  of  these  branches  often 

THK    AXILLABY        vary,  but  their  general  course  is  in  most  cases 
ARTERY.  similar,  and  they  usually  arise  in  the  following 

order : — 

a.  The  thoracic  axis  arises  above  the  pectoralis  minor,  and  divides 
into  branches,  which  have  been  already  described  (p.  259) 


BRANCHES    OF    AXILLARY    ARTERY.  265 

b.  The  alar  thoracic,  variable  in  its  origin,  supplies  the  lymphatic 
glands  and  the  connective  tissue  of  the  axilla. 

c.  The  inferior  or  long  thoracic  artery  (external  mammary)  runs 
along  the  lower  border  of  the  pectoralis  minor.  It  supplies  the  mammary 
gland,  the  serratus  magnus  and  pectoral  muscles,  and  maintains  a  free 
anastomosis  with  the  short  thoracic,  internal  mammary,  and  intercostal 
arteries. 

d .  The  subscapular  is  the  largest  branch  of  the  axillary ;  it  arises 
opposite  the  lower  border  of  the  subscapularis,  and  soon  divides  into  an 
anterior  and  posterior  branch. 

The  anterior  branch  runs  along  the  anterior  edge  of  the  subscapu- 
laris towards  the  lower  angle  of  the  scapula.     Its  numerous  branches 


PLAN   OF   THE    BRANCHES    OF   THE    AXILLARY    ARTERY. 

1 .  Thoracic  axis,  giving  off  6.  Subscapular. 

2.  Short  thoracic.  7.  Dorsalis  scapulae. 

3.  Thoracica  acromialis.  8.  Anterior  circumflex. 

4.  Thoracica  humeraria.  •$.  Posterior  circumflex. 
5.  Long  thoracic. 

supply  the  subscapularis,  latissimus  dorsi,  serratus  magnus,  and  teres 
major,  and  anastomose  with  the  intercostal  and  thoracic  arteries,  and  the 
posterior  scapular  (a  branch  of  the  siibclavian). 

The  posterior  branch  (dorsalis  scapulae)  runs  to  the  back  of  the 
scapula,  through  a  triangular  space,  bounded  in  front  by  the  long  ^head 
of  the  triceps  ;  below,  by  the  teres  major  ;  and  above,  by  the  subscapu- 
lar and  teres  miner  (diagram,  p.  266).  On  the  back  of  the  scapula,  it 
divides  into '^branches,  which  ramify  close  to  the  bone,  supplying  the  infra- 
spinatus  and  teres  minor,  and  anastomose  with  the  supra-scapular  and 
posterior  scapular  arteries  (diagram,  p.  69).  The  subscapular  vein  empties 
itself  into -the  axillary  vein. 


266 


BRANCHES    OF    AXILLARY    ARTERY. 


CIRCUMFLEX 
ARTERIES,  ANTE- 
RIOR   AND   POS- 
TERIOR. 


There  are  two  circumflex  arteries  — an  anterior 
and  a  posterior,  so  called  from  the  manner  in 
which  they  encircle  the  neck  of  the  humerus. 
The  posterior  circumflex  artery  is  as  large  as  the 
subscapular,  close  to  which  it  is  given  off ;  or  both  may  arise  from 
a  common  trunk'  from  the  axillary.  It  passes  backwards  through 
a  quadrilateral  space,.*  bounded  above  by  the  subscapularis  and 
teres  minor,  below  by  the  teres  major,  externally  by  the  neck  of 
the  humerus,  and  internally  by  the  long,  head  of  the  triceps 
53).  It  then  winds  round  the  back  of  the  neck  of  the 

FIG.  -53. 


1.  Subscapularis.  . 

2.  Teres  major. 

3.  Long  head  of  triceps. 

4.  Square  space  for  cir- 

cumflex a.  and  n. 


5.  Triangular  space  for  dor- 

salis  scapulae  a. 

6.  Space  for  musculo-spiral 

n.,  and   superior  pro- 
funda  a. 


DIAGRAM    OF    THE    ORIGINS    OF    THE   TRICEPS. 

humerus,  and  is  chiefly  distributed  to  the  under  surface  of  the 
deltoid. 

Besides  the  deltoid,  the  posterior  circumflex  artery  supplies  the 
long  head  of  the  triceps,  the  head  of  the  humerus,  and  the  shoulder- 
joint.  It  inosculates  above  with  the  acromio-thoracic  and  supra- 
scapular  arteries,  below  with  the  ascending  branch  of  the  superior 
profunda  (a  branch  of  the  brachial),  and  in  front  with  the  anterior 
circumflex  artery.  Should  you  not  find  the  posterior  circumflex 
artery  in  its  normal  position,  look  for  it  (as  a  branch  of  the 
brachial)  below  the  tendon  of  the  teres  major. 


AXILLAET    PLEXUS    OF    NERVES.  267 

The  anterior  circumflex  artery,  much  smaller  than  the  pos- 
terior, runs  in  front  of  the  neck  of  the  humerus,  above  the  tendon 
of  the  latissimus  dorsi.  It  passes  directly  outwards  beneath  the 
coraco-brachialis  and  short  head  of  the  biceps,  close  to  the  bone, 
and  terminates  in  the  under  surface  of  the  deltoid,  where  it  inoscu- 
lates with  the  posterior  circumflex. 

The  anterior  circumflex  artery  sends  a  small  branch  which  runs 
with  the  long  tendon  of  the  biceps  up  the  groove  of  the  humerus, 
and  is  called,  on  that  account,  the  bicipital  artery.  It  supplies  the 
shoulder-joint  and  the  neck  of  the  humerus.* 

AXILLARY  VEIN.  The  axillary  vein-  is  formed  by  the  junction  of 
the  vena3  comites  of  the  brachial  artery,  near,  the  lower  border  of 
the  subscapularis.  It  receives  the  subscapular  and  the  other  veins 
corresponding  to  the  branches  of  the  axillary  artery,  with  the 
exception  of  the  circumflex,  which  usually  join  either  the  subscapular 
or  one  of  the  venre  comites.  The  axillary  also  receives  the  cephalic, 
and  sometimes  the  basilic  vein. 

The  axillary  vein  in  the  first  part  of  its  course  lies  in  front  of 
the  artery,  and  close  to  its  sternal  side ;  in  the  lower  two- thirds  of 
its  course  the  vein  lies  still  to  the  sternal  side  of  the  artery,  but  is 
separated  from  it  by  some  of  the  nerves  of  the  brachial  plexus. 

AXILLARY  OB  This  plexus  is  formed  by  the  anterior  trunks  of 

BRACHIAL  PLEXUS  the  four  lower  cervical  and  first  dorsal  nerves,  and 
OF  NEBVES.  receives  also  a  small  communicating  branch  from 

the  fourth  cervical  nerve.  The  plexus  is  broad  at  the  lower  part  of 
the  neck,  where  it  emerges  between  the  anterior  and  middle  scalene 
muscles ;  but  it  gradually  contracts  as  it  descends  beneath  the 
clavicle  into  the  axilla. 

The  arrangement  of  the  cervical  nerves  in  the  formation  of  the 
plexus  is  variable,  often  not  alike  on  both  sides.  The  most  fre- 
quent disposition  is  this — the  fifth  and  sixth  cervical  unite  to  form 
a  single  cord ;  the  eighth  and  the  first  dorsal  form  another  cord ; 

*  If  the  axillary  were  tied  below  the  pectoralis  minor,  the  collateral  circulation 
•would  be  established  by  the  supra-scapular  and  its  branches  anastomosing  with  the 
subscapular,  the  dorsalis  scapulae,  and  the  posterior  circumflex :  the  posterior  scapular 
with  the  dorsalis  scapulas  and  subscapular. 


268 


AXILLARY   PLEXUS    OF    NERVES. 


the  seventh  cervical  runs  alone  for  a  short  distance.  Each  of  these 
nerves  divides  into  an  anterior  and  a  posterior  branch  ;  the  anterior 
branches  given  off  from  the  fifth,  sixth,  and  seventh  cervical  form 
the  outer  cord  of  the  plexus ;  the  anterior  branches  given  off  from 
the  eighth  cervical  and  the  first  dorsal  form  the  inner  cord;  while 

Fio.  54. 


THE    BRACHIAL    PLEXUS    OF    NEEVES. 


c  4-8.  The  five  lower  cervical  nerves. 
D  1.  The  first  dorsal  nerve. 
9.  The  rhomboid  nerve — to  rhomboidei 
major  and  minor. 

10.  The  supra-scapular  nerve— to  supra 

and  infra  spinati. 

11.  The  nerve  to  the  subclavius. 

12.  Outer  anterior   thoracic  nerve — to 

pectoralis  major 

13.  Inner    anterior   thoracic  nerve — to 

pectoralis  minor. 


14, 15, 16.  The  gubscapular  nerves— to  subscapu- 
laris,  latissimus  dorsi,and  teres  major. 

17.  Lesser  internal  cutaneous  nerve. 

18.  Musculo-cutaneous  nerve . 

19.  Musculo-spiral  nerve  or  radial. 

20.  Median  nerve. 

21.  Circumflex  nerve — to  deltoid  and  teres 

minor. 

22.  Ulnar  nerve. 

23.  Internal  cutaneous  nerve. 

24.  External  respiratory  nerve  of  Bell,  or 

posterior  thoracic. 


the  posterior  branches  of  all  the  nerves — viz.,  the  fifth,  sixth, 
seventh,  eighth  cervical  and  the  first  dorsal — unite  to  form  the 
posterior  cord. 


BBANCHES    OP    AXILLAET    PLEXUS.  269 

The  axillary  plexus  gives  off  some  branches  above  the  clavicle, 
which  were  dissected  with  the  neck  (p.  72).  Below  the  clavicle, 
it  gives  off  the  following  : — 

From  the  outer  cord  proceed  an  anterior  thoracic  branch,  the 
musculo-cutaneous,  and  the  outer  head  of  the  median ;  from  the 
inner  cord  proceed  the  inner  anterior  thoracic  nerve,  the  inner 
head  of  the  median,  the  ulnar,  the  internal  cutaneous,  and  the  lesser 
internal  cutaneous  ;  from  the  posterior  cord  proceed  the  three  sub- 
scapular  nerves,  the  circumflex  and  the  musculo-spiral. 

The  anterior  thoracic  nerves  have  been  described  (p.  260). 
SUBSCAPULAR  The  three  subscapular  nerves  are  found  on  the 

NERVES.  surface  of  the  subscapular  is.    They  come  from  the 

posterior  cord  of  the  brachial  plexus,  and  supply,  respectively,  the 
latissimus  dorsi,  teres  major,  and  subscapularis.  The  nerve  for 
the  latissimus  dorsi  (long  subscapular  nerve)  runs  with  the  an- 
terior branch  of  the  subscapular  artery  to  the  lower  border  of  the 
muscle. 

The  nerve  for  the  teres  major  is  either  a  branch  of  the  pre- 
ceding, or  comes  separately  from  the  posterior  cord.  It  lies  nearer 
to  the  humerus  than  the  long  subscapular. 

The  nerve  of  the  subscapularis  arises  from  the  posterior  cord 
higher  than  the  others,  and  enters  the  muscle  not  far  from  its 
upper  border  in  company  with  a  small  artery. 

CIRCUMFLEX  The  circumflex  nerve  accompanies  the  posterior 

NERVE.  circumflex  artery.     This  large  nerve  comes  from 

the  posterior  cord,  and,  after  giving  a  small  filament  to  the  shoulder- 
joint,  passes,  with  its  companion  artery,  through  the  quadrilateral 
space  (p.  266)  to  the  under  surface  of  the  deltoid.  Here  the  nerve 
divides  into  an  upper  and  a  lower  branch.  The  upper  supplies 
the  anterior  part  of  the  deltoid  and  the  skin  over  it ;  the  lower 
supplies  the  back  part  of  the  deltoid,  and  gives  the  nerve  to  the 
teres  minor,*  upon  which  nerve  sometimes  a  little  gangliform  swell- 
ing can  be  seen.  After  furnishing  these  muscular  branches,  the 
nerve  turns  round  the  posterior  border  of  the  deltoid,  and  diverges 

*  This  branch  to  the  teres  minor  is  said  to  be  constant  in  all  mammalia  that  have 
been  examined  in  reference  to  this  point. 


270  POSTERIOR   BOUNDARIES    OF    AXILLA. 

in  filaments  which  supply  the  skin  over  the  back  of  this  muscle 
and  over  the  long  head  of  the  triceps. 

LATISSIMUS  This  muscle  forms  the  posterior  margin  of  the 

DORSI.  axilla.    It  arises  from  the  crest  of  the  ilium,  from 

the  spines  of  the  two  or  three  upper  sacral,  all  the  lumbar,  and  six 
lower  dorsal  vertebrae,  and  by  digitations  from  the  three  lower  ribs, 
corresponding  with  those  of  the  external  oblique ;  in  some  cases, 
as  it  passes  over  the  inferior  angle  of  the  scapula,  it  has  an  addi- 
tional origin  from  the  angle.  It  is  inserted  by  a  broad  flat  tendon, 
which  runs  behind  the  axillary  vessels  and  nerves,  into  the  bottom 
of  the  bicipital  groove  of  the  humerus.  Its  nerve  is  the  long  sub- 
scapular  branch  of  the  brachial  plexus. 

This  muscle  lies  behind  the  latissimus  dorsi,  is 
TERES  MAJOB.  ,        ,  .     ,       .. ,      . .  ,          .  ,      .       f 

closely  connected  with  it,  and  assists  in  torming 
the  posterior  boundary  of  the  axilla.  It  arises  from  the  lower 
angle  of  the  back  of  the  scapula,  and  is  inserted  by  a  broad  flat 
tendon  into  the  posterior  margin  of  the  bicipital  groove  of  the 
humerus.  A  bursa  or  sac,  containing  serum,  to  diminish  friction, 
intervenes  between  this  tendon  and  that  of  the  latissimus  dorsi. 
The  action  of  this  and  the  preceding  muscle  is  to  draw  the 
humerus  inwards  and  backwards.  Its  nerve  is  the  middle  sub- 
scapular. 

This  muscle  arises  from  the  internal  surface  of 
the  scapula,  with  the  exception  of  the  angles  and 
neck,  and  from  intermuscular  septa  attached  to  the  bony  ridges. 
Its  fibres  terminate  on  a  strong  tendon,  which  passes  under  the 
axillary  vessels  and  nerves,  over  the  inner  side  of  the  shoulder- 
joint,  and  is  inserted  into  the  lesser  tuberosity  of  the  humerus. 
The  tendon  of  the  muscle  is  intimately  connected  with  the  cap- 
sular  ligament  of  the  shoulder-joint,  and  between  the  coracoid 
process  and  the  tendon  is  a  bursa,  which  frequently  communicates 
with  the  joint.  Its  action  is  to  rotate  the  humerus  inwards.  Its 
nerve  comes  from  the  posterior  cord  of  the  brachial  plexus. 

SERBATUS  This  muscle  covers  the  side  of  the  chest  like  a 

MAGNUS.  girth.     It  arises  from  the  eight  upper  ribs  by 

nine  slips  or  digitations,  the  second  rib  having  two.     Its  fibres 


DISSECTION    OF    THE    UPPER    ARM.  271 

converge  and  are  inserted  into  the  posterior  border  of  the  scapula 
in  the  following  manner :  the  first  two  digitations  are  attached 
into  the  upper  angle  of  the  scapular ;  the  third  and  fourth  digita- 
tions along  nearly  the  whole  length  of  the  posterior  border ;  the 
remainder  are  inserted  into  the  inferior  angle.  Its  action  is  to 
draw  the  scapula  forwards  ;  but  of  this  more  hereafter.  It  is  sup  • 
plied  by  the  following  nerve,  which  is  seen  on  its  outer  surface. 

This  nerve  supplies  the  serratus  magnus  only. 
POSTERIOR  THO-  J 

KACIC  OK  EXTER-  It  comes  from  the  fifth  and  sixth  cervical  nerves ; 
NAL  RESPIRATORY  and,  after  passing  through  the  scalenus  medius, 
NERVE  OF  BELL.  mng  behm(}  the  axillary  vessels,  along  the  outer 
surface  of  the  serratus  magnus,  each  digitation  receiving  a  sepa- 
rate filament.* 


DISSECTION   OF   THE   UPPER  ARM. 

Continue  the  incision  down  the  inner  side  of 
the  arm  as  far   as  two  inches  below  the  elbow. 
Keflect  the  skin,  and  trace  out  the  cutaneous  nerves,  and  the 
numerous  veins  in  front  of  the  elbow. 

CUTANEOUS  On  the  inner  side  of  the  arm  are  the  intercosto- 

NERVES.  humeral,  the   internal  cutaneous  branch  of  the 

musculo-spiral,  the  internal  cutaneous  and  the  lesser  internal 
cutaneous  (nerve  of  Wrisberg)  nerves ;  on  the  outer  side  are  the 
cutaneous  branches  of  the  circumflex,  the  external  cutaneous 
branches  of  the  musculo-spiral,  and  lower  down  is  the  musculo- 
cutaneous  nerve. 

The  filaments  of  the  intercosto-humeral  nerves  (p.  262)  descend  along 
the  inner  and  posterior  part  of  the  arm  as  far  as  the  olecranon. 

The  branches  of  the  internal  cutaneous  nerve  perforate  the  fascia 
about  the  middle  of  the  arm,  and  divide  into  an  anterior  and  a  posterior 
branch ;  the  anterior  passes  down  in  front  of  the  arm  (as  a  rule  beneath 
the  median  basilic  vein),  and  supplies  the  skin  as  far  as  the  wrist ;  the 

*  It  may  be  asked  why  this  nerve  is  called  the  external  respiratory.  It  was  so 
named  by  Sir  0.  Bell,  who  considered  the  serratus  magnus  as  the  external  respiratory 
muscle,  co-operating  with  the  diaphragm  or  internal  respiratory  muscle. 


272 


CUTANEOUS    NERVES    OF    THE    ARM. 


posterior  winds  round  to  the  back  of  the  forearm  behind  the  internal 
condyle,  and  communicates  with  the  nerve  of  Wrisberg  and  the  ulnar 
nerve. 

The  lesser  internal  cutaneous  (nerve  of  Wrisberg")  perforates  the 
fascia  about  the  lower  third  of  the  arm,  and  supplies  the  skin  over  the 
internal  condyle  and  the  olecranon.  This  nerve,  as  it  lies  close  to  the 

FIG.  55. 


1.  Acromial   \  of    the   su- 

branches  [  perflcialcer- 

2.  Clavicular  N^P^us. 

branches  / 

3.  Cutaneous  branches   of 

the  circumflex  nerve. 

4.  Branches  of  the  internal 
cutaneous  nerve. 


5.  External          cutaneous 

branch    of   the    mus- 
culo-spiral  nerve. 

6.  Internalcutaneousnerve. 

7.  Its  posterior   cutaneous 

branch. 

8.  The  cutaneous  branch  of 

the  musculo-cutaneous 
nerve. 


DISTRIBUTION  OF  CUTANEOUS  NERVES  TO  THE  FEONT  OF  THE  SHOULDER 
AND  ARM. 

axillary  vein,  communicates  with  the  first  or  second  intercosto- humeral 
nerve. 

The  internal  cutaneous  branch  of  the  musculo-spiral  nerve  pierces  the 
fascia,  and  supplies  the  skin  of  the  inner  side  of  the  middle  of  the  arm. 

The  cutaneous  branches  of  the  circumflex  nerve  pierce  the  fascia  over 
the  insertion  of  the  deltoid,  and  supply  the  skin  of  the  upper  half  of  the 
arm  on  its  outer  side. 


VEINS    AT    THE    ELBOW. 


273 


The  external  cutaneous  branches  of  the  musculo-spiral  nervs  are  two 
in  number  :  the  upper  and  smaller  accompanies  the  cephalic  vein  in  the 
lower  half  of  the  arm ;  the  lower  may  be  traced  down  the  outer  and 
back  part  of  the  forearm  nearly  as  far  as  the  wrist,  where  it  joins  the 
musculo-cutaneous  nerve. 

On  the  outer  side  of  the  tendon  of  the  biceps,  the  cutaneous  branch 
of  the  musculo-cutaneous  nerve  perforates  the  fascia,  and  divides  into 
many  filaments,  which  supply  the  skin  of  the  outer  part  of  the  fore- 
arm. 

FIG.  56. 


Basilic  vein     ...    — 


Median  basilic  vein  .    . 


Deep  median  vein    .    . 


Cephalic  vein. 


Median  cephalic  vein. 


Median  vein. 


SUPERFICIAL  VEINS  AND  NERVES  AT  THE  BEND  OF  THE  LEFT  ELBOW. 


DISPOSITION  OF 
VEINS  IN  FRONT  OF 
THE  ELBOW. 


Attention  should  now  be  directed  to  the  dis- 
position of  the  veins  in  front  of  the  elbow.  In 
cleaning  these  veins,  take  care  not  to  divide  the 
branches  of  the  internal  and  external  cutaneous  nerves  which  pass 
over  and  under  them. 

The  following  is  the  ordinary  arrangement  of  the  superficial 

T 


274  VEINS   AT   THE    ELBOW. 

veins  at  the  bend  of  the  elbow  (fig.  56).  On  the  outer  side  is  the 
radial ;  on  the  inner  side  is  the  ulnar  vein,  formed  by  the  junction 
of  the  anterior  and  posterior  ulnar  cutaneous  veins  ;  in  the  centre 
is  the  median,  which  divides  into  two  branches,  the  external  of 
which,  uniting  with  the  radial  to  form  the  cephalic  vein,  is  called 
the  median  cephalic-,  the  internal,  uniting  with  the  ulnar  to 
form  the  basilic,  is  named  the  median  basilic.  Near  its  bifur- 
cation, the  median  vein  communicates  by  a  branch  (mediana 
profunda)  with  the  deep  veins  which  accompany  the  arteries  of  the 
forearm. 

Trace  the  cephalic  vein  up  the  arm.  It  runs  along  the  outer 
border  of  the  biceps  to  the  groove  between  the  pectoralis  major  and 
the  deltoid,  where  it  terminates  in  the  axillary  vein. 

The  basilic  vein  ascends  along  the  inner  side  of  the  arm  with 
the  internal  cutaneous  nerve.  Near  the  upper  third  of  the  arm, 
it  perforates  the  fascia,  and  empties  itself  either  into  the  in- 
ternal vena  comes  of  the  brachial  artery  or  into  the  axillary 
vein. 

The  principal  branches  of  the  cutaneous  nerves 
KELATION  OF  r 

THE  CUTANEOUS  Pass  beneath  the  veins :  that  is  to  say,  as  a  rule, 
NERVES  AND  VEINS  the  internal  cutaneous  passes  behind  the  median 
AT  THE  ELBOW.  basilic  vein,  and  the  external  cutaneous  behind 
the  median  cephalic :  but  it  should  be  remembered  that  many 
small  filaments  cross  in  front  which  are  exposed  to  injury  in 
venesection. 

Since  the  median  basilic  vein  is  larger  than  the 
KELATION    OF 

MBDIAN  BASILIC  median  cephalic,  and,  on  account  of  the  strong 
VEIN  TO  BEA-  fascia  beneath,  more  easily  compressible,  it  is 
CHIAL  AKTEEY.  usually  chosen  for  venesection ;  its  position,  there- 
fore, in  reference  to  the  brachial  artery,  becomes  important. 
The  vein  is  only  separated  from  the  artery  by  the  semilunar  fascia, 
derived  from  the  tendon  of  the  biceps.  This  fascia  is  in  some 
subjects  remarkably  thin.  Sometimes  the  artery  lies  above  the 
fascia,  in  contact  with  the  vein.  In  choosing,  therefore,  this 
vein  for  venesection,  there  is  a  risk  of  wounding  the  artery ;  hence 
the  practical  rule,  to  bleed  either  from  the  median  cephalic,  or 


FASCIA   OP   THE    ARM.  275 

from  the  median  basilic  above  the  situation  where  it  crosses  the 
brachial  artery. 

LYMPHATIC  Immediately  above  the  internal  condyle,  in  the 

GLANDS.  neighbourhood  of  the  basilic  vein,  we  find  one  or 

two  small  lymphatic  glands.  Others  may  be  higher  up  along  the 
inner  side  of  the  arm.  A  gland  is  occasionally  met  with  at  the 
bend  of  the  elbow  ;  but  never  below  this  joint.  These  little  glands 
are  the  first  which  are  liable  to  become  tender  and  enlarged  after 
a  poisoned  wound  of  the  hand. 

MUSCULAB  ^ne   fascia  which  invests  the  muscles   of  the 

FASCIA  AND  ITS  upper  arm  is  a  continuation  of  the  fascia  of  the 
CONNECTIONS.  trunk  and  the  axilla.  This  membrane  varies  in 

density ;  thus  it  is  thin  over  the  biceps,  stronger  on  the  inner  -side 
of  the  arm,  to  protect  the  brachial  vessels  and  nerves,  and  strongest 
over  the  triceps.  At  the  upper  part  of  the  arm  it  is  connected 
with  the  coracoid  process  and  the  clavicle ;  it  is  strengthened  at 
the  axilla  by  an  expansion  from  the  tendons  of  the  pectoralis  major 
and  latissimus  dorsi ;  posteriorly,  it  is  attached  to  the  spine  of  the 
scapula.  The  fascia  surrounds  the  brachial  vessels  with  a  sheath, 
and  furnishes  partitions  which  separate  the  muscles  from  each 
other.  Of  these  partitions,  the  most  marked  are  the  external 
and  internal  intermuscular  septa,  which  divide  the  muscles  on 
the  anterior  from  that  on  the  posterior  surface  of  the  upper  arm. 
These  septa  are  attached  to  the  condyloid  ridges  of  the  humerus 
and  to  the  condyles.  The  internal  intermuscular  septum,  the 
stronger  of  the  two,  begins  at  the  insertion  of  the  coraco-brachialis, 
and  separates  the  triceps  extensor  from  the  brachialis  anticus.  The 
external  intermuscular  septum  commences  from  the  insertion  of 
the  deltoid,  and  separates  the  brachialis  anticus,*  the  supinator 
longus,  and  the  extensor  carpi  radialis  longior  in  front,  from  the 
triceps  extensor  behind. 

At  the  lower  part  of  the  upper  arm,  the  fascia  is  remarkably 
strong,  especially  where  it  covers  the  brachialis  anticus,  and  the 
brachial  vessels,  and  is  continued  over  the  muscles  on  the  inner 
side  of  the  forearm.  At  the  back  of  the  elbow,  the  fascia  is 
attached  to  the  tendon  of  the  triceps,  and  the  olecranon. 

T    2 


276  MUSCLES    OF    THE    ARM. 

Now   remove  the   fascia   in   order  to   see   the 

Dl*  SECTION 

muscles  on    the  front  of  the  arm — namely,  the 
biceps,  the  coraco-brachialis,  and  the  brachialis  anticus. 

The  biceps,  as  its  name  implies,  arises  by  two 
BICEPS  ' 

heads — a    long    and   a   short.     The    short    head 

arises  from  the  point  of  the  coracoid  process  of  the  scapula,  by 
a  thick,  flat  tendon  in  common  with  a  slender  muscle  on  its 
inner  side,  called  the  coraco-brachialis.  The  long  head  arises 
from  the  upper  border  of  the  glenoid  fossa  of  the  scapula  and 
the  glenoid  ligament,  by  a  long,  rounded  tendon,  which,  tra- 
versing the  shoulder-joint,  passes  over  the  head  of  the  humerus, 
and  down  the  groove  between  the  two  tuberosities.  The  tendon 
is  retained  in  the  groove  by  a  fibrous  bridge  derived  from  the 
capsule  of  the  joint,  and  connected  with  the  tendon  of  the 
pectoralis  major.  Divide  this  bridge,  and  see  that  the  synovial 
membrane  of  the  joint  is  reflected  round  the  tendon,  and  accom- 
panies it  for  about  two  inches  down  the  groove,  thus  forming  a 
synovial  fold.  The  object  of  this  is  to  facilitate  the  play  of  the 
tendon,  and  to  carry  little  arteries  (from  the  anterior  circum- 
flex) for  its  supply.  The  two  heads  unite  about  the  middle  of  the 
arm,  and  form  a  single  muscle,  which  terminates  on  a  strong  flat 
tendon  of  considerable  length  ;  this  dips  down  into  the  triangular 
space  at  the  bend  of  the  elbow,  and,  after  a  slight  twist  upon  itself, 
is  inserted  into  the  posterior  part  of  the  tubercle  of  the  radius. 
The  anterior  part  of  the  tubercle,  over  which  the  tendon  plays,  is 
crusted  with  cartilage,  and  a  bursa  intervenes  to  diminish  friction. 
The  most  internal  fibres  of  the  muscle  are  inserted  into  a  strong 
broad  aponeurosis.  which  is  prolonged  from  the  inner  border  of 
the  tendon  to  the  fascia  on  the  inner  side  of  the  forearm.  This 
aponeurosis,  called  the  semi-lunar  fascia  of  the  biceps,  protects 
the  brachial  vessels  and  the  median  nerve  at  the  bend  of  the 
elbow. 

The  action  of  the  biceps  is  twofold.  1.  It  is  a  flexor  of  the 
forearm.  2.  It  is  a  powerful  supinator  of  the  forearm,  in  conse- 
quence of  its  insertion  into  the  posterior  part  of  the  tubercle  of 
the  radius.  Its  power  of  supination  is  greatest  when  the  forearm 


MUSCLES    OF    THE    ARM.  277 

is  half  bent,  because  its  tendon  is  then  inserted  at  a  right  angle. 
Why  does  the  long  tendon  pass  through  the  shoulder-joint  ?  It 
acts  like  a  strap,  and  confines  the  head  of  the  humerus  in  its  proper 
centre  of  motion.  But  for  this  tendon,  the  head  of  the  bone,  when 
the  deltoid  acts,  would  be  pulled  directly  upwards  and  strike 
against  the  under  surface  of  the  acromion.  When  the  tendon  is 
ruptured,  or  dislocated  from  its  groove,  a  man  can  move  his  arm 
backwards  and  forwards,  but  he  cannot  raise  the  smallest  weight.* 
The  biceps  is  supplied  with  blood  by  a  branch  from  the  brachial, 
which  runs  into  the  middle  of  its  inner  side  and  divides  into 
ascending  and  descending  branches.  Its  nerve  comes  from  the 
musculo-cutaneous. 

COBACO-BBA-  This  thin  muscle  is  situated  at  the  upper  part 

CHIAIIS.  of  the  arm,  and  runs  parallel  to  the  inner  border 

of  the  short  head  of  the  biceps.  It  arises  by  fleshy  fibres  from  the 
point  of  the  coracoid  process,  in  common  with  the  short  head  of 
the  biceps,  and  from  a  fibrous  septum  which  lies  between  them. 
The  muscle  terminates  on  a  flat  tendon,  which  is  inserted  into  the 
inner  side  of  the  middle  of  the  humerus,  between  the  brachialis 
anticus  and  the  inner  head  of  the  triceps.  Its  action  is  to  draw 
the  humerus  forwards  and  inwards — e.g.  in  bringing  the  gun  up  to 
the  shoulder.  It  is  supplied  by  a  branch  from  the  musculo-cuta- 
neous nerve  which  passes  through  it. 

Concerning  the  coraco-brachialis  remember,  1 .  That  the  mus- 
culo-cutaneous nerve  runs  through  it;  2.  That  its  inner  fleshy 
border  is  the  guide  to  the  axillary  artery  in  the  last  part  of  its 
course ;  3.  That  the  brachial  artery  lies  upon  its  flat  tendon  of 
insertion,  and  can  here  be  effectually  compressed  by  the  finger  or 
the  tourniquet. 

The  coraco-brachialis  and  biceps  are  covered  at  their  upper 
part  by  the  deltoid  and  pectoralis  major.  The  head  of  the 
humerus  rolls  beneath  the  coraco-brachialis  and  short  origin  of 
the  biceps ;  and  a  large  bursa  is  interposed  between  these  muscles 
and  the  tendon  of  the  subscapularis,  which  covers  the  head  of  the 
bone. 

*  See  a  preparation  in  the  Museum  of  St.  Bartholomew's  Hospital,  ser.  v.  9. 


278  BRACHIAL   ARTERY. 

BRACHIALIS  This  muscle  is  situated  upon  the  lower  half  of 

ANTICUS.  the   humerus,  and  is  partially  concealed   by  the 

biceps.     Between  the  two  muscles  is  the  musculo-cutaneous  nerve, 
which  supplies  them  both. 

It  arises  from  the  humerus  by  a  fleshy  digitation  on  either  side 
of  the  tendon  of  the  deltoid  ;  from  the  lower  half  of  the  front  sur- 
face of  the  bone,  and  from  the  intermuscular  septa.  The  muscle, 
becoming  thicker  and  broader,  covers  the  front  of  the  capsule  of  the 
elbow-joint  to  which  it  is  more  or  less  attached,  and  terminates 
on  a  tendon,  which  is  inserted  in  a  pointed  manner  into  the  coro- 
noid  process  of  the  ulna.  Its  action  is  to  bend  the  forearm.  Its 
nerves  come  from  the  musculo-cutaneous.  Sometimes  the  brachialis 
anticus  receives  in  addition  a  small  branch  from  the  musculo- 
spiral. 

Now  examine  the  course  and  relations  of  the  brachial  vessels 
and  nerves. 

COURSE  AND  BE-  The  brachial  artery — the  continuation  of  the 
LATIOXS  OF  THE  axillary — takes  its  name  at  the  lower  border  of 
BRACHIAL  ARTERY.  ^]ie  teres  major.  It  runs  down  the  inner  side  of 
the  arm,  along  the  inner  border  of  the  coraco-brachialis  and 
biceps,  to  about  an  inch  below  the  elbow,  where  it  divides,  near 
the  coronoid  process  of  the  ulna,  into  the  radial  and  ulnar 
arteries. 

Thus  its  direction  corresponds  with  a  line  drawn  from  the 
deepest  part  of  the  axilla  to  the  middle  point  between  the  condyles 
of  the  humerus. 

In  the  upper  part  of  its  course  it  lies  on  the  long  and  inner 
heads  of  the  triceps  (from  the  long  head  it  is  separated  by  the 
musculo-spiral  nerve  and  superior  profunda  artery) ;  in  the  middle, 
it  lies  on  the  tendon  of  the  coraco-brachialis ;  in  the  lower  part,  on 
the  brachialis  anticus. 

The  artery  is  accompanied  by  two  veins  (vence  comites\  and 
the  median  nerve,  all  of  which  are  invested  in  a  common  sheath 
of  fascia.  The  median  nerve  crosses  obliquely  in  front  of  the 
artery,  lying,  near  the  axilla,  on  its  outer  side ;  near  the  elbow,  on 
its  inner. 


BEACHIAL    AETEEY.  279 

The  ulnar  nerve  runs  along  the  inner  side  of  the  artery  as  far 
as  the  middle  of  the  arm.  Below  this  point,  the  nerve  leaves  the 
artery,  and  passes  through  the  interamscular  septum  to  get  behind 
the  internal  condyle. 

Superficial  to  the  artery,  are  the  internal  cutaneous  nerve  and 
the  basilic  vein. 

The  artery  is  more  or  less  overlapped,  in  the  first  part  of  its 
course,  by  the  coraco-brachialis,  lower  down  by  the  fleshy  belly  of 
the  biceps  ;  the  inner  borders  of  these  muscles,  in  their  respective 
situations,  being  the  best  guides  to  the  artery. 

About  the  middle  of  the  humerus,  the  artery  lies  for  nearly 
two  inches  on  the  tendon  of  the  coraco-brachialis,  and  is  so  close 
to  the  bone  that  it  can  be  effectually  compressed,  provided  the 
pressure  be  made  in  the  proper  direction — namely,  outwards ;  here, 
too,  it  is  crossed  by  the  median  nerve. 

At  the  bend  of  the  elbow  the  artery  is  crossed  by  the  semi- 
lunar  fascia  from  the  biceps.  It  enters  a  triangular  space, 
bounded  by  the  pronator  radii  teres  internally,  and  by  the 
supinator  radii  longus  externally.  It  sinks  into  this  space,  with 
the  tendon  of  the  biceps  to  its  outer  side,  and  the  median  nerve  to 
its  inner  ;  all  three  rest  upon  the  brachialis  anticus.  To  compress 
the  artery  here,  pressure  should  be  made  directly  backwards. 
Opposite  the  coronoid  process  of  the  ulna  it  divides  into  the  radial 
and  ulnar  arteries. 

Two  veins,  of  which  the  internal  is  the  larger,  lie  in  close 
contact  with  the  brachial  artery,  and  communicate  at  frequent 
intervals  by  transrerse  branches.  Near  the  axilla  they  join  and 
form  the  axillary  vein. 

BEANCHES  OF  The  brachial  artery  gives  off  three  branches, 

BRACHIAL  AETEET.  all  from  its  inner  side  :  namely,  the  superior 
profunda,  the  inferior  profunda,  and  the  anastomotica  magna. 
It  also  distributes  muscular  branches  (to  the  coraco-brachialis 
and  biceps),  which  are  given  off  from  its  outer  side. 

a.  The  profunda  superior  arises  from  the  brachial  artery,  immedi- 
ately below  the  tendon  of  the  teres  major.*     It  winds  round  the  hack  of 
*  If  the  profunda  be  not  in  its  usual  plao'e,  look  for  it  above  the  tendon  of  the 


280 


BEACHIAL    ARTEKY. 


the  humerus,  between  the  outer  and  inner  heads  of  the  triceps,  accom- 
panied by  the  musculo-spiral  nerve,  and,  a  little  above  the  middle 
of  the  arm,  divides  into  two  branches,  which  run  for  some  distance  on 
either  side  of  the  nerve.  One  of  these  runs  in  the  substance  of  the 

FIG.  57. 


Eaperior  profunda    .    .    .    . 


Interosseous  recurrent    .    . 


Hadial  recurrent 


Posterior  interosseous .    .    . 


Inferior  profnnda. 

Anastomotica  magna. 

Anterior  ulnar  recurrent. 
Posterior  ulnar  recurrent. 

Common  interosseous. 
Anterior  interosseous. 


PLAN    OF   THE    CHIEF   BRANCHES   OF    THE    BRACHIAL    AETEHY    AND    THE   ABTEEIAL 
INOSCULATIONS   ABOUT   THE    BIGHT    ELBOW-JOINT. 

triceps  muscle,  with  the  nerve  to  the  anconeus,  as  far  as  the  olecranon, 
and  anastomoses  with  the  posterior  ulnar  recurrent,  the  interosseous  re- 
current, and  anastomotica  magna  arteries  :  the  other  branch  accompanies 

latissimus  dor*i,  where  it  will  probably  be  given  off  from  a  common  trunk  -with  the 
posterior  circumflex. 


BEACHIAL    ARTERY.  281 

the  mus3ulo-spiral  nerve  to  the  outer  side  of  the  arm,  where  it  perforates 
the  external  inter  muscular  septum.  It  then  descends  deep  in  the  fissure 
between  the  brachialis  anticus  and  supinator  radii  longus,  and  terminates 
in  numerous  ramifications,  some  of  which  pass  in  front  of  the  external 
condyle,  others  behind  it,  to  inosculate  with  the  radial  and  inter- 
osseous  recurrent  arteries. 

Before  its  division,  the  superior  profunda  sends  several  branches  to 
the  triceps,  some  of  which  inosculate  with  the  circumflex.  These  assist 
in  establishing  a  collateral  circulation  when  the  brachial  artery  is  ligatured 
above  the  origin  of  the  profunda. 

b.  The  profunda  inferior  arises  from  the  brachial,  opposite  to  the  in- 
sertion of  the  coraco-brachialis,  or  sometimes  by  a  common  trunk  with 
the  superior  profunda.       It  runs  with  the  ulnar  nerve   on   the  inner 
head  of  the  triceps  (which  it  supplies),  passes  through  the  internal  inter- 
muscular  septum,  and  then  descends  to  the  interval  between  the  internal 
condyle  and  the  olecranon,  inosculating  with  the  posterior  ulnar  recurrent 
and  anastomotica  magna  arteries. 

The  nutrient  artery  of  the  humerus  arises  sometimes  from  the  brachial, 
sometimes  from  the  interior  profunda.  It  pierces  the  tendon  of  the 
coraco-brachialis,  runs  obliquely  downwards  through  the  bone,  and  in  the 
medullary  canal  divides  into  ascending  and  descending  branches,  which 
anastomose  with  the  nutrient  vessels  of  the  bone  derived  from  the  peri- 
osteum. 

c.  The  anastomotica  magna  arises  from  the  inner  side  of  the  brachial, 
about  two  inches  above  the  elbow,  runs  tortuously  inwards  across  the 
brachialis  anticus,  and  divides  into  branches,  some  of  which  pass  in  front 
of  the  internal  condyle,  anastomosing  with  the  anterior  ulnar  recurrent 
artery;  others  pass  behind  the  internal  condyle  and  anastomose  with  the 
inferior  profunda  and  posterior  ulnar  recurrent  arteries;  and  one  branch 
forms  an  arch,  above  the  olecranon  fossa,  with  the  superior  profunda. 

d.  Numerous  muscular  branches  arise  from  the  outer  side  of  the 
brachial  artery ;  one  of  these,  the  bicipital,  more  constant  than  the  rest, 
supplies   the   biceps ;    another   runs   transversely   beneath   the  coraco- 
brachialis  and  biceps,  over  the  insertion  of  the  deltoid,  supplying  this 
muscle  and  the  brachialis  anticus. 

The  two  veins  which  accompany  the  brachial 

artery  are  continuations  of  the  deep  radial  and 

ulnar  veins.     The  internal  is  usually  the  larger,  and  generally 

receives  the  veins  corresponding  to  the  principa    branches  of  the 


282  NEEVES    OF    THE    UPPEE    AEM. 

artery.  In  their  course  they  are  connected  at  intervals  by  trans- 
verse branches  either  in  front  of,  or  behind  the  artery.  Near  the 
subscapularis,  the  vena  comes  externa  crosses  obliquely  in  front  of 
the  axillary  artery  to  join  the  vena  comes  internet,,  which  then 
takes  the  name  of  axillary. 

Now  trace  the  great  nerves  of  the  upper  arm,  which  proceed 
from  the  brachial  plexus  near  the  tendon  of  the  subscapularis  : 
namely,  the  median,  the  musculo-cutaneous,  the  ulnar,  and  the 
musculo-spiral  or  radial. 

The  median  nerve  arises  by  two  roots,  which 

MEDIAN  NERVE.  -  -     ,  M1  /       «<?,i\ 

converge  in  tront  ot  the  axillary  artery  (p.  2b4). 

The  external  root  is  derived  from  a  trunk  in  common  with  the 
musculo-cutaneous ;  the  internal  from  a  trunk  in  common  with 
the  ulnar  and  internal  cutaneous.  In  its  course  down  the  arm, 
the  nerve  is  situated  at  first  on  the  outer  side  of  the  brachial 
artery,  between  it  and  the  coraco-brachialis  ;  about  the  middle  of 
the  arm  the  nerve  crosses  obliquely  over  (in  some  cases  under)  the 
vessel,  so  that  at  the  bend  of  the  elbow  it  is  found  on  the  inner 
side  of  the  artery,  lying  upon  the  brachialis  anticus,  and  covered 
by  the  semilunar  fascia  from  the  biceps.* 

*  I  hare  observed  the  following  varieties  relating  to  the  median  nerve,  and  its 
course  in  regard  to  the  artery. 

a.  The  roots  may  be  increased  in  number  by  one  on  either  side  of  the  artery  ;  or 
the  internal  root  may  be  deficient. 

b.  They  may  vary  in  their  position  with  regard  to  the  artery ;  both  may  be  situa- 
ted behind  the  vessel,  or  one  behind,  and  the  other  in  front  of  it. 

c.  The  nerve,  formed  in  the  usual  manner,  may  be  joined  lower  down  by  a  large 
branch  from  the  external  cutaneous ;  such  a  case  presents  a  junction  of  two  large 
nerves  in  front  of  the  brachial  artery,  in  the  middle  of  the  arm. 

d.  The  nerve  in  many  cases  crosses  under,  instead  of  over  the  artery. 

e.  The  nerve  sometimes  runs  parallel  and  external  to  the  artery;  or  it  may  run 
parallel  to,  and  in  front  of,  the  artery. 

In  one  hundred  arms  the  relative  position  of  the  nerve  to  the  artery  in  its  course 
down  the  arm  was  as  follows : — 

In  72,  the  nerve  took  the  ordinary  course. 
„  20,  the  nerve  crossed  obliquely  under  the  artery. 
„    5,  the  nerve  ran  parallel  and  superficial  to  the  artery. 
,.    3,  the  nerve  ran  parallel  and  external  to  the  artery. 

These  varieties  of  the  median  nerve  are  of  practical  importance,  for  this  reason: 


NERVES    OF    THE    UPPER    ARM.  283 

As  a  summary  of  the  distribution  of  the  median  nerve,  we  may 
say  that  it  supplies  the  two  pronators  and  all  the  flexors  of  the 
forearm  (except  the  flexor  carpi  ulnaris  and  the  ulnar  half  of  the 
flexor  profundus  digitorum)  ;  the  muscles  of  the  ball  of  the  thumb, 
the  two  radial  lumbricales,  both  sides  of  the  thumb,  fore  and 
middle  fingers,  and  the  radial  side  of  the  ring  finger. 

MUSCUT.O-CUTA-  This  nerve  (often  called  the  external  cutaneous) 
NEOUS  NERVE,  arises  in  common  with  the  external  root  of  the 
median  from  the  external  cord  of  the  brachial  plexus  behind  the 
pectoralis  minor,  and  is  situated  on  the  outer  side  of  the  axillary 
artery.  It  perforates  the  coraco-brachialis  obliquely,  and  then 
runs  down  between  the  biceps  and  the  brachialis  anticus.  A  little 
above  the  elbow-joint,  between  the  tendon  of  the  biceps  and  the 
supinator  radii  longus,  the  nerve  becomes  subcutaneous,  and,  pass- 
ing under  the  median  cephalic  vein,  divides  into  branches,  for  the 
supply  of  the  integuments  of  the  forearm. 

The  musculo-cutaneous  nerve,  in  the  upper  part  of  its  course, 
sends  branches  to  the  coraco-brachialis  and  the  short  head  of  the 
biceps,  and,  as  it  descends  between  the  biceps  and  the  brachialis 
anticus,  it  supplies  both.  Consequently,  if  the  nerve  were  divided 
in  the  axilla,  the  result  would  be  inability  to  bend  the  arm.*  This 
nerve  also  sends  small  filaments  to  supply  the  elbow-joint. 

This  nerve  arises  from  the  inner  cord  of  the 

brachial   plexus,    in    common   with    the    internal 

cutaneous  and  the  inner  head  of  the  median.     It  descends  along 

the  inner  side  of  the  brachial  artery,  as  far  as  the  insertion  of  the 

whenever,  in  the  operation  of  tying  the  brachial  artery,  we  do  not  find  the  nerve  in 
its  normal  position,  we  may  expect  to  find  some  irregular  distribution  of  the  arteries — 
e.g.  a  high  division  of  the  brachial,  or  even,  which  I  have  often  seen,  a  '  vas  aberrans ' 
coming  from  the  upper  part  of  the  brachial,  and  joining  either  the  radial  or  ulnar 
arteries. 

*  In  some  instances  the  musculo-cutaneous  nerve  descends  on  the  inner  side  of  the 
coraco-brachialis  without  perforating  the  muscle  ;  in  these  cases  it  often  sends  a  larger 
branch  than  usual  to  the  median  nerve. 

The  trunk  of  the  musculo-cutaneous  nerve  may  come  from  the  median  at  any  point 
between  the  axilla  and  the  middle  of  the  arm.  In  some  subjects  the  nerve  is  absent ; 
all  its  branches  are  then  supplied  )  y  the  median,  which  is  larger  than  usual.  Such 
anomalies  are  easily  explained  by  the  fact  of  the  two  nerves  having  a  common  origin. 


284  NERVES    OF    THE    UPPEE   ARM. 

coraco-brachialis.  The  nerve  then  diverges  from  the  artery,  per- 
forates the  internal  intermuscular  septum,  and  runs  with  the  in- 
ferior profunda  artery,  behind  the  internal  condyle. 

The  distribution  of  the  nerve  is  to  the  flexor  carpi  ulnaris,  to 
half  the  flexor  profundus  digitorum,  to  all  the  interosseous  muscles 
of  the  hand,  to  both  sides  of  the  little  finger,  to  the  ulnar  side  of 
the  ring  finger,  to  the  muscles  of  the  ball  of  the  little  finger,  to 
the  two  ulnar  lumbricales,  and,  lastly,  to  the  adductor  pollicis, 
and  the  inner  head  of  the  flexor  brevis  pollicis. 

Previous  to  the  examination  of  the  musculo-spiral  nerve,  we 
should  examine  the  great  muscle  which  occupies  the  whole  of  the 
posterior  part  of  the  humerus — viz.  the  triceps  extensor  cubiti. 

TRICEPS  EXTEN-         This  muscle  has  three  distinct  origins,  named 
SOE  CuBin.  from  their  position,  the  external,  the  internal,  and 

the  middle  or  long  heads  (p.  266).  The  middle  or  long  head  arises 
by  a  flat  tendon  from  the  inferior  border  of  the  scapula,  close  to 
the  glenoid  cavity.  The  external  head  arises  from  the  humerus, 
beginning  in  a  pointed  form  immediately  below  the  insertion  of 
the  teres  minor,  and  extending  as  low  down  as  the  musculo-spiral 
groove.  The  internal  head  arises  from  the  humerus  below  the 
insertion  of  the  teres  major,  from  the  posterior  surface  of  the  bone 
below  the  musculo-spiral  groove,  and  from  the  internal  inter- 
muscular  septum.  The  three  heads  unite,  near  the  middle  of  the 
arm,  to  form  a  single  fleshy  mass,  which  covers  the  posterior  part 
of  the  elbow-joint,  and  is  inserted  by  a  thick  tendon  into  the 
summit  and  sides  of  the  olecranon.  Each  head  is  supplied  by  a 
separate  branch  from  the  musculo-spiral  nerve. 

MUSCULO-SPI-  This,  the  largest  of  the  brachial  nerves,  arises, 

EAL  NEETE.  in  common  with  the  circumflex,  from  the  posterior 

cord  of  the  axillary  plexus  (p.  268).  It  descends  at  first  behind  the 
axillary  artery,  and  then  winds  obliquely  round  the  posterior  part 
of  the  humerus,  between  the  external  and  internal  heads  of  the 
triceps,  in  company  with  the  superior  profunda  artery.  About  the 
lower  third  of  the  outer  side  of  the  arm,  the  nerve  perforates  the 
external  intermuscular  septum,  and  then  runs  deeply  embedded 
between  the  brachialis  anticus  and  the  supinator  radii  longus. 


DISSECTION    OF    THE    FOREARM.  285 

The  nerve  gives  off  branches  on  the  inner  side  of  the  humerus, 
to  the  inner  and  long  heads  of  the  triceps  ;  on  the  back  of  the 
humerus,  to  the  external  head  of  the  triceps  and  the  anconeus ;  on 
the  outer  side  of  the  humerus,  to  the  supinator  radii  longus,  the 
extensor  carpi  radialis  longior,  and  the  brachialis  anticus  (some- 
times) ;  lastly,  after  perforating  the  septum,  it  gives  off  the  upper 
and  lower  external  cutaneous  branches. 

A  little  above  the  elbow-joint  the  nerve  divides  into  its  two 
principal  branches — the  radial,  which  accompanies  the  radial 
artery  along  the  forearm — and  the  posterior  interosseous,  which 
perforates  the  supinator  brevis,  and  supplies  the  muscles  on  the 
back  of  the  forearm. 

To  sum  up  the  muscular  distribution  of  this  great  nerve,  we 
may  say  that  it  supplies  all  the  extensors  of  the  forearm,  wrist, 
thumb,  and  fingers  ;  and  all  the  supinators  except  one — namely, 
the  biceps  (supplied  by  the  musculo-cutaneous  nerve). 


DISSECTION   OF   THE   FKONT   OF    THE  FOREARM. 

Prolong  the  incision  down  to  the  wrist,  and,  at 
its  termination,  make  another  transversely.     Ee- 
flect  the  skin,  and  dissect  the  subcutaneous  veins  and  nerves. 

CUTANEOUS  On  the  inner  side  is  the  anterior  ulnar  vein, 

VEINS.  which  commences  on  the  front  of  the  wrist,  and 

is  then  continued  upwards  on  the  inner  side  of  the  forearm  as  far 
as  the  elbow,  where  it  is  joined  by  the  posterior  ulnar  vein  to  form 
the  basilic  (p.  273). 

The  veins  on  the  back  of  the  hand  commence  at  the  extremi- 
ties of  the  fingers,  run  up  betiveen  the  knuckles,  and  unite  on  the 
back  of  the  hand,  forming  an  arch,  with  its  concavity  upwards. 
The  posterior  ulnar  vein  arises  from  this  arch  by  a  branch 
(vena  salvatella)  situated  over  the  fourth  interosseous  space,  and 
runs  up  on  the  back  of  the  forearm  towards  the  inner  condyle,  to 
join  the  anterior  ulnar  vein. 

The  radial  vein,  situated  on  the  outer  side  of  the  forearm, 


286  FASCIA  OP  THE  FOREAEM. 

commences  on  the  back  of  the  hand  from  the  venous  arch,  runs 
up  the  outer  side  of  the  front  of  the  forearm  to  the  elbow,  where 
it  becomes  the  cephalic. 

Running  up  in  front  of  the  middle  of  the  forearm  is  the  median 
vein  ;  near  the  bend  of  the  elbow  it  is  joined  by  a  deep  branch — 
mediana  pro/undo, — after  which  it  divides  into  two  branches,  an 
outer  or  median  cephalic,  which  joins  the  cephalic,  and  an  inner 
or  median  basilic,  which  joins  the  basilic  (fig.  56). 

CUTANEOUS  On  the  radial  side  of  the  forearm,  as  low  down 

NEKVES.  as  the  wrist,  are  found  the  terminal  filaments  of 

the  anterior  branch  of  the  musculo-cutaneous  nerve,  which,  about 
the  middle  of  the  forearm,  sends  a  branch  backwards  to  supply  the 
posterior  and  lower  part  of  the  forearm  as  low  as  the  wrist,  commu- 
nicating with  the  radial  and  external  cutaneous  branch  of  the 
musculo-spiral.  At  the  lower  part  of  the  forearm,  one  or  more 
of  these  filaments  are  situated  over  the  radial  artery. 

In  front  of  the  upper  part  of  the  forearm  are  some  filaments 
of  the  external  cutaneous  branch  of  the  musculo-spiral  nerve ;  on 
the  outer  and  back  part  of  the  forearm,  near  the  elbow,  the  lower 
external  cutaneous  branch  of  the  musculo-spiral  runs  down  as  far 
as  the  wrist  to  supply  the  skin. 

At  the  lower  third  of  the  radial  side  of  the  forearm,  the  radial 
nerve  becomes  superficial,  and  turns  over  the  radius  to  supply  the 
back  of  the  hand  and  fingers. 

On  the  ulnar  side  the  anterior  division  of  the  internal  cuta- 
neous nerve  descends  as  far  as  the  wrist ;  its  posterior  branch 
passing  to  the  back  of  the  forearm  to  supply  it  as  far  as  the  middle. 
Near  the  styloid  process  of  the  ulna,  the  dorsal  branch  of  the 
ulnar  nerve  perforates  the  fascia  to  reach  the  back  of  the  hand. 

DEEP  FASCIA  OF  The  muscles  of  the  forearm  are  enveloped  by  a 
THE  FOREARM.  dense  shining  aponeurosis,  continuous  with  that 
of  the  arm.  Its  thickness  increases  towards  the  wrist,  that 
the  tendons,  in  this  situation,  may  be  kept  in  their  position.  It 
is  composed  of  fibres  which  cross  each  other  obliquely,  and  is 
attached,  above,  to  the  condyles  of  the  humerus  and  olecranon ; 
internally,  to  the  ridge  on  the  posterior  part  of  the  ulna.  At  the 


MUSCLES    OF    THE    FOREARM.  287 

back  of  the  wrist,  it  forms  the  posterior  annular  ligament,  and  in 
front,  it  is  continuous  with  the  anterior  annular  ligament.  Above, 
the  fascia  is  strengthened  by  fibres  from  the  tendons  of  the  biceps 
and  brachialis  anticus.  The  aponeurotic  expansion  from  the  inner 
edge  of  the  tendon  of  the  biceps  is  exceedingly  strong.  It  braces 
the  muscles  on  the  inner  side  of  the  forearm,  and  interlaces  at 
right  angles  with  the  fibres  of  the  fascia  attached  to  the  internal 
condyle.  The  under  surface  of  the  fascia  gives  origin  to  the  mus- 
cular fibres  in  the  upper  part  of  the  forearm,  and  furnishes  septa 
which  separate  the  muscles,  and  form  surfaces  for  their  origin. 
The  fascia  is  perforated  at  various  parts  for  the  passage  of  the 
cutaneous  vessels  and  nerves  of  the  forearm. 

Eemove  the  fascia  from  the  muscles  by  incisions 
corresponding   to  those    for   reflecting  the  skin  ; 
taking  care  of  the  cutaneous  branches  of  the  median  and  ulnar 
nerves  close  to  the  wrist. 

TKIANGLE  AT  At  the  bend  of  the  elbow  is  a  triangular  space, 

THE  ELBOW.  with  its  base  towards  the  humerus  ;  on  the  inner 

side  this  space  is  bounded  by  the  pronator  teres  ;  on  the  outer,  by 
the  supinator  radii  longus.  In  it  are  the  following  objects,  which 
must  be  carefully  dissected  : — 1.  In  the  centre  is  the  brachial 
artery  (with  its  companion  veins)  dividing  into  the  radial  and 
ulnar ;  2,  on  the  outer  side  of  the  artery  is  the  tendon  of  the 
biceps  ;  3,  on  the  inner  side  is  the  median  nerve ;  4,  the  musculo- 
spiral  nerve  is  partly  concealed  by  the  supinator  longus ;  5,  the 
radial  recurrent  artery ;  6,  the  anterior  ulnar  recurrent ;  7,  the 
common  interosseous  branch  of  the  ulnar  artery;  8,  the  vena 
mediana  profunda. 

MUSCLES  OF  The  muscles  of  the  forearm  are  arranged  in  two 

THE  FOREARM.  groups  ;  one,  consisting  of  supinators  and  exten- 
sors, is  attached  to  the  outer  condyloid  ridge  and  condyle ;  the 
other,  consisting  of  pronators  and  flexors,  is  attached  to  the  inner 
condyle.  The  inner  group  should  be  examined  first.  They  arise 
by  a  common  tendon,  and  are  arranged  in  the  following  order : 
pronator  teres ;  flexor  carpi  radialis ;  palmaris  longus ;  flexor 
carpi  ulnaris,  and  flexor  sublimis  digitorum. 


288  MUSCLES   OF    THE    FOREARM. 

PBONATOR  This  muscle  forms  the  inner  boundary  of  the 

EADH  TEKES.  triangular  space  at  the  elbow.     It  arises  from  the 

anterior  surface  of  the  internal  condyle,  from  the  common  tendon, 
from  the  fascia  of  the  forearm,  and  from  the  septum  between  it 
and  the  flexor  carpi  radialis.  It  has  also  a  small  tendinous  origin 
from  the  inner  border  of  the  coronoid  process  of  the  ulna.  From 
these  two  origins,  between  which  the  median  nerve  passes,  the 
muscle  proceeds  obliquely  downwards,  and  is  inserted  by  a  flat 
tendon  into  a  rough  surface  on  the  outer  and  back  part  of  the 
middle  third  of  the  radius.  In  amputating  the  forearm,  it  is  very 
desirable  to  save  the  insertion  of  this  muscle,  that  the  stump  may 
have  a  pronator.  Its  nerve  comes  from  the  median. 

FLEXOR  CARPI          This  muscle  arises  by  the  common  tendon  from 
EADIALIS.  the  internal  condyle,  from  the  intermuscular  septa, 

and  from  the  fascia  of  the  forearm.  The  fleshy  fibres  terminate 
near  the  middle  of  the  forearm,  in  a  flat  tendon,  which  runs  in  a 
separate  sheath  outside  the  anterior  annular  ligament  of  the  wrist, 
passes  through  a  groove  in  the  os  trapezium,  bridged  over  by 
fibrous  tissue  and  lined  by  a  synovial  membrane,  and  is  inserted 
into  the  base  of  the  second  metacarpal  bone.  The  outer  border  of 
its  tendon  is  the  guide  to  the  radial  artery  in  the  lower  half  of  the 
forearm.  Its  nerve  comes  from  the  median. 

PALMARIS  This  slender  muscle  arises  from  the  common 

LONGUS.  tendon  at  the  internal  condyle,  from  the  inter- 

muscular  septa,  and  from  the  fascia  of  the  forearm.  About  the 
middle  of  the  forearm  it  terminates  in  a  flat  tendon,  which  de- 
scends along  the  middle  of  the  forearm  to  the  wrist,  lying  upon 
the  flexor  sublimis  digitorum ;  it  then  passes  over  the  anterior 
annular  ligament,  and  is  continued  into  the  palmar  fascia.  This 
muscle  is  a  tensor  of  the  palmar  fascia.*  Its  nerve  comes  from 
the  median. 

FLEXOE  CABPI  This  muscle  arises  by  two  heads :  one  from  the 

ULNARIS.  internal   condyle,  the  common   tendon,  and  the 

*  The  palmaris  longus  is  absent  in  about  one  out  of  ten  subjects.  The  situation 
of  its  muscular  portion  is  subject  to  variety ;  sometimes  occupying  the  middle,  some- 
times the  lower  third  of  the  forearm.  The  tendon  is  in  some  instances  wholly  inserted 
into  the  anterior  annular  ligament. 


MUSCLES    OP   THE    FOEEAEM.  289 

intermuscular  septum ;  the  other  from  the  inner  edge  of  the 
olecranon :  these  two  origins  form  an  arch,  under  which  the  ulnar 
nerve  passes.  It  also  arises  from  the  upper  two-thirds  of  the 
posterior  edge  of  the  ulna,  through  the  medium  of  the  aponeurosis, 
which  is  common  to  this  muscle  and  the  flexor  profundus  digi- 
torum.  The  tendon  appears  on  the  radial  side  of  the  muscle, 
about  the  lower  third  of  the  forearm,  and  receives  fleshy  fibres  on 
its  ulnar  side  as  low  as  the  wrist.  It  is  inserted  into  the  os  pisi- 
forme,  and  thence  by  a  strong  tendon  into  the  os  unciforme  and 
the  base  of  the  fifth  metacarpal  bone.  Its  nerve  comes  from  the 
ulnar. 

The  tendon  of  the  flexor  carpi  ulnaris  is  the  guide  to  the  ulnar 
artery,  which  lies  close  to  its  radial  side,  and  is  overlapped  by  it. 
As  it  passes  over  the  annular  ligament,  the  tendon  furnishes  a 
fibrous  expansion  to  protect  the  ulnar  artery  and  nerve. 

FLEXOE  SUBLI-  This  muscle  is  situated  beneath  those  previously 
MIS  DIGITORUM.  mentioned,  and  has  two  distinct  origins.  The 
longer  origin  takes  place  from  the  internal  condyle,  from  the  in- 
ternal lateral  ligament,  the  common  tendon,  the  iutermuscular 
septa,  and  the  coronoid  process  of  the  ulna ;  the  shorter  origin 
takes  place  by  tendinous  and  fleshy  fibres  from  an  oblique  ridge  oil 
the  front  of  the  radius,  extending  from  the  tubercle  to  about  an 
inch  below  the  insertion  of  the  pronator  teres.  This,  called  its 
radial  origin,  is  partly  concealed  by  the  pronator  teres.  The 
muscle,  thus  formed,  passes  down  the  middle  of  the  forearm,  and 
divides  into  four  distinct  muscular  slips  :  from  these,  four  tendons 
arise,  which  pass  beneath  the  annular  ligament,  arranged  in  two 
pairs ;  the  tendons  of  the  middle  and  ring  fingers  being  placed 
over  those  of  the  fore  and  little  fingers.  The  tendons  pass  through 
the  palm  to  the  fingers,  where  they  split  to  allow  the  passage  of 
the  deep  flexor  tendons,  and  are  inserted  into  the  sides  of  the 
second  phalanges.  Its  action  is,  therefore,  to  bend  the  second 
joint  of  the  fingers. 

The  muscles  described  as  arising  from  the  internal  condyle  are 
all  supplied  by  the  median  nerve,  except  the  flexor  carpi  ulnaris, 
which  is  supplied  by  the  ulnar. 

u 


290  RADIAL   AETEEY. 

Having  finished  the  superficial  muscles  on  the  inner  side  of 
the  forearm,  notice  one  of  those  on  the  outer  side,  named 
supinator  radii  longus,  before  tracing  the  vessels  and  nerves  of  the 
forearm. 

SUPINATOR  This  muscle  forms  the  external  boundary  of  the 

EADH  LONGUS.  triangular  space  at  the  bend  of  the  elbow.  It 
arises  from  the  upper  two-thirds  of  the  external  condyloid  ridge 
of  the  humerus,  commencing  a  little  below  the  insertion  of  the 
deltoid,  and  from  the  external  intermuscular  septum.  The  mus- 
cular fibres  'terminate  about  the  middle  of  the  forearm  in  a  flat 
tendon,  which  is  inserted  into  the  outer  side  of  the  base  of  the 
styloid  process  of  the  radius.  The  inner  border  of  the  muscle  is 
the  guide  to  the  radial  artery.  It  supinates  the  hand,  but  acts 
much  more  powerfully  as  a  flexor  of  the  forearm.  It  is  supplied 
by  the  musculo- spiral  nerve. 

The  radial  artery,  the  smaller  division  of  the 
brachial,  runs  down  the  radial  side  of  the  forearm 
to  the  wrist,  where  it  turns  over  the  external  lateral  ligament  of 
the  carpus,  beneath  the  extensor  tendons  of  the  thumb,  and  sinks 
into  the  angle  between  the  first  and  second  metacarpal  bones  to 
form  the  deep  palmar  arch.  Thus,  its  course  corresponds  with  a 
line  drawn  from  the  middle  of  the  bend  of  the  elbow,  to  the  front 
of  the  styloid  process  of  the  radius. 

In  the  upper  third  of  the  forearm,  the  artery  lies  deep  between 
the  pronator  teres  on  the  inner  and  the  supinator  longus  on  the 
outer  side ;  the  fleshy  border  of  the  latter  overlaps  it  in  muscular 
subjects.  In  the  lower  two-thirds  of  the  forearm  the  artery  is 
more  superficial,  and  is  placed  between  the  tendons  of  the  supi- 
nator longus  on  the  outer  and  the  flexor  carpi  radialis  on  the  inner 
side.  In  its  course,  it  lies  successively  on  the  following  : — first, 
upon  the  tendon  of  the  biceps  ;  secondly,  upon  the  supinator  radii 
brevis ;  thirdly,  upon  the  insertion  of  the  pronator  teres ;  fourthly, 
upon  the  radial  origin  of  the  flexor  sublimis ;  fifthly,  upon  the 
flexor  longus  pollicis ;  sixthly,  upon  the  pronator  quadratus  and 
the  lower  end  of  the  radius.  The  artery  then  crosses  the  wrist  joint, 
lying  upon  the  external  lateral  ligament ;  next,  it  lies  upon  the 


RADIAL    ARTERY.  291 

trapezium  ;  and,  lastly,  passing  between  the  two  heads  of  the  first 
dorsal  interosseous  muscle,  it  enters  the  palm  to  form  the  deep 
palmar  arch.  It  is  accompanied  by  two  veins,  which  communicate 
at  frequent  intervals,  and  join  the  venae  comites  of  the  brachial 
artery  at  the  bend  of  the  elbow. 

In  the  middle  third  of  its  course  the  artery  is  accompanied  by 
the  radial  nerve  (a  branch  of  the  musculo-spiral),  which  lies  to  its 
outer  side.  Below  this  point,  the  nerve  leaves  the  artery,  and 
passes,  under  the  tendon  of  the  supinator  longus,  to  the  back  of 
the  hand. 

Thus,  in  the  situation  where  the  pulse  is  usually  felt,  the  radial 
nerve  no  longer  accompanies  the  artery  ;  nevertheless,  the  vessel 
is  not  without  a  nerve,  for  it  is  accompanied  by  a  branch  of  the 
musculo-cutaneous  (or  external  cutaneous),  which  lies  superficial 
to  it. 

The  radial  artery  sends  off  in  the  forearm  the  following 
branches,  besides  offsets,  which  supply  the  muscles  on  the  outer 
side  of  the  forearm. 

a.  The  radial  recurrent  is  given  off  just  below  the  elbow  ;  it  ascends 
to  supply  the  long  and  short  supinators  and  the  two  radial  extensors. 
One  of  its  ramifications  runs  up  with  the  musculo-spiral  nerve  between 
the  supinator  longus  and  brachialis  anticus,  and  forms  a  delicate  inoscula- 
tion with  the  superior  profunda  (p.  280). 

b.  The  arteria  superficialis  voice  arises  from  the  radial,  about  half  an 
inch,  or  more,  above  the  lower  end  of  the  radius  :  it  runs  over  the  an- 
terior annular  ligament,  above,  or  perhaps  through,  the  origin  of  the 
muscles  of  the  ball  of  the  thumb,  into  the  palm  of  the  hand,   where  it 
inosculates  with  the  superficial  branch  of  the  ulnar,  and  completes  the 
superficial  palmar  arch.* 

c.  The  anterior  carpal  artery  is  a  small  branch  of  the  radial,  which 
runs  beneath  the  tendons,  and  supplies  the  anterior  surface  of  the  synovial 
membrane  and  bones  of  the  carpus,  anastomosing  with  the  anterior  inter- 
osseous,  the  anterior  carpal  branch  of  the  ulnar,  and  the  recurrent  carpal 
branch  of  the  deep  palmar  arch. 

*  There  is  great  variety  in  the  size  and  origin  of  the  superficialis  volae ;  some- 
times it  is  very  large,  arises  higher  than  usual,  and  runs  to  the  wrist  parallel  with 
the  radial ;  sometimes  it  is  very  small,  terminating  in  the  muscles  of  the  thumb ;  or 
it  may  be  absent. 

TJ  2 


292  ULNAE   AETEEY. 

d.  The  posterior  carpal  artery  runs  beneath  the  extensor  tendons,  and 
joins  the  corresponding  branch  of  the  ulnar  to  form  an  arch ;  it  also 
anastomoses  with  the  anterior  interosseous  artery  on  the  back  of  the  wrist. 

e.  Small  muscular  branches  are  also  given  off  by  the  radial  artery  in 
its  course  down,  the  forearm. 

The   radial  nerve,  a  branch  of  the   musculo- 

EADIAL  NERVE.  .',.-.  ~     ,  ,11        i      f    .-,        „ 

spiral,  is  given  on  above  the  bend  of  the  elbow, 

deep  between  the  supinator  radii  longus  and  brachialis  anticus ;  it 
descends  on  the  outer  side  of  the  radial  artery,  covered  by  the 
supinator  radii  longus.  In  the  upper  third  of  the  forearm  the 
nerve  is  at  some  distance  from  the  artery  ;  in  the  middle  third  it 
approaches  nearer  to  it,  lying  to  its  outer  side  ;  but  in  the  lower 
third,  the  nerve  leaves  the  artery,  passes  underneath  the  tendon 
of  the  supinator  longus,  perforates  the  fascia  on  the  outer  side  of 
the  forearm,  and  becomes  subcutaneous.  It  then  divides  into  two 
branches  ;  an  outer,  which  supplies  the  skin  of  the  ball  of  the 
thumb,  and  communicates  with  the  musculo-cutaneous  nerve ;  and 
an  inner,  which  generally  supplies  both  sides  of  the  dorsal  aspects 
of  the  thumb,  of  the  index  and  middle  fingers,  and  of  the  radial 
side  of  the  ring  finger. 

This  artery,  the  larger  of  the  two  divisions  of 
the  brachial,  comes  off  at  the  middle  of  the  elbow, 
runs  obliquely  inwards  along  the  ulnar  side  of  the  forearm  to  the 
wrist,  passes  over  the  annular  ligament  near  the  pisiform  bone, 
and  entering  the  palm,  forms  the  superficial  palmar  arch,  by 
inosculating  with  the  superficialis  volse. 

In  the  upper  half  of  its  course  the  artery  describes  a  gentle 
curve  with  the  concavity  towards  the  radius,  and  lies  deep  beneath 
the  superficial  layer  of  muscles,  namely,  the  pronator  teres,  flexor 
carpi  radialis,  palmaris  longus,  and  flexor  sublimis  digitorum.  It 
is  also  crossed  in  its  upper  part  by  the  median  nerve.  In  the 
lower  part  of  its  course  it  comes  nearer  the  surface,  and  descends 
between  the  flexor  sublimis  and  flexor  carpi  ulnaris,  of  which  the 
tendon  partially  overlaps  it  at  the  wrist.  The  artery  lies  for  a 
short  distance  on  the  brachialis  anticus ;  in  the  remainder  of  its 
course  it  lies  on  the  flexor  profundus  digitorum. 


TJLNAR    ARTERY.  293 

The  ulnar  nerve  is  at  first  separated  from  the  artery  by  a  con- 
siderable interval :  about  the  middle  of  the  forearm  it  joins  the 
artery,  and  accompanies  it  in  the  rest  of  its  course,  lying  close  to 
its  inner  side.  Both  pass  over  the  anterior  annular  ligament  of 
the  carpus,  lying  close  to  the  pisiform  bone, — the  nerve  being 
nearer  to  the  bone.  A  strong  expansion  from  the  tendon  of 
the  flexor  carpi  ulnaris  protects  them  in  this  exposed  situa- 
tion. 

Observe  that  the  ulnar  artery,  in  the  lower  third  of  its  course:, 
lies  under  the  radial  border  of  the  tendon  of  the  flexor  carpi 
ulnaris,  which  is  the  surgical  guide  to  the  vessel.  The  artery  is 
accompanied  by  two  veins,  which  join  the  venae  comites  of  the 
brachial. 

The  ulnar  artery  gives  off  the  following  branches  in  the  fore- 
arm : — 

a.  The  anterior  and  posterior  ulnar  recurrent  arteries  arise  immediately 
below  the  elbow-joint, — sometimes  by  a  common  trunk.     The  anterior 
passes  upwards  between  the  brachialis  anticus  and  the  pronator  teres, 
and   inosculates  with  the  inferior  profunda  and  anastomotica  magna. 
The  posterior  ascends  between  the  flexor  sublimis  and  the  flexor  pro- 
fundus  digitorum,  to  the  space  between  the  internal  condyle  and  the 
olecranon  :  it  then  passes  up  between  the  two  heads  of  the  flexor  carpi 
ulnaris,  where  it   inosculates  with    the  inferior  profunda,  the  anasto- 
motica magna,  and,  above  the  olecranon,  with  the  posterior  interosseous 
recurrent  (p.  280). 

b.  The  common  interosseous  artery  is  about  half  an  inch  long.  It  arises 
from  the  ulnar,  just  below  the  tubercle  of  the  radius,  and  soon  divides  into 
the  anterior  and   posterior  interosseous,  which  we  shall  examine  pre- 
sently. 

c.  The  carpal  branches  are  given  off  j  ust  above  the  pisiform  bone : 
the  posterior  carpal  runs  beneath    the   extensor  tendons,  and   forms, 
with  the  corresponding  branch    of  the  radial   artery,    an   arch,  from 
which  are  usually  given  off  the  second  and  third  dorsal  interosseous  ar- 
teries :  these  anastomose  with   the  perforating  arteries.     The  anterior 
carpal  runs  in  front  of  the  carpus,  supplies  the  synovial  membrane  and 
the  ligaments,  and  anastomoses  with  the  anterior  carpal  from  the  radial. 

d.  Muscular  branches  are  also  distributed  from  the  trunk  of  the  ulnar 
artery  in  its  course. 


294  MEDIAN    NERVE    IN    THE    FOREARM. 

This  nerve  runs    behind  the  internal  condvle, 
ULNAR  NERVE.  .    .          f  ,-,      a  .      ,        . 

between  the  two  origins  of  the  flexor  carpi  ulnaris. 

In  its  course  down  the  upper  part  of  the  forearm,  the  nerve  is  still 
covered  by  this  muscle,  and  lies  upon  the  flexor  profundus  digi- 
torum.  About  the  middle  of  the  forearm,  the  nerve  joins  the 
ulnar  artery,  and  runs  along  its  inner  side  over  the  anterior  annular 
ligament  into  the  palm. 

The  uluar  nerve,  as  it  lies  behind  the  elbow,  gives  off  some 
filaments  to  the  joint.  It  supplies  branches  to  the  flexor  carpi 
ulnaris,  and  to  the  ulnar  half  of  the  flexor  profundus  digitorum. 
It  also  gives  off  a  small  cutaneous  branch,  which  accompanies  the 
ulnar  artery  to  the  palm. 

About  two  inches  above  the  styloid  process  of  the  ulna,  the 
nerve  gives  off,  to  the  back  of  the  hand,  its  dorsal  cutaneous 
branch,  which  is  of  considerable  size.  This  crosses  under  the 
tendon  of  the  flexor  carpi  ulnaris,  and,  immediately  below  the 
styloid  process  of  the  ulna,  appears  on  the  back  of  the  hand,  where 
it  divides  into  branches  which  supply  the  back  of  the  little  ringer, 
and  half  the  ring  finger  ;  here  also  it  sends  a  branch  which  com- 
municates with  the  corresponding  branch  of  the  radial  nerve. 

This  nerve,  at  the  bend  of  the  elbow,  lies  on  the 

MEDIAN  NERVE.      .  . 

inner  side  ot  the  brachial  artery.  It  then  passes 
between  the  two  origins  of  the  pronator  teres,  and  descends  along 
the  middle  of  the  forearm,  between  the  flexor  sublimis  and  the 
flexor  profundus  digitorum.  At  the  lower  part  of  the  forearm,  it 
becomes  more  superficial,  lying  about  the  middle  of  the  wrist,  be- 
tween the  outer  tendon  of  the  flexor  sublimis,  and  the  inner  border 
of  the  tendon  of  the  flexor  carpi  radialis  :  it  then  enters  the  palm 
beneath  the  anterior  annular  ligament,  and  divides  into  five  branches 
for  the  supply  of  the  thumb,  both  sides  of  the  fore  and  middle 
fingers,  and  the  outer  side  of  the  ring  finger.* 

Immediately  below  the  elbow,  the  median  nerve  sends  branches 
to  the  pronator  teres  and  all  the  flexor  muscles  of  the  forearm, 

*  If  the  tendon  of  the  palmaris  longus  happen  to  be  broader  than  usual,  it  may 
partially  cover  the  median  nerve  near  the  wrist. ;  but  most  frequently  the  nerve  is  im- 
mediately beneath  the  fascia,  the  tendon  lying  to  its  ulnar  side. 


FLEXOR    PROFUNDUS    DIGITORUM.  295 

except  the  flexor  carpi  ulnaris  and  the  ulnar  half  of  the  flexor  pro- 
fundus,  which  are  supplied  by  the  ulnar  nerve.  The  anterior 
interosseous  nerve,  a  branch  of  the  median,  runs  with  the  anterior 
interosseous  artery,  close  to  the  interosseous  membrane,  between 
the  flexor  longus  pollicis  and  flexor  profundus  digitorum  :  it  supplies 
both  these  muscles  and  the  pronator  quadratus. 

Before  the  median  nerve  passes  beneath  the  annular  ligament, 
it  sends  off  its  cutaneous  palmar  branch,  which  passes  over  the 
ligament,  and  divides  into  small  filaments  to  supply  the  skin  of  the 
palm  and  ball  of  the  thumb,  communicating  with  the  cutaneous 
palmar  branches  of  the  ulnar,  the  external  cutaneous,  and  the  radial. 

Now  reflect  the  superficial  layer  of  muscles,  to 
DISSECTION.  ,,  i        i  j.   j       T>  .L-U 

see  those  more  deeply  seated.     .Preserve  the  prin- 
cipal vessels  and  nerves. 

The  deep-seated  muscles  are  the  flexor  digitorum  profundus, 
and  the  flexor  longus  pollicis ;  beneath  both,  near  the  wrist,  lies 
the  pronator  quadratus.  Close  to  the  interosseous  membrane  run 
the  anterior  interosseous  artery  and  nerve. 

FLEXOR  PRO-  This  *s  the  thickest  muscle  of  the  forearm.     It 

FTJNDUS  DIGITO-  arises  from  the  upper  two-thirds  of  the  anterior 
EUM-  surface  of  the  ulna,  from  the  same  extent  of  its 

internal  surface,  from  the  aponeurosis  attached  to  the  posterior 
edge  of  the  ulna,  and  from  the  inner  two-thirds  of  the  interosseous 
membrane.  About  the  middle  of  the  forearm  it  divides  into  four 
muscular  slips,  which  terminate  in  flat  tendons.  These  tendons 
lie  upon  the  same  plane,  and  pass  beneath  the  annular  ligament, 
under  those  of  the  superficial  flexor,  into  the  palm.  On  the  first 
phalanx  of  the  fingers,  the  tendons  of  the  deep  flexor  perforate 
those  of  the  superficial,  and  are  inserted  into  the  base  of  the  third 
or  ungual  phalanx.  It  derives  its  nerves  from  the  interosseous 
branch  of  the  median  and  the  ulnar. 

FLEXOB.  LONGUS         This  muscle  is  situated  on  the  front  surface  of 
POLLICIS.  the  radius,  outside  the  preceding.     It  arises  from 

the  front  surface  of  the  radius,  between  the  tubercle  and  the  pro- 
nator quadratus,  and  from  the  interosseous  membrane.*    Its  tendon 
*  Sometimes  by  a  slip  from  the  coronoid  process. 


296  AXTEBIOB   IXTEBOSSEOUS   ARTEBY. 

proceeds  beneath  the  annular  ligament  to  the  base  of  the  last 
phalanx  of  the  thumb.  Its  nerve  comes  from  the  interosseous 
branch  of  the  median. 

PROXATOR  This  square  muscle  arises  from  the  lower  fourth 

QVADRATTS.  of  the  ulna ;  its  fibres  pass  some  transversely,  some 

obliquely  outwards,  and  are  inserted  into  the  lower  fourth  of  the 
radius.  It  pronates  the  radius  on  the  ulna.  Its  nerve  proceeds 
from  the  interosseous  branch  of  the  median. 

ANTERIOR  CSTKR-  Nearly  on  a  level  with  the  insertion  of  the 
OSSBOCS  ARTERY.  biceps,  the  ulnar  artery  gives  off  from  its  outer 
side  the  common  interosse&us,  which  runs  backwards  for  about 
half  an  inch,  and  divides  into  the  anterior  and  posterior  inter- 
osseous. 

The  anterior  interosseous  artery  runs  close  to  the  interosseous 
membrane,  lying  between  the  flexor  profundus  digitorum  and 
flexor  longus  pollicis.  At  the  upper  edge  of  the  pronator  quadratus 
it  divides  into  two  branches ;  one  of  which,  the  smaller,  passes  be- 
hind the  muscle,  supplies  it  and  the  front  of  the  carpal  bones, 
communicating  with  the  anterior  carpal  arteries  from  the  radial 
and  ulnar;  the  other,  the  more  important,  perforates  the  inter- 
osseous membrane,  and  helps  to  supply  the  muscles  on  the  back  of 
the  forearm. 

A  branch,  the  arteria  comes  nervi  mediani,  proceeds  from  the  anterior 
interosseous.  It  lies  in  close  contact  with  the  nerve,  sometimes  in  its 
very  centre  :  though  usually  of  small  size,  it  may  be  as  large  as  the  ulnar 
artery  itself,  and,  in  such  cases,  it  passes  under  the  annular  ligament 
with  the  nerve  to  join  the  palmar  arch.  This  is  interesting,  because  it 
helps  to  explain  the  recurrence  of  haemorrhage  from  a  wound  in  the  palm 
even  after  the  radial  and  ulnar  arteries  have  been  tied. 

The  anterior  interosseous  artery  gives  off  branches  to  the  muscles  on 
either  side,  and  the  nutrient  arteries,  which  enter  the  radius  and  ulna, 
from  below  upwards,  near  the  centre  of  the  forearm,  to  supply  the 
medullary  membrane. 

ASTKRIOR  ra-  This  nerve  is  a  branch  of  the  median ;  it  gene- 

TEROSSBOCS  rally  runs  close  to  the  radial  side  of  the  artery, 

and  supplies  the  flexor  longus  pollicis,  half  the 
flexor  profundus  digitorum,  and  the  pronator  quadratus. 


PALM    OP    THE    HAND. 


DISSECTION  OF  THE  PALM  OF  THE  HAND. 

I)i  Make  a  vertical  incision  along  the  centre  of  the 

palm,  and  a  transverse  one  along  the  bases  of  the 
fingers ;  from  this  transverse  cut  continue  vertical  incisions  along 
the  front  of  the  fingers,  and  reflect  the  skin ;  taking  care  not  to 
remove  a  small  cutaneous  muscle — the  palmaris  brevis — situated 
near  the  ball  of  the  little  finger,  and  also  two  small  cutaneous 
branches  of  the  median  and  ulnar  nerves,  which  are  found  in  the 
fat  of  the  palm. 

Observe  how  closely,  in  the  centre  of  the  palm,  the  skin  adheres 
to  the  palmar  fascia  beneath  it.  On  the  ball  of  the  little  finger 
and  the  distal  ends  of  the  metacarpal  bones,  the  subcutaneous 
structure  is  composed  of  a  dense  filamentous  tissue,  which  con- 
tains numerous  pellets  of  fat,  forming  an  elastic  pad.  A  similar 
padding  protects  the  palmar  surfaces  of  the  fingers.  These  cushions 
on  the  ends  of  the  fingers  defend  them  in  the  powerful  actions 
of  the  hand ;  they  are  also  useful  in  subservience  to  the  nerves 
of  touch. 

The  palm  is  supplied  with  nerves  by  two  small  branches — one, 
the  palmar  branch  of  the  median,  passes  in  front  of  the  anterior 
annular  ligament  to  the  centre  of  the  palm ;  the  other,  the  palmar 
branch  of  the  ulnar,  supplies  the  inner  aspect  of  the  hand. 

PALMABIS  This  small  cutaneous  muscle  is  situated  on  the 

BEEVIS.  inner  side  of  the  palm.     It  arises  from  the  inner 

edge  of  the  central  palmar  fascia,  and  is  inserted  into  the  skin  on 
the  inner  side  of  the  palm.  Its  use  is  to  support  the  pad  on  the 
inner  edge  of  the  palm :  it  acts  powerfully  as  we  grasp ;  it  raises 
the  inner  edge  of  the  palm  and  deepens  the  hollow  of  it,  forming 
the  so-called  'cup  of  Diogenes.'  It  is  supplied  by  the  ulnar  nerve. 
This  fascia  has  a  silvery  lustre,  and,  in  the 

PALMAR  FASCIA.  .        J 

centre   of   the   palm,   is   remarkably   dense   and 

strong.  It  is  divided  into  three  portions,  a  central — by  far  the 
strongest ;  an  external,  covering  the  muscles  of  the  thumb ;  and 
an  internal,  covering  the  muscles  of  the  little  finger.  From  the 


298  PALM    OF    THE    HAND. 

deep  surface  of  the  fascia  two  septa  dip  down,  and  divide  the  palm 
into  three  separate  compartments ;  one  for  the  ball  of  the  thumb, 
a  second  for  that  of  the  little  finger,  and  a  third  for  the  centre  of 
the  palm. 

The  fascia  is  formed  by  a  prolongation  from  the  anterior 
annular  ligament.  It  is  also  strengthened  by  the  expanded  tendon 
of  the  palmaris  longus. 

The  central  portion  of  the  fascia  is  triangular,  with  the  apex 
at  the  wrist.  About  the  middle  of  the  palm  it  splits  into  four 
portions,  which  are  connected  by  transverse  tendinous  fibres, 
extending  completely  across  the  palm,  and  corresponding  pretty 
nearly  to  the  transverse  furrow  of  the  skin  in  this  situation. 

Examine  any  one  of  these  four  portions  of  the  fascia,  and  you 
will  find  that  it  splits  into  two  strips  which  embrace  the  corre- 
sponding flexor  tendons,  and  are  intimately  connected  with  the 
transverse  metacarpal  ligament.  The  effect  of  this  is  that  the 
flexor  tendons  of  each  finger  are  kept  in  place  in  the  palm,  by  a 
fibrous  ring.  Between  the  four  divisions  of  the  palmar  fascia  the 
digital  vessels  and  nerves  emerge,  and  descend  in  a  line  with  the 
clefts  between  the  fingers. 

In  the  hands  of  mechanics,  in  whom  the  palmar  fascia  is  usually 
very  strong,  we  find  that  slips  of  it  are  lost  in  the  skin  at  the 
lower  part  of  the  palm,  and  also  for  a  short  distance  along  the 
sides  of  the  fingers. 

The  chief  use  of  the  palmar  fascia  is,  to  protect  the  vessels  and 
nerves  from  pressure,  when  anything  is  grasped  in  the  hand.  It 
also  confines  the  flexor  tendons  in  their  proper  place. 

B.eneath  the  interdigital  folds  of  the  skin,  there  are  apo- 
neurotic  fibres  to  strengthen  them,  constituting  what  are  called  the 
transverse  ligaments  of  the  fingers.  They  form  a  continuous  liga- 
ment across  the  lower  part  of  the  palm,  in  front  of  the  digital 
vessels  and  nerves. 

Cut  through  the  palmar  fascia  at  its  attachment 

to  the  anterior  annular  ligament,  and  reflect  it 

towards  the  fingers,  so  as  to  expose  the  vessels,  nerves,  and  tendons 

in  the  palm.     The  vessels  lie  above  the  nerves,  and  the  tendons 


PALM    OF    THE    HAND. 


299 


still  deeper.  There  is  an  abundance  of  loose  connective  tissue  to 
allow  the  free  play  of  the  tendons.  When  suppuration  takes  place 
in  the  palm,  it  is  seated  in  this  tissue.  Eeflect  for  a  moment 
what  mischief  is  likely  to  ensue.  The  pus  cannot  come  to  the 

FIG.  58. 


Radial  artery    . 


Supcrficialis  vote 


Arteria  magna 
pollicis  .    . 


Radialis  indicia . 


Ulnar  artery. 


Ulnaris  profumla. 


DIAGRAM    OF   THE    SUPERFICIAL    AND    DEEP    PALMAR    ARCHES. 

1,  2,' 3,  4.  Interosseous  branches. 

surface  through  the  dense  palmar  fascia,  or  on  the  back  of  the 
hand  ;  it  will  therefore  run  up  into  the  carpal  bursa  under  the 
annular  ligament,  and  make  its  way  deep  amongst  the  tendons  of 
the  forearm. 


300  PALM    OP    THE    HAND. 

SUPERFICIAL  The  ulnar  artery,  having  passed  over  the  annular 

PALMAR  AHCH.  ligament,  near  the  pisiform  bone,  describes  a 
curve  across  the  upper  part  of  the  palm,  beneath  the  palmar  fascia, 
towards  the  thumb,  and,  gradually  diminishing  in  size,  inosculates 
with  the  superficialis  volse,  and  very  commonly  with  a  branch  from 
the  arteria  radialis  indicis,  to  form  the  superficial  palmar  arch. 
The  curve  of  the  arch  is  directed  towards  the  fingers,  its  greatest 
convexity  descending  as  low  as  a  horizontal  line  drawn  across  the 
junction  of  the  upper  with  the  middle  third  of  the  palm. 

In  its  passage  over  the  annular  ligament,  the  artery  lies  in  the 
furrow,  between  the  pisiform  and  unciform  bones,  and  is  protected 
by  an  expansion  from  the  tendon  of  the  flexor  carpi  ulnaris  to  the 
palmaris  longus.  The  ulnar  nerve  lies  close  to  the  inner  side  of 
the  artery,  both  being  covered  by  the  palmaris  brevis.  In  the 
palm,  the  artery  rests  for  a  short  distance  upon  the  muscles  of 
the  little  finger,  then  it  lies  upon  the  superficial  flexor  tendons 
and  the  divisions  of  the  ulnar  and  median  nerves ;  and  is  covered 
by  the  palmar  fascia. 

BRANCHES  OF  Immediately  below  the  pisiform  bone,  the  ulnar 

THE  ULNAE  AB-  artery  gives  off  the  ulnaris  profunda,  which  sinks 
TEHY  IN  THE  deeply  into  the  palm,  between  the  abductor  and  flexor 

ALM'  brevis  minimi  digiti,  to  form  the  deep  palmar  arch,  by 

joining  the  terminal  branch  of  the  radial  artery.  It  is  accompanied  by 
the  deep  branch  of  the  ulnar  nerve. 

From  the  concavity  of  the  arch  small  recurrent  branches  ascend  to 
the  carpus,  and  inosculate  with  the  other  carpal  branches  of  the  radial 
and  ulnar  arteries. 

Four  digital  arteries  arise  from  the  convexity  of  the  arch.  They 
supply  all  the  fingers,  except  the  radial  side  of  the  index  finger.  The 
first  descends  over  the  muscles  on  the  inner  side  of  the  palm,  to  the  ulnar 
side  of  the  little  finger,  along  which  it  runs  to  the  apex.  The  second, 
third,  and  fourth  descend  nearly  vertically  between  the  tendons,  in  a  line 
with  the  clefts  between  the  fingers,  and,  about  half  an  inch  above  the  clefts, 
each  divides  into  two  branches,  which  proceed  along  the  opposite  sides  of 
the  fingers  nearly  to  the  end  of  the  last  phalanges,  where  they  unite  to 
form  an  arch  with  the  convexity  towards  the  end  of  the  finger ;  from 
this  arch  numerous  branches  supply  the  papillae  at  the  tip  of  the  finger. 


PALM    OF    THE    HAND.  801 

In  the  palm  of  the  hand  the  digital  arteries,  before  they  divide, 
are  joined  by  branches  from  the  corresponding  palmar  interosseous 
arteries  (branches  of  the  deep  palmar  arch)  (fig.  58). 

The  digital  arteries  freely  communicate,  on  the  palmar  and 
dorsal  aspect  of  the  fingers,  by  transverse  branches,  which  supply 
the  joints  and  the  sheaths  of  the  tendons.  Near  the  ungual 
phalanx,  a  considerable  branch  passes  to  the  back  of  the  finger, 
and  forms,  a  network  of  vessels  which  supply  the  matrix  of  the 
nail. 

ULNAR  NERYE  The  ulnar  nerve  passes  over  the  annular  liga- 
IN  THE  PALM.  ment  into  the  palm,  on  the  inner  side  of  the 

ulnar  artery,  and  a  little  behind  it.  It  lies  in  the  groove  between 
the  pisiform  and  unciform  bones,  so  that  it  is  perfectly  secure  from 
pressure.  Immediately  below  the  pisiform  bone,  the  nerve  divides 
into  a  superficial  and  a  deep  palmar  branch.  The  deep  branch 
supplies  the  muscles  forming  the  ball  of  the  little  finger,  and 
accompanies  the  ulnaris  profunda  artery  into  the  palm,  to  supply 
all  the  interosseous  muscles,  the  two  inner  lumbricales,  the  adductor 
pollicis,  and  the  inner  head  of  the  flexor  brevis  pollicis.  The  super- 
ficial branch  sends  filaments  to  the  palmaris  brevis,  to  the  skin  on 
the  inner  side  of  the  palm,  and  then  divides  into  two  digital  nerves, 
one  for  the  supply  of  the  ulnar  side  of  the  little  finger,  the  other 
for  the  contiguous  sides  of  the  little  and  ring  fingers.  This  branch 
also  communicates  with  the  median  nerve  behind  the  superficial 
palmar  arch.  All  the  digital  branches  run  along  the  sides  of  the 
fingers  to  their  extremities  superficial  to  their  corresponding 
arteries. 

ANTERIOR  AN-  This  exceedingly  strong  and  thick  ligament  con- 
HULAR  LIGAMENT  fines  the  flexor  tendons  of  the  fingers  and  thumb, 
OF  THE  CARPUS.  an(j  fastens  together  the  bones  of  the  carpus.  It 
is  attached,  externally,  to  the  scaphoid  and  trapezium ;  inter- 
nally, to  the  pisiform  and  unciform.  Its  upper  border  is  con- 
tinuous with  the  aponeurosis  in  front  of  the  wrist ;  its  lower  is 
connected  with  the  palmar  fascia ;  its  anterior  surface  receives  the 
expanded  tendon  of  the  palmaris  longus,  and  gives  origin  to  most 
of  the  muscles  of  the  ball  of  the  thumb  and  little  finger. 


302  PALM    OP    THE    HAND. 

Cut  vertically  through  the  ligament,  and  ob- 

DlSSECTION.  .  '        - 

serve  that,  with  the  carpal  bones,  it  forms  an 
elliptical  canal,  with  the  broad  diameter  transversely.  This  canal 
is  lined  by  a  synovial  membrane  which  is  reflected  loosely  over  the 
tendons.  Superficial  to  the  ligament,  pass  the  palmaris  longus, 
the  ulnar  artery  and  nerve,  and  the  palmar  branch  of  the  median 
nerve ;  beneath  it,  pass  the  superficial  and  deep  flexor  tendons  of 
the  fingers,  the  long  flexor  tendon  of  the  thumb,  and  the  median 
nerve.  The  tendon  of  the  flexor  carpi  radialis  does  not  run  with 
the  other  tendons,  but  is  contained  in  a  distinct  sheath,  lined  by  a 
separate  synovial  membrane,  formed,  partly  by  the  annular  liga- 
ment, and,  partly,  by  the  groove  in  the  trapezium. 

MEDIAN  NERVE         In  its  passage  under  the  annular  ligament,  the 
IN  THE  PALM.  median  nerve  is  enveloped  in  a  fold  of  synovial 

membrane,  and  lies  upon  the  flexor  tendons.  Here  it  divides 
into  two  nearly  equal  parts ;  the  external  gives  branches  to  the 
muscles  of  the  ball  of  the  thumb,  namely,  to  the  abductor  pollicis, 
the  opponens  pollicis,  and  the  outer  head  of  the  flexor  brevis 
pollicis,  and  then  terminates  in  three  digital  nerves,  two  of  which 
are  distributed  to  the  thumb,  and  the  third  to  the  outer  side  of 
the  index  finger ;  the  internal  gives  digital  branches  which  supply 
the  inner  side  of  the  forefinger,  both  sides  of  the  middle  finger, 
and  the  radial  side  of  the  ring  finger. 

The  two  nerves  to  the  thumb  proceed,  one  on  each  side  of  the  long 
flexor  tendon,  to  the  last  phalanx  :  the  outer  one  being  connected  with  a 
terminal  filament  of  the  radial. 

.  The  third  digital  nerve  runs  along  the  radial  side  of  the  index  finger. 
The  fourth  descends  towards  the  cleft  between  the  index  and  middle 
fingers,  and  subdivides  into  two  branches,  which  supply  their  opposite 
sides.  The  fifth  is  joined  by  a  filament  from  one  of  the  ulnar  digital 
nerves,  and  then  subdivides  above  the  cleft  between  the  middle  and  ring 
fingers,  to  supply  their  opposite  sides. 

Two  small  branches  are  given  off  from  the  third  and  fourth  digital 
nerves,  to  supply  the  two  outer  lurabricales ;  the  two  inner  being  supplied 
by  the  ulnar. 

About  an  inch  and  a  quarter  above  the  clefts  between  the  fingers, 
each  digital  nerve  subdivides  into  two  branches,  between  which  the 


PALM    OF    THE    HAND.  303 

digital  artery  passes  and  bifurcates  lower  down ;  therefore  a  vertical  in- 
cision down  the  cleft  would  divide  the  artery  before  -the  nerve. 

In  their  course  along  the  fingers  and  thumb,  the  nerves  lie 
superficial  to  the  arteries,  and  nearer  to  the  flexor  tendons.  About 
the  middle  of  the  first  phalanx  each  nerve  sends  a  branch,  which 
runs  along  the  back  of  .the  finger  nearly  to  the  extremity,  commu- 
nicating with  the  dorsal  branches,  derived  from  the  radial  and 
ulnar  nerves.*  Near  the  ungual  phalanx  another  branch  is  dis- 
tributed to  the  skin  around  and  beneath  the  matrix  of  the  nail. 
Each  digital  nerve  terminates  in  the  cushion  at  the  end  of  the 
finger  in  a  brush  of  filaments,  with  their  points  directed  into  the 
papillae  of  the  skin. 

FLEXOH   TEN-  Immediately  below  the   annular  ligament  the 

DONS  AND  THEIB  tendons  separate  from  each  other :  near  the  meta- 
SHEATHS.  carpal  joints  they  pass  in  pairs,  through  strong 

fibrous  rings  (p.  298)  formed  by  the  divisions  of  the  palmar  fascia. 
Below  the  metacarpal  joint  the  two  tendons  for  each  finger  enter 
the  sheath,  theca,  which  confines  them  in  their  course  along  the 
phalanges.  It  is  formed  by  a  strong  fibrous  membrane,  which  is 
attached  to  the  ridges  on  the  phalanges,  and  converts  the  groove 
in  front  of  these  bones  into  a  complete  canal,  exactly  large  enough 
to  contain  the  tendons.  The  density  of  the  sheath  varies  in  par- 
ticular situations,  otherwise  there  would  be  an  obstacle  to  the  easy 
flexion  of  the  fingers.  To  ascertain  this,  cut  open  one  of  the 
sheaths  along  its  entire  length  ;  you  will  then  see  that  it  is  much 

*  UpoD  the  cutaneous  nerves  of  the  hand  and  feet  are  little  bodies,  termed,  after 
their  discoverer,  corpuscles  of  Pacini.  Some  of  them  will  be  found,  by  carefully 
examining  the  trunk  of  a  nerve,  or  one  of  its  smaller  branches,  in  the  subcutaneous 
tissue  at  the  root  of  a  finger.  Each  corpuscle  is  about  fa  of  an  inch  long,  and  is 
attached  by  a  slender  fibro-cellular  pedicle  to  the  nerve  upon  which  it  is  situated; 
through  the  pedicle,  a  single  primitive  nerve  fibril  passes  into  the  corpuscle.  The 
corpuscle  itself  is  composed  of  a  series  of  concentric  capsules,  varying  from  twenty  to 
fifty  in  number,  and  separated  by  intervals  containing  fluid :  and  the  nerve  fibril 
terminates  by  a  dilated  extremity  in  a  central  cavity,  which  exists  in  the  axis  of  the 
corpuscle.  Their  function  is  unknown.  These  bodies  are  found  in  many  other  situa- 
tions, viz.,  in  the  solar  plexus,  the  pudic  nerves,  the  intercostal  nerves,  the  cutaneous 
nerves  of  the  arm  and  neck,  the  infra-orbital  nerve,  the  sacral  plexus,  and  in  nerves 
supplying  the  periosteum.  They  can  be  best  examined  in  the  mesentery  of  the  cat. 


304  PALM    OP   THE    HAND. 

stronger  between  the  joints  than  over  the  joints  themselves. 
Through  these  sheaths,  inflammation  commencing  in  the  integu- 
ments of  the  ringer  may  readily  extend  to  the  synovial  membrane 
of  the  tendon. 

In  cases  of  whitlow,  when  pus  forms  in  the  theca,  the  incision 
should  be  made  deep  enough  to  lay  open  this  fibro-osseous  canal, 
without  which  the  incision  will  be  of  no  use.  It  is  obvious  that 
the  incision  should  be  made  down  the  centre  of  the  finger,  to  avoid 
the  digital  nerves  and  arteries.  If  this  opening  be  not  timely 
made,  the  flexor  tendons  are  likely  to  slough,  and  the  finger  be- 
comes stiff.* 

But  what  protects  the  joints  of  the  fingers  where  the  flexor 
tendons  play  over  them  ?  Look  into  an  open  sheath,  and  you  will 
see  that  in  front  of  the  joints  the  tendons  glide  over  a  smooth  fibro- 
cartilaginous  structure,  called  the  '-palmar '  ligament. 

To  facilitate  the  play  of  the  tendons,  the  interior  of  the  sheath, 
as  well  as  the  tendons, 'is  lined  by  a  synovial  membrane,  of  the 
extent  of  which  it  is  important  to  have  a  correct  knowledge.  With 
a  probe  you  may  ascertain  that  the  synovial  membrane  is  reflected 
from  the  sheath  upon  the  tendons,  a  little  above  the  metacarpal 
joints  of  the  fingers ;  that  is,  nearly  in  a  line  with  the  transverse 
fold  in  the  skin  in  the  lower  third  of  the  palm.  Towards  the  distal 
end  of  the  finger,  the  synovial  sheath  stops  short  of  the  last  joint, 
so  that  it  is  not  injured  in  amputation  of  the  ungual  phalanx. 

And  now  notice  how  the  tendons  are  adapted  to  each  other  in 
their  course  along  the  finger.  The  superficial  flexor,  near  the  root 
of  the  finger,  becomes  slightly  grooved  to  receive  the  deep  flexor  ; 
about  the  middle  of  the  first  phalanx  it  splits  into  two  portions, 
through  which  the  deep  flexor  passes.  The  two  portions  reunite 

*  On  closer  inspection  it  will  be  observed  that  the  sheath  is  composed  of  bands 
of  fibres,  -which  take  different  directions,  and  have  received  distinct  names.  The 
strongest  are  called  the  '  ligamenta  vaginalia.'  They  constitute  the  sheath  over  the 
body  of  the  phalanx,  and  extend  transversely  from  one  side  of  the  bone  to  the  other. 
The  '  ligamenta  cruciata '  are  two  slips,  which  cross  obliquely  over  the  tendons.  The 
'  ligamenta  annularia '  are  situated  immediately  in  front  of  the  joints,  and  may  be 
considered  as  thin  continuations  of  the  ligamenta  vaginalia.  They  consist  of  fibres, 
which  are  attached  on  either  side  to  the  lateral  ligaments  of  the  joints,  and  pass 
transversely  over  the  tendons. 


PALM    OP    THE    HAND.  305 

below  the  deep  tendon  so  as  to  embrace  it,  and  then  divide  a 
second  time  into  two  slips,  which  interlace  with  each  other  and  are 
inserted  into  the  sides  of  the  second  phalanx.  The  deep  flexor, 
having  passed  through  the  opening  of  the  superficial  one,  is  inserted 
into  the  base  of  the  last  phalanx.* 

In  what  way  are  the  tendons  supplied  with  blood  ?  Kaise  and 
separate  the  tendons,  and  you  will  see  that  slender  but  very  vas- 
cular folds  of  synovial  membrane  (vincula  teudinum)  run  up  from 
the  phalanges  and  convey  blood-vessels  to  the  tendons. 

The  tendon  of  the  flexor  longuspollicis  lies  on  the  radial  side  of 
the  other  tendons  beneath  the  annular  ligament.  It  passes  between 
the  two  portions  of  the  flexor  brevis  pollicis  and  the  two  sesamoid  bones 
of  the  thumb,  enters  its  proper  sheath,  and  is  inserted  into  the  base 
of  the  last  phalanx.  Its  synovial  sheath  is  prolonged  from  the  large 
bursaof  the  flexor  ten  dons  beneath  the  annular  ligament,  and  accom- 
panies the  tendon  down  to  the  last  joint  of  the  thumb ;  conse- 
quently the  sheath  is  injured  in  amputation  of  the  last  phalanx. 

BUBSAL  SAC  OF          A  large  and  loose  synovial  sac  (bursa  of  the  car- 
THE  CABPUS.  pns)  facilitates  the  play  of  the  tendons  beneath 

the  anterior  annular  ligament.  It  lines  the  under  surface  of  the 
ligament  and  the  groove  of  the  carpus,  and  is  reflected  in  loose 
folds  over  the  tendons.  It  is  prolonged  up  the  tendons  for  an  inch 
and  a  half,  or  two  inches,  and  forms  a  cul-de-sac  above  the  ligament. 
Below  the  ligament  the  bursa  extends  into  the  palm,  and  sends  off 
prolongations  for  each  of  the  flexor  tendons,  which  accompany  them 
down  to  the  middle  of  the  hand.  You  will  understand  that,  when 
the  bursa  is  inflamed  and  distended  by  fluid,  there  will  be  a  bulg- 
ing above  the  annular  ligament,  and  another  in  the  palm,  with 
perceptible  fluctuation  between  them ;  the  unyielding  ligament 
causing  a  constriction  in  the  centre,  f 

*  In  the  Museum  of  the  College  of  Surgeons,  a  preparation  is  put  up  which  shows 
a  beautiful  piece  of  animal  mechanics  concerning  the  flexor  tendons ;  namely,  that  in 
its  passage  along  the  phalanges,  the  deep  flexor  forms,  at  the  first  phalanx,  a  kind  of 
little  patella  for  the  superficial  one  ;  but,  at  the  second  phalanx,  the  superficial  flexor 
lies  deeper  than  the  other,  and  forms  a  little  patella  for  it.  This  increases  the  leverage 
in  each  case. 

f  In  only  one  subject  have  we  seen  an  instance  in  which  this  bursa  communicated 

X 


306  PALM    OF    THE    HAND. 

These  four  slender  muscles,  one  for  each  finger, 
are  attached  to  the  deep  flexor  tendons  in  the  palm. 
All  of  them  arise  from  the  radial  side  of  the  deep  tendon  of  their 
corresponding  finger  :  the  third  and  fourth  also  arise  from  the 
adjacent  sides  of  two  tendons.  Each  terminates  in  a  broad  thin 
tendon  which  passes  over  the  radial  side  of  the  first  joint  of  the 
finger,  and  is  inserted  into  the  extensor  tendon  on  the  dorsal  aspect 
of  the  first  phalanx  of  the  finger.  Their  action  is  to  bend  the  first 
joint  of  the  fingers.  Being  inserted  near  the  centre  of  motion, 
they  can  move  the  fingers  with  great  rapidity.  As  they  produce 
the  quick  motions  of  the  musician's  fingers,  they  were  called  by 
the  old  anatomists  '  fidicinales.' 

The  two  inner  lumbricales  are  supplied  by  the  deep  branch  of 
the  ulnar  nerve;  the  two  outer  by  the  third  and  fourth  digital 
branches  of  the  median. 

Now  proceed  to  the  muscles  composing  the  ball  of  the  thumb 
and  the  little  finger.  The  dissection  of  them  requires  consider- 
able care. 

MUSCLES  OF  The  great  strength  of  the  muscles  of  the  ball 

THE  BALL  OF  of  the  thumb  (unde  nomen  pollicis),  is  one  of  the 

THE  THUMB.  distinguishing  features  of  the  human  hand.     This 

strength  is  necessary  in  order  to  oppose  that  of  all  the  fingers.  In 
addition  to  its  strength,  the  thumb  enjoys  perfect  mobility.  It 
has  no  less  than  eight  muscles — namely,  an  abductor,  an  opponens, 
two  flexors,  three  extensors,  and  an  adductor. 

ABDUCTOR  This  is  the  most  superficial.     It  is  a  thin,  flat 

POLLICIS.  muscle,  and  arises  from  the  ridge  of  the  os  tra- 

pezium and  the  annular  ligament.  It  is  inserted  by  a  flat  tendon 
into  the  base  of  the  first  phalanx  of  the  thumb.  Its  action  is  to 
draw  the  thumb  away  from  the  fingers.  Its  nerve  comes  from 
the  median.  Keflect  it  from  its  insertion  to  expose  the  follow- 
ing :— 

with  the  wrist  joint.  It  communicates  always  with  the  synovial  sheath  of  the  long 
flexor  of  the  thumb,  in  most  cases  with  that  of  the  flexors  of  the  little  finger,  and  but 
rarely  with  that  of  the  index,  middle,  and  ring  fingers.  For  this  reason,  inflammation 
of  the  theca  of  the  thumb  or  little  finger  is  more  liable  to  be  attended  with  serious 
consequences  than  either  of  the  others. 


PALM    OP    THE    HAND.  307 

OPPONENS  POL-         This  muscle  arises  from  the  os  trapezium  be- 
LICIS-  neath  the  abductor,  and  from  the  annular  ligament, 

and  is  inserted  into  the  whole  length  of  the  radial  side  of  the  meta- 
carpal  bone  of  the  thumb.  The  action  of  this  powerful  muscle 
is  to  oppose  the  thumb  to  all  the  fingers.  Its  nerve  comes  from 
the  median.  Reflect  it  from  its  insertion,  to  expose  the  follow- 
ing :— 

FLEXOR  BREVIS         This  muscle  has  two  origins ;  one,  the  super- 
POLLICIS.  ficial,  from  the  annular  ligament  and  os  trapezium  ; 

the  other,  the  deep,  from  the  os  trapezoides,  os  magnum,  and  the 
bases  of  the  second  and  third  metacarpal  bones.  It  is  inserted  by 
two  strong  tendons  into  the  base  of  the  first  phalanx  of  the 
thumb ;  the  superficial  tendon  being  connected  with  the  abductor 
pollicis,  and  the  deep  one,  with  the  adductor  pollicis.  A  sesamoid 
bone  is  found  in  each  of  the  tendons.  The  tendons  of  insertion  of 
this  muscle  are  separated  by  the  long  flexor  tendon  of  the  thumb 
and  the  arteria  magna  pollicis.  Its  action  is  to  bend  the  first 
phalanx  of  the  thumb.  The  superficial  portion  is  supplied  by  the 
median  nerve  ;  the  deep,  by  the  ulnar. 

ADDTJCTOB  POL-         This  muscle  arises  from  the  palmar  aspect  of 
LICIS.  the  shaft  of  the  metacarpal  bone  of  the  middle 

finger ;  its  fibres  converge  and  are  inserted,  along  with  the  deep 
or  inner  portion  of  the  flexor  brevis  pollicis,  into  the  base  of  the 
first  phalanx  of  the  thumb.  Its  action  is  to  draw  the  thumb 
towards  the  palm,  as  when  we  bring  the  tips  of  the  thumb  and 
little  finger  into  contact.  It  is  supplied  by  the  deep  branch  of 
the  ulnar  nerve,  which  also  supplies  the  inner  head  of  the  flexor 
brevis  pollicis.  The  other  muscles  of  the  ball  of  the  thumb  are 
supplied  by  the  median  nerve. 

MUSCLES  OF  THE         The  muscles  of  the  little  finger  correspond  in 
BALL  OF  THE  some  measure  with  those  of  the  thumb.      Thus 

LITTLE  FINGEB.  there  is  an  abductor,  a  flexor  brevis,  and  an  op- 
ponens  minimi  digiti.  All  derive  their  nerves  from  the  deep 
branch  of  the  ulnar. 

ABDUCTOB  This,  the  most  superficial  of  the  muscles  of  the 

MINIMI  DIGITI.         little  finger,  arises  from  the  pisiform  bone,  and 

x  2 


308  PALM    OP   THE    HAND. 

from  the  tendinous  expansion  of  the  flexor  carpi  ulnaris :  it  is 
inserted  by  a  flat  tendon  into  the  inner  side  of  the  base  of  the  first 
phalanx  of  the  little  finger.  Its  action  is  to  draw  this  finger 
from  the  others.  Its  nerve  comes  from  the  deep  branch  of  the 
ulnar. 

FLEXOR  BREVIS  This  slender  muscle  may  be  considered  as  a 
MINIMI  DIGITI.  portion  of  the  preceding.  It  arises  from  the 
unciform  bone  and  annular  ligament,  and  is  inserted  with  the 
tendon  of  the  abductor  into  the  base  of  the  first  phalanx  of  the 
little  finger.  Its  action  is  similar  to  that  of  the  abductor.  Nerve 
from  deep  branch  of  ulnar.  Between  the  origins  of  the  abductor 
and  flexor  brevis  minimi  digiti,  the  deep  branch  of  the  ulnar  artery 
and  nerve  sinks  down  to  form  the  deep  palmar  arch. 

OPPONBNS  The  last  two  muscles  must  be  reflected  from 

MINIMI  DIGITI.  their  insertion,  to  expose  the  opponens  minimi 
digiti.  It  arises  from  the  unciform  process  and  the  annular 
ligament,  and  is  inserted  along  the  ulnar  side  of  the  shaft  of  the 
metacarpal  bone  of  the  little  finger.  Its  action  is  to  draw  this 
bone,  the  most  movable  of  all  the  metaearpal  bones  of  the  fingers, 
towards  the  thumb.  Thus  it  greatly  strengthens  the  grasp  of  the 
palm.  Nerve  from  deep  branch  of  ulnar. 

Now    cut  through  all  the  flexor  tendons,  and 
DISSECTION.  . 

remove  the  deep  fascia  of  the  palm,  to  see  the 

deep  arch  of  arteries  and  its  branches. 

B  ,  The  radial  artery,  sinking  into  the  space  be- 

THE  RADIAL  AR-  tween  the  first  and  second  metacarpal  bones,  enters 
TERT  IN  THE  the  palm  between  the  inner  head  of  the  flexor 

PALM-  brevis   and  the  adductor   pollicis,  and   gives   off 

three  branches — the  arteria  princeps  pollicis,  the  radialis  indicis, 
and  the  palmaris  profunda,  which  unites  with  the  ulnar  to  form 
the  deep  arch. 

The  arteria  princeps  pollicis  runs  in  front  of  the  abductor  indicis 
(first  dorsal  interosseous),  close  along  the  metacarpal  bone  of  the  thumb  : 
in  the  interval  between  the  lower  portions  of  the  flexor  brevis  pollicis, 
the  artery  divides  into  two  digital  branches,  which  proceed  one  on  either 
side  of  the  thumb,  and  inosculate  at  the  apex  of  the  last  phalanx.  Their 


PALM    OF    THE    HAND.  309 

distribution  and  mode  of  termination  are  like  those  of  the  other  digital 
arteries. 

The  arteria  radialis  indicis  runs  between  the  abductor  indicis  and 
adductor  pollicis,  along  the  radial  side  of  the  index  finger  to  the  end, 
where  it  forms  an  arch  with  the  other  digital  artery,  a  branch  of  the 
ulnar.  Near  the  lower  margin  of  the  adductor  pollicis,  the  radialis 
indicis  generally  receives  a  branch  from  the  superficial  palmar  arch. 

The palmaris  profunda  may  be  considered  as  the  continuation 
of  the  radial  artery.  It  enters  the  palm  between  the  inner  head  of 
the  flexor  brevis  and  the  adductor  pollicis,  and,  running  upon  the 
bases  of  the  metacarpal  bones,  inosculates  with  the  deep  branch  of 
the  ulnar  artery,  thus  completing  the  deep  palmar  arch.  From 
the  curve  of  the  arch  small  recurrent  branches  ascend  to  supply 
the  bones  and  joints  of  the  carpus,  inosculating  with  the  other 
carpal  arteries. 

From  the  convexity  of  the  arch  three  or  four  small  branches,  called 
palmar  interosseous  (fig.  58.  p.  299),  descend  to  supply  the  interosseous 
muscles,  and  near  the  clefts  of  the  fingers  communicate  with  the  digital 
arteries.  These  palmar  interosseous  branches  are  sometimes  of  consider- 
able size,  and  take  the  place  of  one  or  more  of  the  digital  arteries,  ordi- 
narily derived  from  the  superficial  palmar  arch.  Three  branches,  called 
perforating,  pass  between  the  upper  ends  of  the  metacarpal  bones  to  the 
back  of  the  hand,  and  communicate  with  the  carpal  branches  of  the  radial 
and  ulnar. 

DEEP  BBANCH  This  nerve  sinks  into  the  palm  with  the  ulnaris 

OF  THE  ULNAR  profunda  artery,  between  the  abductor  and  flexor 
NKRVE.  brevis  minimi  digiti.  It  then  runs  with  the  deep 

palmar  arch  towards  the  radial  side  of  the  palm,  and  terminates 
in  the  adductor  pollicis,  and  the  inner  or  deep  head  of  the  flexor 
brevis  pollicis.  Between  the  pisiform  and  unciform  bones,  the 
nerve  gives  a  branch  to  each  of  the  muscles  of  the  little  finger. 
Subsequently  it  sends  branches  to  each  interosseous  muscle,  and  to 
the  two  inner  lumbricales. 

The  tendon  of  the  flexor  carpi  radialis  in  the  palm  must  now 
be  followed  to  its  insertion  into  the  base  of  the  second  metacarpal 
bone. 


310  SUPERFICIAL   MUSCLES    OP    THE    BACK. 

The  dissection  of  the  remaining  muscles  of  the  palm,  called, 
from  their  position,  interossei,  must  be,  for  the  present,  post- 
poned. 


MUSCLES   OF  THE  BACK  CONNECTED    WITH   THE   ARM. 

Make  an  incision  down  the  spine  from  the 
occiput  to  the  sacrum  ;  another,  from  the  last 
dorsal  vertebra  upwards  and  outwards  to  the  acromion  ;  and  a 
third,  from  the  sacrum  along  the  crest  of  the  ilium  ;  then  reflect 
the  skin  outwards  from  the  dense  subcutaneous  tissue,  in  which 
will  be  found  the  following  cutaneous  nerves. 

CUTANKOUS  These  are  derived  from  the  posterior  divisions 

NEBVES  OF  THE  of  the  spinal  nerves,  and  correspond,  generally, 
to  the  number  of  the  vertebrae.  The  posterior 
primary  branches,  much  smaller  than  the  anterior,  divide,  between 
the  transverse  processes,  into  external  and  internal  branches. 
From  the  internal,  which  become  superficial  near  the  spines  of 
the  vertebra,  are  derived  those  branches  which  supply  the  skin  in 
the  cervical  and  upper  dorsal  regions  ;  from  the  external,  which 
appear  near  the  angles  of  the  ribs,  are  derived  those  which  supply 
the  skin  of  the  lower  dorsal  and  lumbar  regions.  In  the  cervical 
and  upper  dorsal  region,  the  cutaneous  nerves  perforate  the  com- 
plexus,  splenius,  and  trapezius ;  in  the  lower  dorsal  and  lumbar 
region,  they  perforate  the  serratus  posticus  inferior  and  latissimus 
dorsi.  As  might  be  expected,  the  external  branches  are  the  larger, 
especially  in  the  loins,  where  some  of  them  descend  over  the  crest 
of  the  ilium,  and  terminate  in  the  skin  of  the  buttock. 

Among  these  cutaneous  nerves,  notice,  at  this  stage  of  the  dis- 
section, the  following : — 

1.  The  posterior  branch  of  the  second  cervical  nerve  is  called 
the  great  occipital.     It  perforates  the  complexus,  and  ramifies  on 
the  back  of  the  scalp  with  the  occipital  artery. 

2.  The  posterior  branch  of  the  third  cervical  nerve  sometimes 
sends  a  branch  to  the  back  of  the  scalp. 


SUPERFICIAL    MUSCLES    OF    THE    BACK.  311 

3.  The  posterior  branch  of  the  second  dorsal  nerve  is  the  largest 
of  all  the  dorsal  cutaneous  nerves.     It  runs  outwards  and  ramifies 
in  the  skin  over  the  spine  of  the  scapula. 

4.  The   posterior  branch  of  the  second  lumbar  nerve  comes 
through  the  fascia  lumborum  near  the  posterior  superior  spine  of 
the  ilium,  and  runs  over  the  crest  of  that  bone  to  supply  the  skin 
of  the  buttock. 

^  The  trapezius  and  latissimus  dorsi,  which  form 

DISSECTION.  r 

the  first  layer  of  muscles,  must  now  be  cleaned  by 

dissecting  in  the  course  of  their  fibres. 

Alone,  this  muscle  is  triangular ;  with  its  fellow, 
it  presents  a  trapezoid  form.  It  arises  from  the 
inner  fourth,  more  or  less,  of  the  superior  curved  line  of  the  occi- 
put ;  from  the  ligamentum  nuchae,*  from  the  spines  of  the  seventh 
cervical,  and  all  the  dorsal  vertebrae,  and  from  their  supra-spinous 
ligaments.  The  fibres  converge  towards  the  shoulder.  The  upper 
are  inserted  fleshy  into  the  external  third  of  the  clavicle;  the 
middle,  into  the  inner  border  of  the  acromion  and  spine  of  the 
scapula ;  the  lower  terminate  in  a  thin  tendon,  which  plays  over 
the  triangular  surface  at  the  back  of  the  scapula,  and  is  inserted 
into  the  beginning  of  the  spine.  The  insertion  of  the  trapezius 
exactly  corresponds  to  the  origin  of  the  deltoid,  and  the  two 
muscles  are  connected  by  a  thin  aponeurosis  over  the  spine  and 
acromion.  If  both  the  trapezius  muscles  be  exposed,  observe  that, 
between  the  sixth  cervical  and  the  third  dorsal  vertebras,  their 
origin  presents  an  aponeurotic  space  of  an  elliptical  form. 

The  structures  covered  by  the  trapezius  are,  the  splenius,  the 
complexus,  the  levator  anguli  scapulas,  the  rhomboidei  minor  and 
major,  the  supra-spinatus,  a  small  part  of  the  infra-spinatus,  the 
longissimus  dorsi,  the  sacro-lumbalis,  the  spinal  accessory  nerve, 
and  the  superficialis  colli  artery. 

*  The  ligamentum  nuchse  is,  in  man,  only  a  rudiment  of  the  great  elastic  ligament 
which  supports  the  weight  of  the  head  in  quadrupeds.  It  extends  from  the  spine  of 
the  occiput  to  the  spines  of  all  the  cervical  vertebrae,  except  the  atlas  ;  otherwise  it 
would  impede  the  free  rotation  of  the  head.  In  the  giraffe  this  ligament  is  six  feet 
long,  and  ae  thick  as  a  man's  forearm.  Professor  Quekett  states  that  when  divided  it 
shrinks  at  least  two  feet. 


312  SUPERFICIAL   MUSCLES    OF    THE    BACK. 

The  fixed  point  of  the  muscle  being  at  the  vertebral  column, 
all  its  fibres  tend  to  raise  the  shoulder.  The  deltoid  cannot  raise 
the  humerus  beyond  an  angle  of  ninety  degrees :  beyond  this,  the 
elevation  of  the  arm  is  principally  effected  by  the  rotatory  move- 
ment of  the  scapula.  The  trapezius  is  in  strong  action  when  a 
weight  is  borne  upon  the  shoulders ;  again,  its  middle  and  inferior 
fibres  act  powerfully  in  drawing  the  scapula  backwards,  as  in 
preparing  to  strike  a  blow.  If  both  muscles  act,  they  draw  the 
head  backwards ;  if  one  only  acts,  it  draws  the  head  to  the  same 
side.  It  is  supplied  by  the  nervus  accessorius  and  the  cervical 
plexus,  and  by  the  superficial!  s  colli  artery. 

LATISSIMUS  This  broad  flat  muscle  occupies  the  lumbar  and 

DORSI.  lower   dorsal  region,  and  thence  extends  to   the 

arm,  where  it  forms  part  of  the  posterior  boundary  of  the  axilla. 
It  arises  from  the  posterior  third  of  the  external  lip  of  the  crest 
of  the  ilium,  from  the  spinous  processes  of  the  two  upper  sacral, 
all  the  lumbar  and  the  six  lower  dorsal  vertebrae,  by  a  strong 
aponeurosis  ;  and,  lastly,  from  the  three  or  four  lower  ribs  by  fleshy 
slips,  which  interdigitate  with  those  of  the  external  oblique  muscle 
of  the  abdomen.  All  the  fibres  converge  towards  the  axilla,  where 
they  form  a  thick  muscle,  which  curves  round  the  inferior  angle 
of  the  scapula,  and  is  inserted  by  a  broad,  flat  tendon,  into  the 
bottom  of  the  "bicipital  groove  of  the  humerus.  The  tendon  is 
about  two  inches  broad,  and  lies  in  front  of  and  higher  than  that 
of  the  teres  major,  from  which  it  is  separated  by  a  large  bursa.* 
It  is  supplied  mainly  by  the  long  subscapular  nerve,  also  by  the 
posterior  branches  of  the  dorsal  and  lumbar  nerves. 

The  latissimus  dorsi  draws  the  humerus  inwards  and  back- 
wards ;  rotating  it  also  inwards.  It  co-operates  with  the  pectoralis 
major  in  pulling  any  object  towards  the  body :  if  the  humerus  be 
the  fixed  point,  it  raises  the  body,  as  in  climbing.  The  object  of 
the  muscle  arising  so  high  up  the  back  is,  that  the  transverse 
fibres  of  the  muscle  may  strap  down  the  inferior  angle  of  the 
scapula.  It  sometimes  happens  that  the  scapula  slips  above  the 

*  The  latissimus  dorsi  frequently  receives  a  distinct  accessory  slip  from  the  inferior 
angle  of  the  scapula. 


SUPERFICIAL  MUSCLES  OF  THE  BACK.          813 

muscle  :  this  displacement  is  readily  recognised  by  the  unnatural 
projection  of  the  lower  angle  of  the  bone,  and  the  impaired  move- 
ments of  the  arm.* 

The  muscles  lying  beneath  the  latissimus  dorsi  are, — a  small 
part  of  the  rhomboideus  major,  of  the  infra-spinatus,  and  of  the 
teres  major,  the  serratus  posticus  inferior,  the  spinalis  dorsi,  the 
longissimus  dorsi,  the  sacro-lumbalis,  and  the  external  intercostals. 
Between  the  base  of  the  scapula,  the  trapezius,  and  the  upper 
border  of  the  latissimus  dorsi,  a  triangular  space  is  observed  when 
the  arm  is  raised,  in  which  the  lower  fibres  of  the  rhomboideus 
major  and  part  of  the  sixth  intercostal  space,  are  exposed.  Im- 
mediately above  the  crest  of  the  ilium,  between  the  free  margins  of 
the  latissimus  dorsi  and  external  oblique,  there  is,  also,  an  interval 
in  which  a  little  of  the  internal  oblique  can  be  seen. 

LUMBAB  This    dense   shining   aponeurosis    of    the   back 

APONEUBOSIS.  (sometimes  termed  the  aponeurosis  of  the  latissi- 

mus dorsi)  forms  the  posterior  part  of  the  sheath  of  the  erector 
spinse.  It  is  pointed  above,  where  it  is  continuous  with  the  deep 
cervical  fascia,  broader  and  stronger  below.  It  consists  of  ten- 
dinous fibres,  which  are  attached  internally  to  the  spines  of  the  six 
or  seven  lower  dorsal,  all  the  lumbar  and  sacral  vertebrae  ;  exter- 
nally, to  the  angles  of  the  ribs ;  and  inferiorly  it  is  blended  with 
the  tendons  of  the  serratus  posticus  inferior  and  latissimus  dorsi. 
When  suppuration  takes  place  in  the  loins,  constituting  a  lumbar 
abscess  in  connection  with  spinal  disease,  the  pus  is  seated 
beneath  this  aponeurosis,  and  is  therefore  tardy  in  coming  to  the 
surface. 

Reflect  the  trapezius  from  its  insertion.     On  its 

DISSECTION. 

under  surface  see  the  ramifications  of  its  nutrient 
artery,  the  superficialis  colli,  a  branch  of  the  posterior  scapular. 
A  large  nerve,  the  spinal  accessory,  enters  its  under  surface  near 

*  We  hare  seen  several  instances  of  this  displacement.  There  is  great  projection 
of  the  inferior  angle  of  the  scapula,  especially  when  the  patient  attempts  to  raise  the 
arm.  He  cannot  raise  the  arm  beyond  a  right  angle,  unless  firm  pressure  is  made 
on  the  lower  angle  of  the  scapula,  so  as  to  supply  the  place  of  the  muscular  strap. 
Whether  the  scapula  can  be  replaced  or  not,  a  firm  bandage  should  be  applied  round 
the  chest. 


314          SUPERFICIAL  MUSCLES  OF  THE  BACK. 

the  clavicle,  and  divides  into  filaments,  which,  reinforced  by  fila- 
ments from  the  third  and  fourth  cervical  nerves,  are  distributed 
to  the  muscle  as  far  as  its  lower  border. 

SPINAL  ACCES-  This  nerve  is  one  of  the  three  divisions  of  the 

SORT  NERVE.  eighth  pair  of  cerebral  nerves.     It  arises  from  the 

lateral  part  of  the  cervical  portion  of  the  spinal  cord  by  several 
roots,  some  of  which  are  as  low  as  the  sixth  cervical  vertebra. 
Formed  by  the  union  of  these  roots,  the  nerve  enters  the  skull 
through  the  foramen  magnum,  and  leaves  it  again  through  the 
foramen  jugulare.  It  then  runs  behind  the  internal  jugular  vein, 
traverses  obliquely  the  upper  third  of  the  sterno-mastoid,  and 
crosses  the  posterior  triangle  of  the  neck  to  the  trapezius,  which  it 
supplies  (p.  19). 

Beneath  the  trapezius  we  have  to  examine  the  second  layer, 
consisting  of  three  muscles  connected  with  the  scapula ;  namely, 
the  levator  anguli  scapulae,  the  rhomboideus  major  and  minor. 
The  scapula  should  be  adjusted  so  as  to  stretch  their  fibres. 

LEVATOR  AN-  This  muscle  is  situated  at  the  side  of  the  neck. 

GULI  SCAPULA.  It  arises  by  four  tendons  from  the  posterior 
tubercles  of  the  transverse  processes  of  the  four  upper  cervical 
vertebrae.  The  muscular  slips  to  which  the  tendons  give  rise  form 
a  single  muscle,  which  descends  along  the  side  of  the  neck,  and  is 
inserted  into  the  posterior  border  of  the  scapula  between  its  spine 
and  superior  angle.  Its  action  is  to  raise  the  posterior  angle  of 
the  scapula  ;  as,  for  instance,  in  shrugging  the  shoulders.  Its 
nerve  comes  from  the  fifth  cervical. 

EHOMBOIDEUS  These  flat  muscles  extend  from  the  spinous  pro- 

MAJOR  AND  cesses  of  the  vertebrae  to  the  base  of  the  scapula. 

MINOR.  They  often  appear    like  a    single  muscle.      The 

rhomboideus  minor,  the  higher  of  the  two,  arises  by  a  thin  apo- 
neurosis  from  the  spinous  processes  of  the  last  cervical  and  the  first 
dorsal  vertebra,  and  is  inserted  into  the  base  of  the  scapula  oppo- 
site its  spine.  The  rhomboideus  major  arises  by  tendinous  fibres 
from  the  spinous  processes  of  the  four  or  five  upper  dorsal  vertebrae, 
and  is  inserted  by  fleshy  fibres  into  the  base  of  the  scapula  between 
its  spine  and  inferior  angle ;  the  larger  number  of  the  fibres  being 


SUPRA-SCAPULAR    ARTERY.  315 

inserted  into  a  tendinous  arch,  which  is  chiefly  attached  to  the 
inferior  angle.  The  action  of  these  muscles  is  to  draw  the  scapula 
upwards  and  backwards.  They  are  the  antagonists  of  the  serratus 
magnus. 

The  nerve  of  the  rhomboid  muscles  (posterior  scapular)  is  a 
branch  of  the  fifth  cervical.  It  passes  outwards  beneath  the  lower 
part  of  the  levator  anguli  scapula,  to  which  it  sends  a  branch,  and 
is  lost  in  the  under  surface  of  the  rhomboidei. 

This  muscle  extends  from  the  scapula  to  the 

OMO-HTOIDEUS.  .  . 

os  hyoides,  and  consists  ot  two  long  narrow  mus- 
cular portions,  connected  by  an  intermediate  tendon  beneath  the 
sterno-mastoid.  The  posterior  portion  only  can  be  seen  in  the 
present  dissection.  It  arises  from  the  upper  border  of  the  scapula, 
close  behind  the  notch,  and  from  the  ligament  above  the  notch. 
Thence  the  slender  muscle  passes  forwards  across  the  lower  part  of 
the  neck,  beneath  the  sterno-mastoid,  where  it  changes  its  direc- 
tion and  ascends  nearly  vertically,  to  be  attached  to  the  os  hyoides 
at  the  junction  of  the  body  with  the  greater  cornu  (p.  29).  Thus 
the  two  portions  of  the  muscle  form,  beneath  the  sterno-mastoid, 
an  obtuse  angle,  of  which  the  apex  is  tendinous,  and  of  which  the 
angular  direction  is  maintained  by  a  layer  of  fascia,  proceeding 
from  the  tendon  to  the  first  rib  and  the  clavicle,  Its  action  is  to 
depress  the  os  hyoides.  Its  nerve  comes  from  the  descendens 
noni  (p.  30). 

SUPKA-SCAPU-  This  artery  (transversalis  humerj),  a  branch  of 

LAB  AETEET.  the  thyroid  axis  (p.  67),  runs  behind  and  parallel 

with  the  clavicle,  over  the  lower  end  of  the  acalenus  anticus  to  the 
upper  border  of  the  scapula,  where  it  usually  passes  above  the 
ligament  bridging  over  the  notch.  It  ramifies  in  the  supra- 
spinous  fossa,  supplying  the  supra-spinatus.,  and  then  passes  under 
the  acromion  to  the  infra-spinous  fossa.,  where  it  inosculates 
freely  with  the  dorsalis  scapulae,  a  branch  of  the  subscapular.  It 
sends  off — 

a.  The  supra-acromial  branch,  which  ramifies  upon  the  acromion, 
anastomosing  with  the  other  acromial  arteries  derived  from  branches  of 
the  axillary ;  b.  a  small  subscapular  branch  to  the  fossa  of  the  same 


316  SERRATUS    MAGNUS. 

name ;  c.  articular  arteries  to  the  shoulder  joint ;  and,  lastly,  d.  the 
infra-spinous  branch,  which  anastomoses  with  the  dorsalis  scapulas. 
The  supra-scapular  vein  terminates  either  in  the  subclavian  or  in  the 
external  jugular. 

The  supra-scapular  nerve,  a  branch  of  the  fifth,  and  some- 
times the  sixth,  cervical,  runs  with  the  corresponding  artery,  and 
after  passing  through  the  supra-scapular  notch,  is  distributed  to 
the  supra-spinatus  and  infra-spinatus.  In  the  supra-spinous  fossa, 
this  nerve  sends  a  small  branch  to  the  shoulder-joint. 

POSTERIOR  This  artery  is  one  of  the  divisions  of  the  trans- 

SCAPULAR  versalis  colli,  but  comes  very  frequently  from  the 

ARTERY.  subclavian  in  the  third  part  of  its  course  (p.  67). 

It  runs  across  the  lower  part  of  the  neck,  above,  or  between  the 
nerves  of  the  brachial  plexus,  towards  the  posterior  superior  angle 
of  the  scapula.  Here  it  pursues  its  course  along  the  posterior 
border  of  the  scapula  beneath  the  levator  anguli  scapulae  and  the 
rhomboidei,  anastomosing  with  branches  of  the  supra-scapular  and 
sub-scapular  arteries.  The  corresponding  vein  joins  the  external 
jugular  or  the  subclavian. 

Divide  the  rhomboid  muscles  near  their  inser- 
tion, and  trace  the  artery  to  the  inferior  angle 
of  the  scapula,  where  it  terminates  in  the  rhomboidei,  serratus 
inagnus,  and  latissimus  dorsi. 

Numerous  muscular  branches  arise  from  the  posterior  scapular. 
The  superficialis  colli  (the  other  division  of  the  transversalis  colli) 
is  given  off  near  the  upper  angle  of  the  scapula  for  the  supply  of 
the  trape/ius. 

Divide  and  reflect  the  latissimus  dorsi  below  the  inferior  angle 
of  the  scapula,  and  draw  the  scapula  forcibly  outwards,  to  have  a 
more  perfect  view  of  the  extent  of  the  serratus  inagnus,  than  was 
seen  in  the  axilla.  The  abundance  of  connective  tissue  in  this 
situation  is  necessary  for  the  play  of  the  scapula  on  the  chest. 

SERRATUS  This  broad  flat  muscle  intervenes  between  the 

MAGNUS.  scapula  and  the  ribs.     It  arises  by  nine  fleshy 

digitations  from  the  eight  upper  ribs,  each  rib  giving  origin  to  one, 
and  the  second  to  two.  The  four  lower  digitations  correspond  with 


MUSCLES    OP    THE    SHOULDEK.  317 

those  of  the  external  oblique  muscle  of  the  abdomen.  All  the 
fibres  pass  backwards,  and  converge  to  be  inserted  along  the  inner 
side  of  the  posterior  border  of  the  scapula,  chiefly  near  the  upper 
and  lower  angles. 

This  is  the  most  important  of  the  muscles  which  regulate  the 
movements  of  the  scapula.  It  draws  the  scapula  forwards,  and 
thus  gives  additional  reach  to  the  arm  ;  it  counteracts  all  forces 
which  tend  to  push  the  scapula  backwards  ;  for  instance,  when  a 
man  falls  forwards  upon  his  hands,  the  serratus  magnus  sustains 
the  shock,  and  prevents  the  scapula  from  being  driven  back  to  the 
spine.  Supposing  the  fixed  point  to  be  at  the  scapula,  some 
anatomists  ascribe  to  it  the  power  of  raising  the  ribs  ;  hence  Sir 
Charles  Bell  called  it  the  external  respiratory  muscle,  the  in- 
ternal respiratory  muscle  being  the  diaphragm. 

The  nerve  which  supplies  it  is  a  branch  of  the  fifth  and  sixth 
cervical  nerve  :  it  descends  along  its  outer  surface^  distributing  a 
filament  to  each  digitation  of  the  muscle  (p.  271). 

Divide  the  serratus  magnus  near  the  scapula, 
and  remove  the  arm  by  sawing  through  the  middle 
of  the  clavicle,  cutting  through  the  axillary  vessels  and  nerves. 
These  should  be  tied  to  the  coracoid  process.  After  the  removal 
of  the  arm,  examine  the  precise  insertions  of  the  preceding 
muscles. 


DISSECTION   OF  THE  MUSCLES   OF  THE  SHOULDEK. 

Dissect    first    the     cutaneous    nerves    of    the 
DISSECTION. 

CUTANEOUS  shoulder ;    these    are    derived,   partly   from   the 

NERVES  OF  THE  acromial  branches  of  the  cervical  plexus  which 
SHOULDEK.  descend  over  the  acromion  (fig.  59),  partly  from 

the  circumflex  nerve,  of  which  one  or  two  branches  turn  round  the 
posterior  border  of  the  deltoid  ;  others  perforate  the  muscle,  each 
accompanied  by  a  small  artery. 

Notice  the  strong  layer    of  fascia  upon    the  surface  of  the 
deltoid,  which  extends  from  the  aponeurosis  covering  the  muscles 


318 


THE    DELTOID. 


on  the  back  of  the  scapula,  and  is  continuous  with  the  fascia  of 
the  arm.  It  dips  down  between  the  fibres  of  the  muscle,  dividing 
it  into  large  bundles.  This  fascia  must  be  removed. 

The  large  muscle  which  covers  the  shoulder- 
joint  is  named  deltoid,  from  its  resemblance  to  the 
Grreek  A  reversed.  It  arises  from  the  external  third  of  the 
clavicle,  from  the  acromion,  and  from  the  spine  of  the  scapula 

FIG.  59. 


DELTOID. 


1.  Supra-acromial  br.  of  the 

cervical  nerves. 

2.  Ascending  and  descend- 

ing brs.  of  the  circum- 
flex n. 

3.  4.  Cutaneous  brs.  of  the 

musculo-cutaneous  n. 

5.  Internal  cutaneous  br.  of 
musculo-spiral  n. 


6.  Intercosto-humeral 

brs. 

7.  Filaments  of  the  lesser 

internal  cutaneous  n. 

8.  Posterior      cutaneous 

br.  of  internal  cuta- 
neous n. 

9.  Branch  of  internal  cu- 

taneous n. 


CUTANEOUS  NERVES  OF  THE  LEFT  SHOULDER  AND  ARM.   (POSTERIOR  VIEW.) 

down  to  the  triangular  surface  at  its  root.  This  origin,  which' 
corresponds  to  the  insertion  of  the  trapezius,  is  tendinous  and 
fleshy  everywhere,  except  at  the  commencement  of  the  spine  of  the 
scapula,  where  it  is  simply  tendinous,  and  connected  with  the 
infra-spinous  aponeurosis.  The  muscular  fibres  descend,  the  .an- 
terior backwards,  the  posterior  forwards,  the  middle  perpendicu- 
larly ;  all  converge  to  a  tendon  which  is  inserted  into  a  rough 


THE    DELTOID. 


319 


surface  on  the  outer  side  of  the  humerus,  a  little  above  the  middle 
of  the  shaft.  The  insertion  of  the  tendon  extends  one  inch  and  a 
half  along  the  humerus,  and  terminates  in  a  V-shaped  form,  the 
origin  of  the  brachialis  anticus  embracing  it  on  either  side. 
Sometimes  a  few  fibres  of  the  pectoralis  major  are  connected  with 
its  front  border. 

The  muscular  bundles  composing  the  deltoid  have  a  peculiar 
arrangement :  a  peculiarity  arising  from  its  broad  origin  and  its 
narrow  insertion.  It  consists  in  the  interposition  of  tendons 
between  the  bundles  for  the  attachment  of  the  muscular  fibres. 
The  annexed  woodcut  shows  this  arrangement  better  than  any 
description.  The  action  of  the  muscle  is  not  only  concentrated 
upon  one  point,  but  its  power  is  also  greatly  increased  by  this 
arrangement. 

ACTION  OF  THE          It  raises  the  arm  ;  but  it  cannot  do  so  beyond 
DELTOID.  an  angle  of  ninety  degrees.     The  elevation  of  the 

arm    beyond  this   angle   is    effected  through  the  raising  of  the 
shoulder  by  the  trapezius  and  ser- 
ratus  magnus.     Its  anterior  fibres 
draw  the  arm  forwards ;    its   pos- 
terior, backwards. 

This  powerful  muscle  is  supplied 
with  blood,  by  the  anterior  and 
posterior  circumflex,  the  thoracica 
humeraria,  the  thoracica  acromi- 
alis,  all  from  the  axillary  artery ; 
also  by  the  deltoid  branch  of  the 
brachial.  Its  nerve  is  the  circumflex. 

The  rotundity  of  the  shoulder  is 
due  not  so  much  to  the  deltoid  as 
to  the  upper  end  of  the  humerus. 
When  the  head  of  the  humerus  is 
dislocated  into  the  axilla,  the  fibres 
of  the  muscle  run  vertically  to 
their  insertion;  hence  the  flatten- 
ing of  the  deltoid,  and  the  greater  prominence  of  the  acromion. 


FIG.  60. 


ANALYSIS    OF   THE    DELTOID. 


320  CIRCUMFLEX    AETERT    AND    NERVE. 

It  is  below  the  deltoid  that  an  ununited  fracture  of  the 
humerus  is  most  commonly  met  with,  owing  to  the  muscle  dis- 
placing the  upper  fragment. 

Eeflect  the  deltoid  from  its  origin,  and  turn  it 
downwards.  Observe  the  ramifications  of  the 
circumflex  nerve  and  the  anterior  and  posterior  circumflex 
arteries,  on  its  under  surface  :  notice  also  the  large  bursa  between 
it  and  the  tendons  inserted  into  the  great  tuberosity  of  the 
humerus.  The  muscle  covers  the  coraco-acromial  ligament,  the 
head,  neck,  and  upper  part  of  the  humerus,  as  well  as  the  coraco- 
brachialis  and  biceps,  the  pectoralis  minor,  the  supra-spinatus,  the 
infra-spinatus,  and  teres  minor,  the  subscapularis  and  the  long 
head  of  the  triceps. 

BURSA  UNDUE  The  large  bursa  under  the  deltoid  extends  for 

THE  DELTOID,  OR  some  distance  beneath  the  acromion  and  the 
SUB-ACROMIAL.  coraco-acromial  ligament,  and  covers  the  tendons 
attached  to  the  great  tuberosity  of  the  humerus.  It  communi- 
cates, very  rarely,  with  the  shoulder-joint.  Its  use  is  to  facilitate 
the  movements  of  the  head  of  the  bone  under  the  acromial  arch. 

POSTERIOR  This  artery  is  given  off  from  the  axillary :   it 

CIRCUMFLEX  runs  behind  the  surgical  neck   of  the  humerus, 

ARTERY.  through  a  quadrilateral  opening,  bounded  above 

by  the  subscapularis  and  teres  minor,  below  by  the  teres  major, 
externally  by  the  neck  of  the  humerus,  and  internally  by  the  long 
head  of  the  triceps  (p.  266).  Its  branches  terminate  on  the  under 
surface  of  the  deltoid,  anastomosing  with  the  anterior  circumflex, 
acromial  thoracic,  and  supra-scapular  arteries. 

From  the  posterior  circumflex,  a  branch  descends  in  the  sub- 
stance of  the  long  head  of  the  triceps,  to  inosculate  with  the 
superior  profunda  ;  this  is  one  of  the  channels  through  which  the 
circulation  would  be  carried  on,  if  the  axillary  were  tied  in  the  last 
part  of  its  course. 

CIRCUMFLEX  This  nerve,  a  branch  of  the  posterior  cord  of  the 

NERVE.  axillary  plexus,  runs  with  the  posterior  circumflex 

artery.  It  sends  a  branch  to  the  teres  minor,  one  or  two  to  the 
integuments  of  the  shoulder,  and  terminates  in  the  substance  of 


MUSCLES    OF    THE    SCAPULA.  321 

the  deltoid.  The  proximity  of  this  nerve  to  the  head  of  the 
humerus  explains  the  occasional  paralysis  of  the  deltoid,  after  dis- 
location or  fracture  of  the  humerus.  The  nerve  is  liable  to  be 
injured,  if  not  actually  lacerated,  by  the  pressure  of  the  bone.  In 
the  summer  of  1840,  a  man  was  admitted  into  the  hospital  with  a 
severe  injury  to  the  shoulder,  and  died  of  delirium  tremens.  On 
examination  the  humerus  was  found  broken  high  up,  the  capsule 
of  the  joint  opened,  and  the  circumflex  nerve  torn  completely 
across.* 

A  strong  aponeurosis  covers  the  muscles  of  the  dorsum  of  the 
scapula,  and  is  firmly  attached  to  the  spine  and  borders  of  the 
bone.  At  the  posterior  edge  of  the  deltoid,  it  divides  into  two 
layers,  one  of  which  passes  over,  the  other  under,  the  muscle. 
Eemove  the  aponeurosis,  so  far  as  it  can  be  done  without  injury  to 
the  muscular  fibres  which  arise  from  its  under  surface. 

INFRA.  This  muscle  arises  from  the  posterior  two-thirds 

SPINATUS.  of  the  infra-spinous  fossa,  and  from  the  aponeu- 

rosis which  covers  it.  The  fibres  converge  to  a  tendon,  which  is  at 
first  contained  in  the  substance  of  the  muscle,  and  then  proceeds 
over  the  capsule  of  the  shoulder-joint  to  be  inserted  into  the 
middle  depression  on  the  greater  tuberosity  of  the  bumerus.  Its 
nerve  comes  from  the  supra-scapular. 

This  long  narrow  muscle  is  situated  below  the 
TBEES  MINOE.         .    ~  .  ,  , ,        .    ,.     .        ,       ,          ~    , , 

mfra-spmatus,  along   the    inferior  border  of  the 

scapula.  It  arises  from  the  dorsum  of  the  scapula,  close  to 
the  inferior  border,  and  from  the  intermuscular  septa  between  it 
and  the  infra-spin atus  above  and  the  teres  major  below.  The 
fibres  ascend  parallel  with  those  of  the  infra- spinatus,  and  termi- 
nate in  a  tendon,  which  passes  over  the  capsule  of  the  shoulder- 
joint,  and  is  inserted  into  the  lowest  depression  on  the  great 
tuberosity  of  the  humerus,  and  by  muscular  fibres  into  the  bone 
below  it.  It  is  supplied  by  a  branch  of  the  circumflex  nerve, 
which  has  (usually)  a  small  ganglion-like  enlargement  upon  it. 

The  action  of  the  infra-spinatus  and  teres  minor  is  to  rotate 
the  humerus  outwards. 

*  See  preparation  in  Museum  of  St.  Bartholomew's  Hospital,  series  3,  No.  42. 

Y 


MUSCLES   OF    THE    SCAPULA. 

This  muscle  is  closely  connected  with  the  latis- 
simus dorsi,  and  extends  from  the  inferior  angle 
of  the  scapula  to  the  immerus,  contributing  to  form  the  posterior 
boundary  of  the  axilla.  It  arises  from  the  flat  surface  at  the 
inferior  angle  of  the  back  of  the  scapula,  from  its  inferior  border, 
and  the  intermuscular  septa,  and  terminates  upon  a  flat  tendon, 
nearly  two  inches  in  breadth^  which  is  inserted  into  the  inner 
edge  of  the  bicipital  groove  of  the  humerus,  behind  and  a  little 
lower  than  the  tendon  of  the  latissimus  dorsi.  Its  action  is  to 
draw  the  humerus  backwards.  It  is  supplied  by  the  middle  sub- 
scapular  nerve. 

A  bursa  is  found  in  front  of,  and  another  behind  the  tendon  of 
the  teres  major;  t-he  former  separates  it  from  the  latissimus  dorsi, 
the  latter  from  the  bone. 

SUPRA-  This  muscle  arises  from  the  posterior  two-thirds 

SMNATUS.  of  the  supra-spinous  fossa,  and-from  its  aponeurotic 

covering.  It  passes  under  the  acromion,  over  the  shoulder-joint, 
and  is  inserted  by  a  strong  tendon  into  the  superior  depression  of 
the  greater  tuberosity  of' the  humerus.  To  see  its  insertion,  the 
acromion  should  be  sawn  off  near  the  neck  of  the  scapula.  Its 
action  is  to  assist  the  deltoid  in  raising  the  arm.  Its  nerve  is 
derived  from  the  supra-scapular. 

This  muscle  occupies  the  stibscapular  fossa.     It 

SUBSCAPULARIS.  ,  „  ,  „ 

arises  from  the  posterior  three-fourths  ot  the 
fossa,  and  from  three  or  four  tendinous  septa  attached  to  the 
oblique  bony  ridges  on  its  surface.  The  fibres  converge  towards 
the  neck  of  the  scapula,  where  they  terminate  upon  three  or  four 
tendons,  which  are  concealed  amongst  the  muscular  fibres,  and  are 
inserted  into  the  lesser  tuberosity  of  the  humerus.  Its  broad  in- 
sertion is  closely  connected  with  the  capsule  of  the  shoulder-joint, 
which  it  completely  protects  upon  its  inner  side.  Its  action  is  to 
rotate  the  humerus  inwards.  The  nerves  which  supply  it  come 
from  the  long  and  middle  subscapular  nerves. 

The  coracoid  process,  with  the  coraco-brachialis  and  short  head 
of  the  biceps,  forms  an  arch,  under  which  the  tendon  of  the  sub- 
scapularis  plays.  There  are  several  bursce  about  the  tendon. 


TEICEPS    EXTENSOR   CUBITI.  323 

One,  of  considerable  size,  on  the  upper  surface  of  the  tendon,  facili- 
tates its  motion  beneath  the  coracoid  process  and  the  coraco- 
brachialis:  this  sometimes  communicates  with  the  large  bursa 
under  the  deltoid.  Another  is  situated  between  the  tendon  and  the 
capsule  of  the  joint,  and  almost  invariably  communicates  with  it. 

Now  reflect  the  muscles  from  the  surfaces  of  the 

scapula,  to  trace  the  arteries  which  ramify  upon  it. 

CONTINUATION  This  artery,  a  branch  of  the  thyroid  axis,  runs 

OF  SDPRA-SCAPU-       under  and  parallel  with  the  clavicle,  and  passes 

LAB  ARTERY  AND      above  the  notch  of  the  scapula,  into  the  supra- 

spinous  fossa :    it  sends  a  branch  to  the  supra- 

spinatus,  another  to  the  shoulder-joint,  and  then  descends  behind 

the  neck  of  the  scapula  into  the  fossa  below  the  spine,  where   it 

inosculates    directly  with    the    dorsalis    scapulae.      Its    branches 

ramify  upon  the  bone,  and  supply  the  infra-spinatus  and  teres 

minor. 

The  supra-scapular  nerve  passes  most  frequently  through  the 
notch  of  the  scapula,  accompanies  the  corresponding  artery,  sup- 
plies the  supra-spinatus  with  two  branches,  and  then  enters  the 
infra-spinous  fossa,  to  terminate  in  the  infra-spinatus. 

DORSALIS  This  artery,  after  passing  through  the  triangular 

SCAPULA  ARTERY,  space  (p.  266),  curves  round  the  inferior  border  of 
the  scapula,  which  it  grooves,  to  the  infra-spinous  fossa,  where  it 
ascends  close  to  the  bone,  and  anastomoses  with  the  supra  and 
posterior  scapular  arteries. 

The  several  communications  about  the  scapula  between  the 
branches  of  the  subclavian  and  axillary  arteries,  would  furnish  a 
large  collateral  supply  of  blood  to  the  arm,  if  the  subclavian  were 
tied  above  the  clavicle  (p.  69). 

TRICEPS  EXTEN-         This  muscle,  which  arises  by  three  heads,  and 
SOR  CUBITI.  was  oniy  partially  seen  in  the  dissection  of  the 

upper  arm  (p.  284),  should  now  be  thoroughly  examined.  The 
long  head  arises  immediately  below  the  glenoid  cavity  of  the 
scapula,  by  a  strong  tendon,  which  is  connected  with  the  capsule 
of  the  shoulder-joint.  The  external  head  arises  from  the 
posterior  part  of  the  humerus,  below  the  insertion  of  the  teres 

Y    2 


324  TRICEPS   EXTENSOR   CUBITI. 

minor,  as  far  as  the  musculo-spiral  groove.  The  internal  head 
arises  from  the  posterior  part  of  the  humerus,  below  the  teres 
major  and  the  musculo-spiral  groove,  as  far  as  the  olecranon  fossa ; 
it  has  an  additional  origin  from  the  internal  intermuscular  septum, 
and  from  a  small  portion  of  the  external.  The  precise  origin 
of  these  heads  from  the  humerus,  may  be  ascertained  by  following 
the  superior  profunda  artery  and  musculo-spiral  nerve,  which 
separate  them.  The  three  portions  of  the  muscle  terminate  upon 
a  broad  tendon,  which  covers  the  back  of  the  elbow-joint,  and  is 
inserted  into  the  summit  and  sides  of  the  olecranon ;  it  is  also  con- 
nected with  the  fascia  on  the  back  of  the  forearm.  The  effect  of 
this  connection  is  that  the  same  muscle  which  extends  the  fore- 
arm tightens  the  fascia  which  gives  origin  to  the  extensors  of  the 
wrist  and  fingers.  The  same  holds  good  in  the  case  of  the  biceps, 
and  its  semi-lunar  expansion  in  the  fascia  of  the  forearm. 

Between  the  tendon  and  the  olecranon  is  a  bursa,  commonly 
of  small  size,  but  sometimes  so  large  as  to  extend  upwards  behind 
the  capsule  of  the  joint.  This  bursa  must  not  be  mistaken  for  the 
subcutaneous  one,  which  is  situated  between  the  skin  and  the 
olecranon,  and  is  so  often  injured  by  a  fall  on  the  elbow. 

By  dividing  the  triceps  transversely  a  little 
above  the  elbow,  and  turning  down  the  lower  por- 
tion, it  will  be  seen  that  some  of  the  muscular  fibres  terminate 
upon  the  capsule  of  the  joint.  They  have  been  described  by  some 
anatomists  as  a  distinct  muscle,  under  the  name  of  sub-anconeus  ; 
their  use  is  to  draw  up  the  capsule,  so  that  it  may  not  be  injured 
during  extension  of  the  arm.  The  sub-anconeus  is  in  this  respect 
analogous  to  the  sub-eruraeus  muscle  of  the  thigh.  Observe  the 
bursa  under  the  tendon,  and  the  arterial  arch  formed  upon  the 
back  part  of  the  capsule  by  the  superior  profunda  and  the  anasto- 
motica  magna  (fig.  61,  p.  334). 

Trace  the  continuation  of  the  superior  profunda  artery  (p.  279) 
and  museulo-spiral  nerve  round  the  posterior  part  ef  the  humerus. 
They  lie  in  a  slight  groove  on  the  bone,*  between  the  external 

*  It  is  worth  remembering  that  the  nerve  may  be  injured  by  a  fracture  of  the 
humerus  in  this  situation,  and  even  by  too  tight  bandaging  ;  the  result  being  para- 
lysis of  the  extensor  muscles  of  the  forearm. 


DISSECTION    OP    THE    BACK    OF    THE    FOREARM.  325 

and  internal  heads  of  the  triceps,  and  are  protected  by  an  aponeu- 
rotic  arch,  thrown  over  them  by  the  external  head  of  the  triceps. 
After  supplying  the  muscles,  the  artery  continues  its  course  along  the 
outer  side  of  the  arm  between  the  brachialis  anticus  and  supinator 
radii  longus,  and  inosculates  with  the  radial  recurrent.  It  gives  off  a 
branch,  which  runs  down  between  the  triceps  and  the  bone,  and 
inosculates,  at  the  back  of  the  elbow,  with  the  anastomotica  magna 
and  posterior  interosseous  recurrent.  The  musculo-spiral  nerve 
which  accompanies  the  artery  sends  branches  to  supply  the  three 
portions  of  the  triceps,  the  supinator  radii  longus,  and  extensor 
carpi  radialis  longior.*  It  then  divides  into  the  posterior  inter- 
osseous  and  radial  nerves.  The  small  nerve  must  be  made  out 
which  runs  down  the  substance  of  the  triceps,  accompanied  by  a 
branch  from  the  superior  profunda  artery,  to  supply  the  anconeus. 
The  cutaneous  branches  of  the  musculo-spiral  nerve  have  been 
already  dissected  (p.  272). 


DISSECTION   OF   THE  BACK    OF  THE   FOREARM. 

SUBCUTANEOUS  Remove  the  skin  from  the  back  of  the  forearm, 

BUES^E.  hand,  and  fingers,  and  make  out  the  subcutaneous 

bursa  over  the  olecranon.  It  is  of  considerable  size,  and,  if  dis- 
tended, would  appear  nearly  as  large  as  a  walnut.  Another  bursa 
is  sometimes  found  a  little  lower  down  upon  the  ulna.  A  sub- 
cutaneous bursa  is  generally  placed  over  the  internal  condyle, 
another  over  the  external.  A  bursa  is  also  situated  over  the 
styloid  process  of  the  ulna  ;  this  sometimes  communicates  with 
the  sheath  of  the  extensor  carpi  ulnaris.  Small  bursce  are  some- 
times developed  in  the  cellular  tissue  over  each  of  the  knuckles. 

The  cutaneous  veins,  from  the  back  of  the  hand  and  forearm, 
join  the  venous  plexus  at  the  bend  of  the  elbow  (see  p.  273). 

The  cutaneous  nerves  of  the  back  of  the  fore- 

(JUTANEOUS 

NEBVES  OF  THE  arm,  are  derived  from  the  external  cutaneous 
BACK  OF  THE  branches  of  the  musculo-spiral,  from  branches  of 

FOREABM.  ^e  i^nial  cutaneous,  and  of  the  external  cuta- 

*  The  brachialis  anticus  usually  receives  a  branch  from  the  musculo.^piral  nerve. 


326  DISSECTION    OF   THE    BACK   OF    THE    FOKEAEM. 

neous.  The  greater  number  of  these  nerves  may  be  traced  down 
to  the  back  of  the  wrist. 

The  skin  on  the  back  of  the  hand  is  united  to 
NERVES  ON  THE 

BACK  OF  THE  the  subjacent  tendons  by  an  abundance  of  loose 

HAND  AND  connective  tissue,  in  which  are  large  veins,  and 

FINGERS,  branches  of  the  radial  and   ulnar   nerves.     The 

dorsal  branch  of  the  ulnar  nerve  passes  beneath  the  tendon  of 
the  flexor  carpi  ulnaris,  over  the  internal  lateral  ligament  of  the 
wrist,  and  divides  upon  the  back  of  the  hand  into  filaments, 
which  supply  both  sides  of  the  back  of  the  little  finger,  the  ring 
finger,  and  the  ulnar  side  of  the  middle  finger.  The  radial  nerve 
passes  obliquely  beneath  the  tendon  of  the  supinator  longus,  and 
subdivides  into  filaments,  which  supply  both  sides  of  the  back 
of  the  thumb  and  forefinger,  and  the  radial  side  of  the  middle 
finger.* 

The  radial  nerve  commonly  gives  off,  on  the  back  of  the  hand, 
a  branch  which  joins  the  nearest  branch  of  the  ulnar. 

FASCIA  ON  BACK         The  fascia  on  the  back  of  the  forearm  is  com- 
OF  FOREARM.  posed  of  fibres  interlacing  and  stronger  than  that 

upon  the  front  of  the  forearm.  It  is  attached  to  the  condyles  of 
the  humerus  and  to  the  olecranon,  and  is  strengthened  by  an  ex- 
pansion from  the  tendon  of  the  triceps.  Along  the  forearm  it  is 
attached  to  the  ridge  on  the  posterior  part  of  the  ulna.  Its  upper 
third  gives  origin  to  the  fibres  of  the  muscles  beneath  it,  and  divides 
them  by  septa,  to  which  their  fibres  are  also  attached. 

POSTERIOR  This  ligament  should  be  considered  as  a  part  of 

ANNULAR  LIGA-  the  fascia  of  the  forearm,  specially  strengthened 
MENT-  by  oblique  aponeurotic  fibres  on  the  back  of  the 

wrist,  to  confine  the  extensor  tendons.     These  fibres  are  attached 

*  The  relative  share  which  the  radial  and  ulnar  nerves  take  in  supplying  the 
fingers  varies.  Under  any  arrangement  the  thumb  and  each  finger  has  two  dorsal 
nerves,  one  on  either  side,  of  which  the  terminal  branches  reach  the  root  of  the  nail. 
They  supply  filaments  to  the  skin  on  the  back  of  the  finger,  and  have  frequent  com- 
munications with  the  palmar  digital  nerves.  In  some  instances,  one  or  more  of  the 
dorsal  nerves  do  not  extend  beyond  the  first  phalanx  ;  their  place  is  then  supplied  by 
ft  branch  from  the  palmar  nerve. 


DISSECTION    OP   THE   BACK    OF    THE    FOREARM.  327 

to  the  styloid  process  of  the  radius, .: and  thence  pass  obliquely 
inwards  to  the  inner  side  of  the  wrist,  where  they  are  connected 
with  the  pisiform  and  cuneiform  bones.  They  pass  below  the 
styloid  process  of  the  ulna,  to  which  they  are  in  no  way  attached, 
otherwise  the  rotation  of  the  radius  would  be  impeded.  - 

SEPARATE  From  the  deep  surface  of  the  posterior  annular 

SHEATHS  FOE  ligament,  processes  are  attached  to  the  ridges  on  the 

EXTENSOR  back  of  the  radius  so  as  to  form  six  ^distinct  -sheaths 

for  the  passage  of  the  extensor-tendons.  Commenc- 
ing from  the  radius,  the  first  sheath  contains  the  tendons  of  the 
extensor  ossis  metacarpi  and  the  extensor  primi  internodii  pollicis; 
the  second,  the  tendons  of  the  extensor  carpi  radialis  longior  and 
brevior ;  the  third,  the  tendon  of  the  extensor  secundi  internodii 
pollicis ;  the  fourth  the  tendons  of  the  indicator  and  the  extensor 
communis  digitorum ;  the  fifth,  the  tendon  of  the  extensor  minimi 
digiti ;  and  the  sixth,  the  tendon  of  the  extensor  carpi  ulnaris. 
All  the  sheaths  are  lined  by  synovial  membranes,  which  extend 
nearly  to  the  insertions  of  their  tendons.  Occasionally,  but 
not  often,  one  or  more  of  them  communicate  with  the;  wrist- 
joint. 

The  fascia  of  the  metaearpus  consists  of  a  thin  fibrous  layer, 
continued  from  the  posterior  annular  ligament.  It  separates  the 
extensor  tendons  from  the  subcutaneous  veins  and  nerves,  and  is 
attached  to  the  radial  side  of  the  second  metacarpal  bone,  and  the 
ulnar  side  of  the  fifth.. 

The  fascia  must  be  removed  from  the  muscles, 
DISSECTION.  •  >!-•••         ±1  i        fi  -,  •  i         • 

without  injuring  the  muscular  fibres  which  arise 

from  its  under  surface.  Preserve  the  posterior  annular  ligament. 
The  following  superficial  muscles  are  now  exposed,  and  should  be 
examined  in  the  order  in  which  they  are  placed,  proceeding  from 
the  radial  to  the  ulnar  side: — 1.  The  supinator  radii  longus 
SUPERFICIAL  (already  described,  p.  290).  2.  The  extensor  carpi 
MUSCLES  ON  THE  radialis  longior.  3.  The  extensor  carpi  radialis 
BACK  OF  THE  brevior.  4.  The  extensor  communis  digitorum. 

FOREARM.  5^  The  extensor  minimi  digiti.     6.  The  extensor 

carpi  ulnaris.     7.  The  anconeus. 


328  DISSECTION    OF    THE    BACK    OP   THE    FOREARM, 

A  little  below  the  middle  of  the  forearm,  the  extensors  of  the 
wrist  and  fingers  diverge  from  each  other,  leaving  an  interval,  in 
which  are  seen  the  three  extensors  of  the  thumb — namely,  the  ex- 
tensor ossis  metacarpi  pollicis,  the  extensor  primi  internodii  pollicis, 
and  the  extensor  secundi  internodii  pollicis.  The  two  former  cross 
the  radial  extensors  of  the  wrist,  and  pass  over  the  lower  third  of 
the  radius. 

Between  the  second  and  third  extensors  of  the  thumb,  we  ob- 
serve a  part  of  the  lower  end  of  the  radius,  which  is  not  covered 
either  by  muscle  or  tendon.  This  subcutaneous  portion  of  the 
bone  is  immediately  above  the  prominent  tubercle  in  the  middle 
of  its  lower  extremity,  and,  since  it  can  be  easily  felt  through  the 
skin,  it  presents  a  convenient  place  for  examination  in  doubtful 
cases  of  fracture. 

EXTENSOR  This  muscle  is  partly  covered  by  the  supinator 

CARPI  BADIALIS  radii  longus.  It  arises  from  the  lower  third  of 
LONGIOR.  {.jje  ridge  leading  to  the  external  condyle  of  the 

humerus,  and  from  the  intermuscular  septum.  It  descends  along 
the  outer  side  of  the  forearm,  and  terminates  about  the  middle,  in 
a  flat  tendon^  which  passes  beneath  the  extensor  ossis  metacarpi 
and  primi  internodii  pollicis,  traverses  a  groove  on  the  outer  and 
back  part  of  the  radius,  lined  by  a  synovial  membrane,  and  is 
inserted  into  the  radial  side  of  the  carpal  end  of  the  metacarpal 
bone  of  the  index  finger.  Previous  to  its  insertion,  the  tendon  is 
crossed  by  the  extensor  secundi  internodii  pollicis.  '  It  is  supplied 
by  a  branch  from  the  musculo-spiral  nerve. 

EXTENSOR  This  muscle  arises  from  the  external  condyle 

CARPI  RADIALIS  by  the  tendon  common  to  it  and  the  other  ex- 
BRETIOR.  tensors,  from  the  inter-muscular  septa,  and  from 

the  external  lateral  ligament  of  the  elbow-joint.  The  muscular 
fibres  terminate  near  the  middle  of  the  forearm,  upon  the  under 
surface  of  a  flat  tendon,  which  descends,  covered  by  that  of  the 
extensor  carpi  radralis  longior,  beneath  the  three  extensors  of  the 
thumb.  The  tendon  traverses  a  groove  on  the  back  of  the  radius, 
on  the  same  plane  with  that  of  the  long  radial  extensor,  but  lined 
by  a  separate  synovial  membrane,  and  is  inserted  into  the  radial 


DISSECTION    OF    THE    BACK    OF    THE    FOREARM.  329 

side  of  the  metacarpal  bone  of  the  middle  finger.  A  bursa  is 
generally  found  between  the  tendon  and  the  bone.  Its  nerve  comes 
from  the  posterior  interosseous. 

EXTENSOR  DIGI-  This  muscle  arises  from  the  common  tendon 
TOKUM  COMMUNIS.  attached  .  to  the  external  condy  le,  from  the  septa 
between  it  and  the  contiguous  muscles,  and  from  its  strong  fascial 
covering.  About  the  middle  of  the  forearm,  the  muscle  divides 
into  three  or  four  fleshy  slips,  terminating  in  as  many  flat  tendons, 
which  pass  beneath  the  posterior  annular  ligament,  through  a 
groove  on  the  back  of  the  radius  lined  by  synovial  membrane.  On 
the  back  of  the  hand  the  tendons  become  broader  and  flatter,  and 
diverge  from  each  other  towards  the  metacarpal  joints  of  the 
ringers,  where  they  become  thicker  and  narroAver,  and  give  off,  on 
each  side,  a  fibrous  expansion,  which  covers  the  sides  of  the  joint. 
Over  the  first  phalanx  of  the  finger,  each  tendon  again  spreads  out, 
receives  the  expanded  tendons  of  the  lumbricales  and  interossei 
muscles,  and  divides  at  the  second  phalanx  into  three  portions,  of 
which  the  middle  is  inserted  into  the  upper  end  of  the  second 
phalanx ;  the  two  lateral,  reuniting  over  the  lower  end  of  the 
second  phalanx,  are  inserted  into  the  upper  end  of  the  third.*  Its 
nerve  comes  from  the  posterior  interosseous. 

The  oblique  aponeurotic  slips  which  connect  the  tendons  on 
the  back  of  the  hand  are  subject  to  great  variety.  The  tendon 
of  the  index  finger  is  commonly  free  ;  it  is  situated  on  the  radial 
side  of  the  proper  indicator  tendon,  and  becomes  united  with  it  at 
the  metacarpal  joint. 

The  tendon  of  the  middle  finger  usually  receives  a  slip  from 
that  of  the  ring.  The  tendon  of  the  ring  finger  generally  sends  a 
slip  to  the  tendons  on  either  side  of  it,  and,  in  some  cases,  entirely 
furnishes  the  tendon  of  the  little  finger.  Thus  the  ring  finger 
does  not  admit  of  independent  extension. 

*  The  extensor  tendons  are  inserted  into  the  periosteum  ;  but  the  flexor  tendons 
are  inserted  into  the  substance  of  the  bone.  This  accounts  for  the  facility  with  which 
the  former  will  tear  off  the  bones  in  cases  of  necrosis,  while  the  latter  will  adhere  so 
tightly  as  to  require  cutting  before  the  phalanx  can  be  removed.  It  probably  also 
explains  the  great  liability  to  necrosis  which  is  so  frequently  observed  in  cases  of 
thecal  abscess. 


330      DISSECTION  OF  THE  BACK  OP  THE  FOREARM. 

The  muscle  is  not  only  a  general  extensor  of  the  fingers,  but 
can  extend  some  of  the  phalanges  independently  of  the  rest :  e.g. 
it  can  extend  the  first  phalanges  while  the  second  and  third  are 
flexed;  or  it  can  extend  the  second  and  third  phalanges  during 
flexion  of  the  first. 

EXTENSOR  This  long  slender  muscle,  situated  on  the  inner 

MINIMI  DIGITI  OB  side  of  the  common  extensor,  arises  from  the 
AURICUIARIS.  common  tendon  from  the  external  condyle,  and 

from  the  septa  between  it  and  the  contiguous  muscles.  Its  slender 
tendon  runs  separately  beneath  the  annular  ligament  immediately 
behind  the  joint  between  the  radius  and  ulna,  in  a  special  sheath 
lined  by  sy  no  vial  membrane.-  At-the-first  joint  of  the  little  finger, 
the  tendon  is  joined  by  that  of  the  common  extensor,  and  both 
expand  upon  the  first  and  second  phalanges,  terminating  in  the 
same  manner  as  the  extensor  tendons  of  the  other  fingers.  Its 
nerve  comes  from  the  posterior  interosseous. 

EXTENSOR  This  muscle  arises  from  the  common  tendon 

CARPI  ULNARIS.  from  the  external  condyle,  from  the  septum  be- 
tween it  and  the  extensor  minimi  digiti,  and  from  the  aponeurosis 
of  the  forearm.  The  fibres  terminate  upon  a  strong  broad  tendon, 
which  traverses  a  distinct  groove  on  the  back  of  the  ulna,  close  to 
the  styloid  process,  and  is  inserted  into  the  posterior  aspect  of  the 
carpal  end  of  the  metacarpal  bone  of  the  little  finger.  Below  the 
styloid  process  of  the  ulna,  the  tendon  passes  beneath  the  posterior 
annular  ligament,  over  the  back  of  the  wrist,  and  is  confined  in  a 
very  strong  fibrous  canal,  which  is  attached  to  the  back  of  the 
cuneiform,  pisiform,  and  unciform  bones,  and  is  lined  by  a  continu- 
ation from  the  synovia!  membrane  in  the  groove  of  the  ulna.  The 
action  of  this  muscle  is  to  extend  the  hand,  and  incline  it  towards 
the  ulnar  side.  It  is  supplied  by  the  posterior  interosseous  nerve. 

In  pronation  of  the  forearm,  the  lower  end  of  the  ulna  projects 
between  the  tendons  of  the  extensor  carpi  ulnaris  and  the  extensor 
minimi  digiti.  A  subcutaneous  bursa  is  sometimes  found  above 
the  bone  in  this  situation. 

This  small  triangular  muscle  is  situated  at  the 
outer  and  back  part  of  the  elbow.     It  is  covered 


DISSECTION    OF    THE    BACK    OF    THE    FOREARM.  331 

by  a  strong  layer  of  fascia,  derived  from  the  tendon  of  the  triceps, 
and  appears  like  a  continuation  of  that  muscle.  It  arises  by 
a  tendon  from  the  posterior  part'  of  the  external  condyle  of  the 
humerus,  and  is  inserted  into  the  triangular  surface  on  the  upper 
fourth  of  the  outer  part  of  the  ulna.  Part  of  the  under  surface  of 
the  muscle  is  in  contact  with  the  capsule  of  the  elbow-joint.  Its 
action  is  to  assist  in  extending  the  forearm.  Its- nerve  comes  from 
the  musculo-spiral. 

To  expose  the  deep  layer   of  muscles,  detach 
DISSECTION.  ,,  ,  ,  ,   ,        ,, 

from   the  external    condyle    the    extensor   carpi 

radialis  brevior,  the  extensor  communis  digitorum,  the  extensor 
minimi  digiti,  and  the  extensor  carpi  ulnaris ;  and,  after  noticing 
the  vessels  and  nerves  which  enter  their  under  surface,  turn  them 
down.  The  deep-seated  muscles,  with  the  posterior  interosseous 
artery  and  nerve,  must  be  dissected.  The  muscles  exposed  are : 

1.  The  extensor,  ossis  metacarpi  pollicis.      2.  EX- 
DEEP-SEATED  .  11.  r 
MUSCLES  ON  THE       tensor  primi  internodii  pollicis.     3.  Extensor  se- 

BACX  OF  THE  cundi  internodii  pollicis.  4.  Extensor  indicis  or 

FOREARM.  indicator.  5.  The  supinator  radii  brevis.  They 

are  all  supplied  by  branches  fronv  the  posterior  interosseous  nerve. 

EXTENSOR  This  muscle  arises  from  the  posterior  surface  of 

Ossis  METACARPI  the  ulna  below  the  supinator  brevis,  from  the 
POLLICIS.  posterior  surface  of  the  radius,  and  from  the  inter- 

osseous membrane.  The  muscle  crosses  the  radial  extensors  of  the 
wrist  about  three  inches  above  the  carpus,  and  terminates  in  a 
tendon,  which  passes  along  a  common  groove  with  the  extensor 
primi  internodii  pollicis,  lined  by  synovial  membrane,  on  the  outer 
part  of  the  lower  end  of  the  radius,  and  is  inserted  into  the  base 
of  the  metacarpal  bone  of  the  thumb,  and  frequently  also  by  a 
tendinous  slip  into  the  trapezium. 

EXTENSOR  This  small  muscle  arises  from  the  posterior 

PBIMI  INTERNODII  surface  of  the  radius,  below  the  preceding,  and 
POLLICIS.  from  the  interosseous  membrane.  It  descends 

obliquely  in  company  with  the  preceding  muscle,  turns  over  the 
radial  extensors  of  the  wrist,  and  terminates  upon  a  tendon  which 
passes  beneath  the  annular  ligament,  through  the  groove  on  the 


332      DISSECTION  OF  THE  BACK  OP  THE  FOREAKM. 

outer  part  of  the  radius,  and  is  inserted  into  the  radial  side  of  the 
base  of  the  first  phalanx  of  the  thumb. 

EXTENSOR  This   muscle  arises  from  the  posterior   surface 

SECUNDI  INTER-  of  the  ulna,  below  the  last  muscle,  and  from  the 
NODII  POLLICIS.  interosseons  membrane.  The  tendon  receives 
fleshy  fibres  as  low  as  the  wrist,  passes  beneath  the  annular  liga- 
ment, in  a  distinct  groove  on  the  back  of  the  radius,  crosses  the 
tendons  of  the  radial  extensors  of  the  wrist,  proceeds  over  the 
metacarpal  bone  and  the  first  phalanx  of  the  thumb,  and  is  in- 
serted into  the  base  of  the  last  phalanx. 

The  tendons  of  the  three  extensors  of  the  thumb  may  be  easily 
distinguished  in  one's  own  hand.  The  extensor  ossis  metacarpi, 
and  primi  internodii  pollicis,  cross  obliquely  over  the  radial  artery 
where  it  lies  on  the  external  lateral  ligament  of  the  carpus ;  the 
extensor  secundi  internodii  pollicis  crosses  the  artery  just  before 
it  sinks  into  the  palm,  between  the  first  and  second  metacarpal 
bones,  and  is  a  good  guide  to  the  vessel.  The  action  of  the  three 
extensors  of  the  thumb  is  implied  by  'their  names. 

EXTENSOR  This  muscle  arises  from  the  posterior  surface 

INDICTS  OR  INDI-  of  the  ulna,  below  the  extensor  secundi  inter- 
CATOR.  nodii  pollicis.  The  tendon  passes  beneath  the 

posterior  annular  ligament,  in  the  same  groove,  on  the  back  of 
the  radius,  with  the  tendons  of  the  extensor  digitorum  communis. 
It  then  proceeds  over  the  back  of  the  hand  to  the  first  phalanx  of 
the  index  finger,  where  it  is  united  to  the  inner  border  of  the  com- 
mon extensor  tendon.  By  the  action  of  this  muscle  the  index 
finger  can  be  extended  independently  of  the  others. 

Eeflect  the  extensor  carpi  radialis  brevior  and 
the  anconeus  from  their  origins,  to  expose  the  fol- 
lowing muscle. 

SUPINATOR  This  muscle  embraces  the  upper  third  of  the 

RADII  BRBVIS.  radius.  It  arises  from  the  external  lateral  liga- 
ment of  the  elbow-joint,  from  the  annular  ligament  surrounding 
the  head  of  the  radius,  from  an  oblique  ridge  on  the  outer  surface 
of  the  ulna  below  the  insertion  of  the  anconeus,  and  by  fleshy  fibres 
from  the  triangular  excavation  below  the  lesser  sigmoid  notch  of 


DISSECTION    OF    THE    BACK    OP    THE    FOEEAEM.  333 

the  ulna.  The  muscular  fibres  turn  over  the  neck  and  upper  part 
of  the  shaft  of  the  radius,  and  are  inserted  into  the  upper  third  of 
this  bone,  as  far  forwards  as  the  ridge  leading  from  the  tubercle 
to  the  insertion  of  the  pronator  teres.  The  muscle  is  traversed 
obliquely  by  the  posterior  interosseous  nerve,  which  sends  a  branch 
to  it,  and  its  upper  part  is  in  contact  with  the  capsule  of  the 
elbow-joint.  It  is  a  powerful  supinator  of  the  forearm,  some  of  its 
fibres  acting  at  nearly  a  right  angle  to  the  axis  of  the  radius. 

POSTERIOE  This  artery  comes  from  the  ulnar  by  a  common 

INTEROSSEOUS  trunk  with  the  anterior  interosseous  (p.  296),  and 

ARTERY.  supplies  the  muscles  on  the  back  of  the  forearm. 

It  passes  between  the  oblique  ligament  and  the  interosseous  mem- 
brane, and  appears,  at  the  back,  between  the  supinator  radii  brevis 
and  the  extensor  ossis  metacarpi  pollicis.  After  supplying  branches 
to  all  the  muscles  in  this  situation,  the  artery  descends,  much 
diminished  in  size,  between  the  superficial  and  deep  layer  of 
muscles  to  the  wrist,  where  it  inosculates  with  the  carpal  branches 
of  the  anterior  interosseous,  and  the  posterior  carpal  branches  of 
the  radial  and  ulnar  arteries. 

The  largest  branch  of  this  artery  is  the  interosseous  recurrent.  It 
ascends  beneath  the  anconeus  to  the  space  between  the  external  condyle 
and  the  olecranon,  where  it  inosculates  with  the  branch  of  the  superior 
profunda,  which  descends  in  the  substance  of  the  triceps,  and  with  the 
posterior  ulnar  recurrent  artery. 

In  the  lower  part  of  the  back  of  the  forearm,  a  branch  of  the 
anterior  interosseous  artery  is  seen  passing  through  the  interosseous 
membrane  to  reach  the  back  of  the  wrist. 

POSTERIOR  The  nerve  which  supplies  the  muscles  on  the 

INTEROSSEOUS  back  of  the  forearm,  is  the  posterior  interosseous, 

NERVE,  one  of  the   divisions  of  the   musculo-spiral.     It 

passes  obliquely  through  the  supinator  radii  brevis,  and  descends 
between  the  superficial  and  deep  layer  of  muscles  on  the  back  of 
the  forearm,  sending  to  each  a  filament,  generally  in  company  with 
a  branch  of  the  posterior  interosseous  artery.  It  sends  a  branch  to 
the  extensor  carpi  radialis  brevior,  and  supplies  the  supinator  brevis 
in  passing  through  its  substance.  The  supinator  radii  longus  and 


334 


DISSECTION    OF   THE    BACK   OF   THE    FOREARM. 


the  extensor  carpi  radialis  longior  are  supplied  by  distinct  branches 
from  the  musculo-spiral. 

The  continuation  of  the  posterior  interosseous  nerve  descends 
beneath  the  extensor  secundi  internodii  pollicis  and  the  tendons  of 
the  extensor  digitorum  communis  to  the  back  of  the  wrist.  Behind 

FIG.  61. 


1.  The  superior  profunda. 

2.  The  anastomotica  magna. 

3.  The  posterior  ulnar  recur- 

rent. 


4.  The  posterior )  5^  ascending 

interosseous  f^d  descend- 
I  ing  branches. 

5.  The  termination  of  the  an- 

terior interosseons. 

6.  The  posterior  carpal  arch. 


DIAGRAM    SHOWING    THE    ANASTOMOSES    OF   ARTERIES    AT    THE    BACK    OF    THE    ELBOW 
AND    WRIST    JOINTS. 

the  common  extensor  tendons  the  nerve  forms  a  gangliform  enlarge- 
ment from  which  filaments  are  sent  to  the  carpal  and  metacarpal 
joints. 

DISSECTION.  ^ie  radial  artery  is  continued  over  the  external 

RADIAL  ARTERY     lateral  ligament  of  the  carpus,  beneath  the  extensor 

ON  THE  BACK  OF       tendons  of  the  thumb,  to  the  proximal  part  of  the 

interval  between  the  first  and  second  metacarpal 


DISSECTION    OF    THE    BACK    OF    THE    FOEEAEM.  335 

bones,  where  it  dips  down  between  the  two  origins  of  the  abductor 
indicis,  and,  entering  the  palm,  forms  the  deep  palmar  arch.  In 
this  part  of  its  course  it  is  crossed  by  filaments  of  the  radial  nerve ; 
observe,  also,  that  the  tendon  of  the  extensor  secundi  internodii 
pollicis  passes  over  it  immediately  before  it  sinks  into  the  palm. 
It  supplies  the  following  small  branches  *to  the  back  of  the 
hand : — 

a.  Posterior  carpal  artery. — This  branch    passes  across  the  carpal 
bones,  beneath  the  extensor  tendons.     It  inosculates  with  the  termina- 
tion of  the  anterior  interosseous  artery,  and  forms  an  arch  beneath  the 
extensor  tendons,  with  a  corresponding  branch  from  the  ulnar  artery. 
The  carpal  artery  sends  off  small  branches,  called  the  dorsalinterosseous, 
which  descend  along  the  third  and  fourth  interosseous  spaces  from  the 
arch  just  mentioned,  beneath  the  extensor  tendons,  and  inosculate  near 
the  carpal  ends  of  the  metacarpal  bones  with  the  perforating  branches 
from  the  deep  palmar  arch. 

b.  The  first  dorsal  interosseous  artery  is  generally  larger  than  the 
others.     It  passes  towards  the  second  interosseous  space  to  the  cleft  be- 
tween the  index  and  middle  fingers,  communicating  here  with  a  perfora- 
ting branch  of  the  deep  palmar  arch,  and  terminates  in  small  branches, 
some  of  which  proceed  along  the  back  of  the  fingers,   others  inosculate 
with  the  palmar  digital  arteries. 

c.  The  dorsal  artery  of  the  index-finger,  a  branch  of  variable  size, 
passes  over  the  first  interosseous  muscle  to  the  radial  side  of  the  back  of 
the  index  finger. 

d.  The  dorsal  arteries  of  the  thumb  are  two  small  branches  which 
arise  from  the  radial  opposite  the  head  of  the  first  metacarpal  bone,  and 
run  along  the  back  of  the  thumb,  one  on  either  side.     They  are  often 
absent. 

These  dorsal  interosseous  arteries  supply  the  extensor  tendons  and 
their  sheaths,  the  interosseous  muscles,  and  the  skin  on  the  back  of  the 
hand,  and  the  first  phalanges  of  the  fingers. 

Remove  the  tendons  from  the  back,  and  from 

the  palm,  of  the  hand :  observe  the  deep  palmar 

fascia  which  covers  the  interosseous  muscles.     It  is  attached  to 

the  ridges  of  the  metacarpal  bones,  forms  a  distinct  sheath  for 

each   interosseous   muscle,  and  is  continuous  inferiorly  with  the 


336 


INTEKOSSEOUS    MUSCLES. 


transverse  metacarpal  ligament.  On  the  back  of  the  hand  the 
interosseous  muscles  are  covered  by  a  thin  fascia,  which  is  attached 
to  the  adjacent  borders  of  the  metacarpal  bones. 

TRANSVERSE  This  consists  of  strong  bands  of  ligamentous 

METACARPAL  fibres,  which  pass  transversely  between  the  distal 

LIGAMENT.  extremities  of  the  metacarpal  bones.    These  bands 

are  intimately  united  to  the  fibre-cartilaginous  ligament  of  the 
metacarpal  joints,  and  are  of  sufficient  length  to  admit  of  a  certain 
degree  of  movement'  between  the  ends  of  the  metacarpal  bones. 


FIG.  62. 


FIG,  63. 


DIAGRAM  OF  THE  FOUR  DORSAL  IN- 
TEROSSEI,  DRAWING  FROM  THE 
MIDDLE  LINE. 


DIAGRAM  OF  THE  THREE  PALMAR  1NTEB- 
OSSEI.  AND  THE  ADDUCTOR  POLLICIS, 
DRAWING?  TOWARDS  THE  MIDDLE  LINE. 


DISSECTION. 


Remove  the  fascia  which  covers  the  interosseous 
muscles,  and  separate  the  metacarpal  bones  by 
dividing  the  transverse  metacarpal  ligament.  A  bursa  is  fre- 
quently developed  between  their  digital  extremities. 

INTEROSSEOUS  These  muscle&,  so  named  from  their  position, 

MUSCLES.  extend  from  the  sides  of  the  metacarpal  bones  to 

the  bases  of  the  first  phalanges  and  the  extensor  tendons  of  the 
fingers.  In  each  interosseous  space  (except  the  first,  in  which 
there  is  only  an  abductor)  there  are  two  muscles,  one  of  which 


INTEROSSEOUS   MUSCLES.  337 

is  an  abductor,  the  other  an  adductor,  of  a  finger.  Thus  there 
are  seven  in  all ;  four  of  which,  situated  on  the  back  of  the  hand, 
are  called  dorsal ;  the  remainder,  seen  only  in  the  palm,  are  called 
palmar.*  They  are  all  supplied  by  the  ulnar  nerve. 

DOKSAL  Each  dorsal  interosseous  muscle  arises  from  the 

INTEBOSSEI.  opposite  sides  of  two  contiguous  metacarpal  bones 

(fig.  62).  From  this  double  origin  the  fibres  converge  to  a  ten- 
don, which  passes  between  the  metacarpal  joints  of  the  finger,  and 
is  inserted  into  the  side  of  the  base  of  the  first  phalanx,  and  by  a 
broad  expansion  into  the  extensor  tendon  on  the  back  of  the  same 
finger. 

The  first  dorsal  interosseous  muscle  (abductor  indicia]  is  larger 
than  the  others,  and  occupies  the  interval  between  the  thumb  and 
fore-finger.  It  arises  from  the  proximal  half  of  the  ulnar  side  of 
the  first  metacarpal  bone,  and  from  the  entire  length  of  the  radial 
side  of  the  second  :  between  the  two  origins,  the  radial  artery  passes 
into  the  palm.  Its  fibres  converge  on  either  side  to  a  tendon, 
which  is  inserted  into  the  radial  side  of  the  first  phalanx  of  the 
index  finger  and  its  extensor  tendon. 

The  second  dorsal  interosseous  muscle  occupies  the  second 
metacarpal  space.  It  is  inserted  into  the  radial  side  of  the  first 
phalanx  of  the  middle  finger  and  its  extensor  tendon. 

The  third  and  fourth,  occupying  the  corresponding  metacarpal 
spaces,  are  inserted,  the  one  into  the  ulnar  side  of  the  middle,  the 
other  into  the  ulnar  side  of  the  ring  finger. 

If  a  line  be  drawn  longitudinally  through  the  middle  finger, 
as  represented  by  the  dotted  line  in  fig.  62,  we  find  that  all  the 
dorsal  interosseous  muscles  are  abductors  from  that  line;  conse- 
quently, they  separate  the  fingers  from  each  other. 

PALMAR  INTER-          It  requires  a  careful  examination  to  distinguish 
OSSEOUS.  this  set  of  muscles,  because  the  dorsal  muscles 

protrude  with  them  into  the  palm.  They  are  smaller  than  the 
dorsal,  and  each  arises  from  the  lateral  surface  of  only  one  meta- 
carpal bone — that,  namely,  connected  with  the  finger  into  which 

*  If  we  consider  the  adductor  pollicis  as  a  palmar  interosseous  muscle,  there  would 
be  four  palmar  and  four  dorsal — all  supplied  by  the  ulnar  nerve. 

Z 


338  STEKSO-CLAVICULAR   JOINT. 

the  muscle  is  inserted  (fig.  63).  They  terminate  in  small  tendons, 
which  pass  between  the  metacarpal  joints  of  the  fingers,  and  are 
inserted,  like  those  of  the  dorsal  muscles,  into  the  sides  of  the  first 
phalanges  and  the  extensor  tendons  on  the  back  of  the  fingers. 

The  first  palmar  interosseous  muscle  arises  from  the  ulnar  side 
of  the  second  metacarpal  bone,  and  is  inserted  into  the  ulnar  side 
of  the  index  finger.  The  second  and  third  arise,  the  one  from  the 
radial  side  of  the  fourth,  the  other  from  the  radial  side  of  the  fifth 
metacarpal  bone,  and  are  inserted  into  the  same  sides  of  the  ring 
and  little  fingers. 

The  palmar  interosseous  muscles  are  all  adductors  to  a  line 
drawn  through  the  middle  finger  (fig.  63).  They  are,  therefore, 
the  opponents  of  the  dorsal  interosseous,  and  move  the  fingers 
towards  each  other. 

The  palmar  and  dorsal  interossei  are  supplied  by  filaments 
from  the  deep  branch  of  the  ulnar  nerve. 


DISSECTION    OF   THE  LIGAMENTS. 

STBKNO-CLAVI-  The  inner  en(l  of  the  clavicle  articulates  with 

CULAK  JOINT.  the  comparatively  small  and  shallow  excavation 

on  the  upper  and  outer  part  of  the  sternum.  The  security  of  the 
joint  depends  upon  the  great  strength  of  its  ligaments.  There  are 
two  synovial  membranes,  and  an  intervening  fibro-cartilage. 

The  anterior  sterno-clavicular  ligament  (fig.  64)  consists  of  a 
strong  broad  band  of  ligamentous  fibres,  which  pass  obliquely 
downwards  and  inwards  over  the  front  of  the  joint,  from  the  inner 
end  of  the  clavicle  to  the  anterior  surface  of  the  sternum. 

The  posterior  sterno-clavicular  ligament  extends  over  the 
back  of  the  joint,  from  the  back  of  the  clavicle  to  the  back  of  the 
sternum  in  a  similar  manner  to  the  anterior. 

The  inter-clavicular  ligament  connects  the  clavicles  directly. 
It  extends  transversely  above  the  notch  of  the  sternum,  and  has  a 
broad  attachment  to  the  upper  border  of  each  clavicle.  Between 


STERNO-CLAV1CULAR   JOINT. 


339 


the  clavicles  it  is  more  or  less  attached  to  the  sternum,  so  that  it 
forms  a  curve  with  the  concavity  upwards. 

The  three  ligaments  just  described  are  so  closely  connected 
that,  collectively,  they  form  for  the  joint  a  complete  fibrous 
capsule  of  such  strength  that  dislocation  of  it  is  rare. 

The  costo-clavicular  or  rhomboid  ligament  connects  the  cla- 
vicle to  the  cartilage  of  the  first  rib.  It  ascends  obliquely  out- 
wards and  backwards  from  the  cartilage  of  the  rib  to  a  rough  sur- 
face beneath  the  sternal  end  of  the  clavicle.  Its  use  is  to  limit 
the  elevation  of  the  clavicle.  There  is  such  constant  movement 
between  the  clavicle  and  the  cartilage  of  the  first  rib  that  a  well- 
marked  bursa  is  commonly  found  between  them. 

FIG.  64. 


DIAGRAM    OF   THE    STJ3JJNO-CLAYICTLAB    LIGAMENTS. 


1.  Inter-clavicular  ligament. 

2.  Anterior  sterno-clavicular  ligament. 


3.  Costo-clavicular  ligament. 

4.  Inter-articular  fibro-cartilage. 


Inter-articular  fibro-cartilage. — To  see  this,  cut  through  the 
rhomboid,  the  anterior  and  posterior  ligaments  of  the  joint,  and 
raise  the  clavicle.  It  is  nearly  circular  in  form,  and  thicker  at 
the  circumference  than  the  centre,  in  which  there  is  sometimes  a 
perforation.  Inferiorly,  it  is  attached  to  the  cartilage  of  the  first 
rib,  close  to  the  sternum ;  superiorly,  to  the  upper  part  of  the 
clavicle  and  the  inter-clavicular  ligament.  Its  circumference  is 
inseparably  connected  with  the  anterior  and  posterior  ligaments. 

The  joint  is  provided  with  two  synovial  membranes :  one 
between  the  articular  surface  of  the  sternum  and  the  inner  surface 

z  2 


340  SCAPULO-CLAVICULAE   JOINT, 

of  the  fibro-cartilage ;  the  other  between  the  articular  surface  of 
the  clavicle  and  the  outer  surface  of  the  fibro-cartilage. 

This  inter-articular  fibro-cartilage  is  a  structure  highly  elastic, 
without  admitting  of  any  stretching.  It  equalises  pressure,  breaks 
shocks,  and  also  acts  as  a  ligament,  tending  to  prevent  the  clavicle 
from  being  driven  inwards  towards  the  mesial  line. 

Observe  the  relative  form  of  the  cartilaginous  surfaces  of  the 
bones :  that  of  the  sternum  is  slightly  concave  in  the  transverse, 
and  convex  in  the  antero-posterior  direction  ;  that  of  the  clavicle 
is  the  reverse. 

The  form  of  the  articular  surfaces  and  the  ligaments  of  a  joint 
being  known,  it  is  easy  to  understand  the  movements  of  which  it 
is  capable.  The  clavicle  can  be  moved  upon  the  sternum  in  a 
direction  either  vertical  or  horizontal :  thus  it  admits  of  circum- 
duction.  These  movements,  though  limited  at  the  sternum,  are 
considerable  at  the  apex  of  the  shoulder. 

SCAPULO-  The  outer  end  of  the  clavicle  articulates  with 

CLAVICULAR  the  acromion,  and  is  connected  by  strong  liga- 

JomT-  ments  to  the  coracoid  process  of  the  scapula. 

The  clavicle  and  the  acromion  articulate  with  each  other  by 
two  flat  oval  cartilaginous  surfaces,  of  which  the  planes  slant  in- 
wards, and  the  longer  diameters  are  in  the  antero-posterior 
direction. 

The  superior  ligament,  a  broad  band  of  ligamentous  fibres, 
strengthened  by  the  aponeurosis  of  the  trapezius,  extends  from  the 
upper  surface  of  the  acromion  to  the  upper  surface  of  the  clavicle. 

The  inferior  ligament,  of  less  strength,  extends  along  the 
under  surface  of  the  joint  from  bone  to  bone. 

An  inter-articular  fibro-cartilage  is  sometimes  found  in  this 
joint :  but  it  is  incomplete,  and  seldom  extends  lower  than  the 
upper  half.  There  is  only  one  synovial  membrane. 

Coraco-clavicular  ligament.-  -The  clavicle  is  connected  to  the 
coracoid  process  of  the  scapula  by  two  strong  ligaments — the 
conoid  and  trapezoid,  which,  being  continuous  with  each  other, 
should  be  considered  as  one.  The  trapezoid  ligament  is  the  more 


SHOULDER   JOINT. 


341 


anterior  and  external.  It  arises  from  the  back  part  of  the  coracoid 
process,  and  ascends  obliquely  backwards  and  outwards  to  the 
clavicle,  near  its  outer  end.  The  conoid  ligament  is  fixed  at  its 
apex  to  the  root  of  the  coracoid  process,  ascends  nearly  vertically, 
and  is  attached  by  its  base  to  the  clavicle.  When  the  clavicle  is 
fractured  in  the  line  of  the  attachment  of  the  coraco-clavicular 
ligament,  there  is  little  or  no  displacement  of  the  fractured  ends, 
these  being  kept  in  place  by  the  ligament. 

LIGAMENTS  OF  These  are   two :    the  transverse  ligament,  at- 

THE  SCAPULA.  tached  to  the  margins  of  the  supra-scapular  notch ; 

and  the  coraco-acromial  or  triangular  ligament,  attached  by  its 


\  portions  of 

1.  Trapezoid  [the  coraco- 

2.  Conoid      |  clavicular 

'  ligament. 

3.  Supra-scapular  or  trans- 

verse ligament. 

4.  Coraco-acromial    liga- 

meiit. 


-—         5.  Tendon  of  biceps. 

6.  Capsular   ligament    of 

the  shoulder-joint. 
'  7.  Coraco-humeral     liga- 
ment. 

8.  Foramen  in  the  cap- 
sulnr  ligament  for  the 
subscapularis  tendon. 


ANTERIOR   TIEW   OF    THE    SCAPULO-CLAVICULAR    LIGAMENTS,    AND   OF   THB 
SHOULDER-JOINT. 

apex  to  the  acromion,  and  by  its  base  to  the  outer  border  of  the 
coracoid  process.  It  is  separated  from  the  upper  part  of  the 
capsule  of  the  shoulder-joint  by  a  large  bursa. 

SHOULDER-  The  articular  surface  of  the  head  of  the  humerus, 

JOINT-  forming  rather  more  than  one-third  of  a  sphere, 

moves  upon  the  shallow  glenoid  cavity  of  the  scapula,  which  is 
of  an  oval  form,  with  the  broader  end  downwards,  and  the  long 
diameter  nearly  vertical.  The  security  of  the  joint  depends,  not 
upon  any  mechanical  contrivance  of  the  bones,  but  upon  the  great 
strength  and  number  of  the  tendons  which  surround  and  are  in 
timately  connected  with  it. 


342  SHOULDER   JOINT. 

To  admit  the  free  motion  of  the  head  of  the  humerus  upon  the 
glenoid  cavity,  it  is  requisite  that  the  capsular  ligament  of  the 
joint  be  loose  and  capacious.  Accordingly,  the  head  of  the  bone, 
when  detached  from  its  muscular  connections,  may  be  separated 
from  the  glenoid  cavity  to  the  extent  of  an  inch,  or  more,  without 
laceration  of  the  capsule.  This  explains  the  elongation  of  the  arm 
observed  in  some  cases  in  which  effusion  takes  place  into  the  j  oint ; 
also  in  cases  of  paralysis  of  the  deltoid. 

The  capsular  ligament  is  attached  above,  round  the  circum- 
ference of  the  glenoid  cavity ;  below,  round  the  anatomical  neck 
of  the  humerus.  It  is  strongest  on  its  upper  aspect,  weakest  and 
longest  on  its  lower.  It  is  strengthened  on  its  upper  and  pos- 
terior part  by  the  tendons  of  the  supra-spinatus,  infra-spinatus, 
and  teres  minor ;  its  inner  part  is  strengthened  by  the  broad 
tendon  of  the  subscapularis,  its  lower  part  by  the  long  head  of  the 
triceps.  t 

Thus  the  circumference  of  the  capsule  is  surrounded  by  tendons 
on  every  side,  Excepting  a  small  space  towards  the  axilla.  If  the 
humerus  be  raised,  it  will  be  found  that  the  head  of  the  bone  rests 
upon  this  unprotected  portion  of  the  capsule,  between  the  tendons 
of  the  subscapularis  and  the  long  head  of  the  triceps  :  through  this 
part  of  the  capsule  the  head  of  the  bone  is  first  protruded  in  dis- 
locations into  the  axilla. 

At  the  upper  and  inner  side  of  the  joint,  a  small  opening 
(foramen  ovale)  is  observable  in  the  capsular  ligament,  through 
which  the  tendon  of  the  subscapularis  passes,  and  comes  in  contact 
with  the  synovial  membrane. 

The  upper  surface  of  the  capsule  is  strengthened  by  a  strong 
band  of  ligamentous  fibres,  called  the  coraco-humeral  or  accessory 
ligament.  It  is  attached  to  the  root  of  the  coracoid  process, 
expands  over  the  upper  surface  of  the  capsule,  with  which  it  is 
inseparably  united,  and  is  fixed  into  the  greater  tuberosity  of  the 
humerus. 

Open  the  capsule  to  see  the  tendon  of  the  long  head  of  the 
biceps.  It  enters  the  joint  through  the  groove  between  the  two 
tuberosities,  becomes  slightly  flattened,  and  passes  over  the  head 


ELBOW  JOINT.  343 

of  the  hone  to  be  attached  to  the  upper  border  of  the  glenoid 
cavity.  It  is  loose  and  movable  within  the  joint.  It  acts  like  a 
strap,  keeping  down  the  head  of  the  bone  when  the  arm  is  raised 
by  the  deltoid. 

The  tendon  of  the  biceps,  strictly  speaking,  does  not  perforate 
the  synovial  membrane  of  the  joint.  It  is  inclosed  in  a  tubular 
sheath,  which  is  reflected  over  it  at  its  attachment  to  the  glenoid 
cavity,  and  accompanies  it  for  two  inches  down  the  groove  of  the 
humerus.  During  the  earlier  part  of  foetal  life,  it  is  connected  to 
the  capsule  by  a  fold  of  synovial  membrane,  which  subsequently 
disappears. 

The  margin  of  the  glenoid  cavity  of  the  scapula  is  surrounded 
by  a  fibrous  band  of  considerable  thickness,  called  the  glenoid 
ligament.  This  not  only  enlarges,  but  deepens  the  cavity. 
Superiorly,  it  is  continuous  on  either  side  with  the  tendon  of  the 
biceps  ;  inferiorly,  with  the  tendon  of  the  triceps  :  in  the  rest  of 
its  circumference  it  is  attached  to  the  edge  of  the  cavity. 

The  cartilage  covering  the  head  of  the  humerus  is  thicker  at 
the  centre  than  at  the  circumference.  The  reverse  is  the  case  in 
the  glenoid  cavity. 

The  synovial  membrane  lining  the  under  surface  of  the  capsule 
is  reflected  around  the  tendon  of  the  biceps,  and  passes  with  it  in 
the  form  of  a  cul-de-sac  down  the  bicipital  groove.  On  the  inner 
side  of  the  joint  it  always  communicates  with  the  bursa  beneath 
the  tendon  of  the  subscapularis. 

The  shoulder-joint  has  a  more  extensive  range  of  motion  than 
any  other  joint  in  the  body ;  it  is  what  mechanics  call  a  universal 
joint.  It  is  capable  of  motion  forwards  and  backwards,  of  adduc- 
tion, abduction,  circumduction,  and  rotation. 

The  elbow-ioint  is  a  perfect  hinge.     The  larger 
ELBOW-JOINT. 

sigmoid  cavity  of  the   ulna   is    adapted  to   the 

trochlea  upon  the  lower  end  of  the  humerus,  admitting  only  of 
flexion  and  extension ;  while  the  shallow  excavation  upon  the  head 
of  the  radius  admits  not  only  of  flexion  and  extension,  but  of  rota- 
tion, upon  the  rounded  articular  eminence  (capitellum)  of  the 


344 


ELBOW   JOINT. 


humerus.  The  joint  is  secured  by  two  strong  lateral  ligaments. 
No  ligament  is  attached  to  the  head  of  the  radius,  otherwise  its 
rotatory  movement  would  be  impeded.  The  head  is  simply  sur- 
rounded by  a  ligamentous  collar,  called  the  annular  ligament, 
within  which  it  freely  rolls  in  pronation  and  supination  of  the 
hand. 

Internal  lateral  ligament. —  This  is  triangular,  and  is  divided 
into  two  portions,  an  anterior  and  a  posterior.  Its  anterior  part 
is  attached  to  the  front  of  the  internal  condyle  of  the  humerus  : 

FIG.  66. 


a.  External  lateral  liga- 
ment. 

6.  Orbicular  or  annular 
ligament. 


c.  Part   of  internal  la- 

teral ligament. 

d.  Radius,  removed  from 

the    annular   liga- 
ment. 


LIGAMENTS    OF    THE    ELBOW    JOINT. 


from  this  point  the  fibres  radiate,  and  are  inserted  along  the  inner 
margin  of  the  coronoid  process  of  the  ulna.  The  posterior  part  is 
also  triangular,  and  passes  from  the  back  part  of  the  internal  con- 
dyle to  the  inner  border  of  the  olecranon. 

A  band  of  fibres  extends  transversely  from  the  olecranon  to 
the  coronoid  process,  across  a  notch  observable  on  the  inner  side 
of  the  sigmoid  cavity :  through  this  notch  small  vessels  pass  into 
the  joint. 

External  lateral  ligament. — This  is  attached  to  the  external 
condyle  of  the  humerus,  and  is  in  intimate  connection  with  the 


RADIO-ULNAE,   JOINT.  345 

common  tendon  of  the  extensors.  The  fibres  spread  out  as  they 
descend,  and  are  interwoven  with  the  annular  ligament,  surround- 
ing the  head  of  the  radius. 

The  anterior  and  posterior  ligaments  of  the  elbow-joint  con- 
sist of  a  few  thin  ligamentous  fibres,  spread  over  the  capsule  of 
the  joint,  in  front  and  behind.  There  is  no  need  of  ligaments  to 
limit  flexion  and  extension  in  this  joint :  the  coronoid  process 
limits  the  one ;  the  olecranon  the  other. 

The  preceding  ligaments,  collectively,  form  a  continuous  cap- 
sule for  the  joint. 

SUPERIOR  The   orbicular    or   annular  ligament  of  the 

EADIO-ULNAR  radius  (fig.  66)  does  not  of  itself  make  a  ring. 

ABTICULATION.  j^g  en(jg  are  attached  to  the  anterior  and  posterior 
borders  of  the  lesser  sigmoid  cavity  of  the  ulna.  With  this  cavity 
it  forms  a  complete  collar,  which  encircles  the  head,  and  part  of 
the  neck,  of  the  radius.  The  lower  part  of  the  ring  is  narrower 
than  the  upper,  the  better  to  clasp  the  neck  of  the  radius,  and 
maintain  it  more  accurately  in  position.  The  external  lateral 
ligament  is  attached  to  its  outer  surface. 

Synovial  membrane  of  the  elbow-joint. — Open  the  joint  by  a 
transverse  incision  in  front,  and  observe  the  relative  adaptation  of 
the  cartilaginous  surfaces  of  the  bones.  The  synovial  membrane 
lines  the  interior  of  the  capsule,  and  forms  a  cul-de-sac  between 
the  head  of  the  radius  and  its  annular  ligament.  It  is  widest  and 
loosest  under  the  tendon  of  the  triceps.  Where  the  membrane  is 
reflected  from  the  bones  upon  the  ligaments,  there  is  more  or  less 
adipose  tissue,  particularly  in  the  fossse  on  the  front  and  back  part 
of  the  lower  end  of  the  humerus. 

INTEROSSEOUS  This  is  an  aponeurotic  septum,  stretched  be- 

LIGAMBNT  OR  tween  the  bones  of  the  forearm,  of  which  the  chief 

MEMBRANE.  purpose  is  to  afford  an  increase  of  surface  for  the 

attachment  of  muscles.  The  septum  is  deficient  above,  to  permit 
free  rotation  of  the  radius.  Its  fibres  extend  obliquely  downwards 
from  the  radius  to  the  ulna.  It  is  perforated  in  its  lower  third  by 
the  anterior  interosseous  vessels. 

The  name  of  round  or  oblique  ligament  is  given  to  a  thin 


346  RADIO-CARPAL    JOINT. 

band  of  fibres,  which  extends  obliquely  between  the  bones  of 
the  forearm  in  a  direction  contrary  to  those  of  the  interosseous 
membrane.  It  is  attached,  superiorly,  to  the  front  surface  of  the 
ulna,  near  the  outer  side  of  the  coronoid  process  ;  inferiorly,  to  the 
radius  immediately  below  the  tubercle.  Between  this  ligament 
and  the  upper  border  of  the  interosseous  membrane  is  a  triangular 
interval  through  which  the  posterior  interosseous  artery  passes  to 
the  back  of  the  forearm.  A  bursa  intervenes  between  the  oblique 
ligament  and  the  insertion  of  the  tendon  of  the  biceps.  The  use 
of  this  ligament  is  to  limit  supination  of  the  radius. 

BADIO-CARPAL  This  joint  is  formed  by  the  lower  end  of  the 

OR  WRIST-JOINT.  radius,  which  articulates  with  the  scaphoid  and 
semilunar  bones  of  the  carpus :  the  lower  end  of  the  ulna  is  ex- 
cluded from  the  joint  by  a  triangular  fibro- cartilage,  which  articu- 
lates with  a  small  portion  of  the  cuneiform  bone.  The  joint  is 
secured  by  an  anterior,  a  posterior,  and  two  lateral  ligaments. 

The  external  lateral  ligament  extends  from  the  styloid  process 
of  the  radius  to  the  scaphoid  bone,  to  the  anterior  annular  ligament, 
and  to  the  trapezium. 

The  internal  lateral  ligament  proceeds  from  the  extremity  of 
the  styloid  process  of  the  ulna  to  the  cuneiform  bone.  Some  of 
its  fibres  are  attached  to  the  pisiform  bone  and  the  anterior  annular 
ligament. 

The  anterior  ligament  consists  of  two  or  more  broad  bands  of 
ligamentous  fibres,  which  extend  from  the  lower  end  of  the  radius 
to  the  first  row  of  carpal  bones. 

The  posterior  ligament,  weaker  than  the  preceding,  proceeds 
from  the  posterior  surface  of  the  lower  end  of  the  radius,  and  is 
attached  to  the  posterior  surfaces  of  the  first  row  of  carpal  bones. 

The  synovial  membrane  lines  the  under  surface  of  the  trian- 
gular fibro-cartilage  at  the  end  of  the  ulna,  is  reflected  over  the 
several  ligaments  of  the  joint,  and  thence  upon  the  first  row  of 
the  carpal  bones. 

INFERIOR  ^e  inner  surface  of  the  lower  end  of  the  radius 

BADIO-TILNAR  presents  a   slight  concavity,  which  rotates  upon 

ABTICUI.ATION.         the  convex  head  of  the  ulna :  this  mechanism  is 


RADIO-CARPAL   JOINT. 


347 


essential  to  the  pronation  and  supination  of  the  hand.  These 
corresponding  surfaces  are  covered  with  a  thin  layer  of  cartilage, 
and  are  provided  with  a  very  loose  synovial  membrane.  The  joint 
is  strengthened  in  front  and  behind  by  thin  transverse  ligamentous 
fibres,  which  extend  from  the  anterior  and  posterior  borders  of  the 
sigmoid  cavity  of  the  radius  to  the  anterior  and  posterior  surfaces 
of  the  styloid  process  of  the  ulna.  But  the  principal  uniting  me- 
dium between  the  bones  is  the  following  strong  fibro-cartilage : — 

Fia.  67. 


1.  External  lateral  liga- 

ment 

2.  Internal  lateral  liga- 

ment. 

3.  Interarticular   fibro- 

cartilage     between 
radius  and  ulna. 


4.  Interosseous  liga- 

ments. 

5.  Lateral    ligaments 

of   the    intercar- 
pal  joint. 


DIAGRAM    OF    THE    LIGAMENTS    AND    SYNOVIAL    MEMBRANES    OF   THE   WRIST- JOINT. 

Fibro-cartilage  between  the  radius  and  ulna. — Saw  through 
the  bones  of  the  forearm,  and  separate  them  by  cutting  through 
the  interosseous  membrane,  and  opening  the  synovial  membrane 
of  the  joint  between  the  lower  ends.  Thus  a  good  view  is  ob- 
tained of  the  fibro-cartilage  which  connects  them  (fig.  67).  It  is 
triangular,  and  placed  transversely  at  the  lower  end  of  the  ulna, 
filling  up  the  interval  caused  by  the  greater  length  of  the  radius. 
Its  base  is  attached  to  the  lower  end  of  the  radius  ;  its  apex  to 


348  CARPAL   JOINTS. 

a  depression  at  the  root  of  the  styloid  process  of  the  ulna.  It  is 
thin  at  the  base  and  centre,  thicker  at  the  apex  and  sides.  Its 
upper  surface  is  in  contact  with  the  ulna,  and  covered  by  the 
synovial  membrane  of  the  radio-ulnar  joint ;  its  lower  surface, 
forming  a  part  of  the  wrist-joint,  corresponds  to  the  cuneiform 
bone.  Its  borders  are  connected  with  the  anterior  and  posterior 
ligaments  of  the  wrist.  In  some  instances  there  is  an  aperture  in 
the  centre. 

When,  from  accident  or  disease,  this  fibro-cartilage  gets  de- 
tached from  the  radius,  the  consequence  is  an  abnormal  projection 
of  the  lower  end  of  the  ulna. 

The  synovial  membrane  of  this  joint  is  distinct  from  that  of 
the  wrist,  except  in  the  case  of  a  perforation  through  the  fibro- 
cartilage.  On  account  of  its  great  looseness,  necessary  for  the  free 
rotation  of  the  radius,  it  is  called  membrana  sacciformis. 

The  bones  of  the  carpus  are  arranged  in  two 
CARPAL  JOINTS.  j       i  j       ,    j  j.  -L     J.T- 

rows,  an  upper  and  a  lower,  adapted  to  each  other, 

so  as  to  form  between  them  a  joint,  connected  by  anterior,  posterior, 
internal,  and  external  lateral  ligaments. 

The  bones  constituting  each  row  are  united  by  ligaments 
placed  on  their  palmar  and  dorsal  surfaces,  and  by  others  placed 
between  the  bones,  and  hence  called  interosseous.  Their  con- 
tiguous surfaces  (those  of  the  pisiform  and  cuneiform  excepted) 
are  covered  by  the  reflections  of  one  synovial  membrane. 

The  first  row  is  united  by  dorsal  and  palmar  transverse  liga- 
ments proceeding  from  the  scaphoid  to  the  semilunar  bone,  and 
from  the  semilunar  to  the  cuneiform  ;  also  by  interosseous  liga- 
ments, proceeding  from  the  semilunar  to  the  bones  on  either  side 
of  it  (fig,  67). 

The  pisiform  bone  is  articulated  to  the  palmar  surface  of  the 
cuneiform  bone,  to  which  it  is  united  by  a  fibrous  capsule.  In- 
feriorly  it  is  attached  by  two  strong  ligaments,  the  one  to  the 
unciform  bone,  the  other  to  the  carpal  end  of  the  fifth  metacarpal 
bone.  This  articulation  has  a  distinct  synovial  membrane. 

The  second  row  of  carpal  bones  is  connected  in  the  same  way 
as  the  upper.  The  dorsal  and  palmar  ligaments  pass  transversely 


CAEPAL   JOINTS.  349 

from  one  to  the  other.  There  are  usually  two  interosseous  liga- 
ments, one  on  either  side  of  the  os  magnum  ;  sometimes  there  is  a 
third,  between  the  trapezium  and  trapezoid  bones  ;  they  are  thicker 
and  stronger  than  those  of  the  upper  row,  and  unite  the  bones 
more  firmly  together. 

INTEBCABPAL  The  upper  row  of  carpal  bones  is  arranged  in  the 

JOINT.  form  of  an  arch,  so  as  to  receive  the  corresponding 

convex  surfaces  of  the  os  magnum  and  unciforme.  External  to 
the  os  magnum,  the  trapezium  and  trapezoid  bones  present  a 
slightly  concave  surface,  which  articulates  with  the  scaphoid.  In 
this  way  a  joint  admitting  of  flexion  and  extension  only  is  formed 
between  the  upper  and  lower  row.  It  is  secured  by  anterior, 
posterior,  and  two  lateral  ligaments. 

The  anterior  ligaments  consist  of  strong  ligamentous  fibres, 
which  pass  obliquely  from  the  bones  of  the  upper  to  those  of  the 
lower  row.  The  posterior  ligaments  consist  of  oblique  and  trans- 
verse fibres,  which  connect  the  dorsal  surfaces  of  the  bones  of  the 
upper  with  the  lower  row. 

The  lateral  ligaments  connect,  externally,  the  scaphoid  and 
trapezium  ;  internally,  the  cuneiform  and  imciform  bones. 

Divide  the  ligaments,  to  see  the  manner  in  which  the  carpal 
bones  articulate  with  each  other.  Their  surfaces  are  crusted  with 
cartilage,  and  have  a  common  synovial  membrane.  This  mem- 
brane extends,  superiorly,  between  the  three  bones  of  the  upper 
row,  so  as  to  form  two  culs-de-sac ;  inferiorly,  it  is  prolonged  into 
the  joint  between  the  carpal  and  the  second  and  third  metacarpal 
bones. 

JOINT  BETWEEN          ^ne  trapezium  presents  a  cartilaginous  surface, 
TBAPEZIUM  AND        convex  in  the  transverse,  and  concave  in  the  antero- 
THE  FIEST  META-      posterior  direction  (i.e.  saddle-shaped),  which  arti- 
NE<  culates  with  the  cartilaginous  surface  on  the  meta- 

carpal bone  of  the  thumb,  concave  and  convex  in  the  opposite 
directions.  This  peculiar  adaptation  of  the  two  surfaces  permits 
the  several  movements  of  the  thumb — viz.,  flexion,  extension, 
abduction  and  adduction  ;  consequently  circumduction.  Thus  we 
are  enabled  to  oppose  the  thumb  to  all  the  fingers,  which  is  one 


CARPO-METACAEPAL   JOINTS. 

of  the  great  characteristics  of  the  human  hand.  The  joint  is  sur- 
rounded by  a  fibrous  capsule  sufficiently  loose  to  admit  free  motion, 
and  stronger  on  the  dorsal  than  on  the  palmar  aspect.  The  security 
of  the  joint  is  increased  by  the  muscles  which  surround  it.  It  has 
a  separate  synovial  membrane. 

The  metacarpal  bones  of  the  fingers  are  con- 

CABPAL  JOINTS          nected  to  the  second  row  of  the  carpal  bones  by 

ligaments  upon  their  palmar  and  dorsal  surfaces. 

The  dorsal  ligaments  are"  the  stronger.  The  metacarpal  bone 
of  the  fore-finger  has  two  :  one  from  the  trapezium,  the  other  from 
the  trapezoid  bone.  That  of  the  middle  finger  has  also  two,  pro- 
ceeding from  the  os  magnum  and  the  os  trapezoides.  That  of  the 
ring  finger  has  also  two,  proceeding  from  the  os  magnum  and  the 
unciform  bone.  That  of  the  little  finger  has  one  only,  from  the 
unciform  bone. 

The  palmar  ligaments  are  arranged  nearly  upon  a  similar  plan. 
The  metacarpal  bone  of  the  fore-finger  has  one  from  the  trapezoid 
bone.  That  of  the  middle  finger  has  three,  proceeding  from  the 
trapezium,  the  os  magnum,  and  the  unciform  bone.  Those  of  the 
ring  and  little  fingers  have  each  one,  from  the  unciform  bone. 

Besides  the  preceding  ligaments,  there  is  another  of  consider- 
able strength,  called  the  interosseous.  It  proceeds  from  the  adjacent 
sides  of  the  os  magnum  and  the  os  unciforme,  descends  vertically, 
and  is  fixed  into  the  radial  side  of  the  metacarpal  bone  of  the  ring 
finger  (fig.  67).  This  ligament  isolates  the  synovial  membrane  of 
the  two  inner  metacarpal  bones  from  the  common  synovial  mem- 
brane of  the  carpus. 

Separate  the  metacarpal  bones  from  the  carpus,  and  observe  the 
relative  form  of  their  contiguous  surfaces.  The  metacarpal  bones 
of  the  fore  and  middle  fingers  are  adapted  to  the  carpus  in  such 
an  angular  manner  as  to  be  almost  immovable.  The  metacarpal 
bone  of  the  ring  finger,  having  a  plane  articular  surface  with  the 
unciform  bone,  admits  of  more  motion.  Still  greater  motion 
is  permitted  between  the  unciform  and  the  metacarpal  bone  of 
the  little  finger,  the  articular  surfaces  of  each  being  slightly  con- 
cave and  convex  in  opposite  directions.  The  greater  freedom  of 


JOINTS    OF    THE    FINGERS.  351 

motion  of  the  metacarpal  bone  of  the  little  finger  is  essential  to 
the  expansion  and  contraction  of  the  palm. 

The  carpal  extremities  of  the  metacarpal  bones  of  the  fingers 
are  connected  with  each  other  by  transverse  ligaments,  both  on 
their  dorsal  and  their  palmar  surfaces.  They  are  also  connected 
by  interosseous  ligaments,  which  extend  between  the  bones, 
immediately  below  their  contiguous  cartilaginous  surfaces. 

The  distal  extremities  of  these  bones  are  loosely  connected  on 
their  palmar  aspect  by  the  transverse  metacarpal  ligament. 

SYNOVIAL  MEM-         There   are   six    distinct    synovial    membranes, 
BRANES  OF  THE         proper  to  the  lower  end  of  the  radius,  and  the 
several  bones  of  the  carpus  (see  the  diagram,  p. 
347)  as  follows  : — 

a.  One  between  the  lower  end  of  the  radius  and  the  ulna. 

b.  One  between  the  radius  and  the  first  row  of  carpal  bones. 

c.  One  between  the  trapezium  and  the  metacarpal  bone  of  the 

thumb. 

d.  One  between  the  cuneiform  and  pisiform  bones. 

e.  One  between  the  first  and  second  rows  of  carpal  bones  (the 

intercarpal  joint).     This  extends  to  the  metacarpal  bones 
of  the  fore  and  middle  fingers. 
/.  One  between  the  unciform  bone  and  the  metacarpal  bones 

of  the  little  and  ring  fingers. 

FIRST  JOINT  OF          The  first  phalanx  of  the  finger  presents  a  shal- 
THE  FINGERS.  low  oval  cavity,  crusted  with  cartilage,  with  the 

broad  diameter  in  the  transverse  direction,  to  articulate  with  the 
round  .-cartilaginous  head  of  the  metacarpal  bone,  of  which  the 
articular  surface  is  elongated  in  the  antero-posterior  direction, 
and  of  greater  extent  on  its  palmar  than  its  dorsal  aspect.  This 
formation  of  parts  permits  flexion  of  the  finger  to  a  greater  degree 
than  extension  ;  and  also  a  slight  lateral  movement. 

Each  joint  is  provided  with  two  strong  lateral  ligaments,  and 
a  palmar. 

The  lateral  ligaments  arise  from  the  tubercles  on  either  side  of 
each  metacarpal  bone,  and  inclining  slightly  forward,  are  inserted 
into  the  sides  of  the  base  of  the  first  phalanx  of  the  finger. 


352  JOINTS   OP   THE    FINGERS. 

The  palmar  ligament  is  a  thick,  compact,  fibrous  struc- 
ture, which  extends  over  the  palmar  surface  of  the  joint.  Its 
lower  end  is  firmly  attached  to  the  base  of  the  first  phalanx  of  the 
finger;  its  upper  end  is  loosely  adherent  to  the  rough  surface 
above  the  head  of  the  metacarpal  bone.  On  either  side  it  is  in- 
separably connected  with  the  lateral  ligaments,  so  that  with  them 
it  forms  a  strong  capsule  over  the  front  and  sides  of  the  joint. 
Its  superficial  surface  is  slightly  grooved,  for  the  play  of  the  flexor 
tendons ;  its  deep  surface  is  adapted  to  cover  the  head  of  the  meta- 
carpal bone.  Two  sesamoid  bones  are  found  in  the  palmar  liga- 
ment belonging  to  the  joint  between  the  metacarpal  bone  and  the 
first  phalanx  of  the  thumb. 

The  palmar  ligaments  have  a  surgical  importance  for  the  follow- 
ing reason  : — In  dislocation  of  the  fingers,  the  facility  of  reduction 
mainly  depends  upon  the  extent  to  which  the  glenoid  ligament  is 
injured.  If  it  be  much  torn  there  is  but  little  difficulty :  if  entire, 
the  reduction  may  require  much  manipulation. 

These  joints  are  secured  on  their  dorsal  aspect  by  the  extensor 
tendon,  and  the  expansion  proceeding  from  it  on  either  side. 
Their  synovial  membranes  are  loose,  especially  beneath  the  extensor 
tendons. 

SECOND  AND  The    corresponding    articular    surfaces    of    the 

LAST  JOINT  OF  phalanges  of  the  fingers  and  thumb  are  so  shaped 
THE  FINGERS.  as  ^o  form  a  hinge-joint,  and,  therefore,  in- 

capable of  lateral  movement.  The  ligaments  connecting  them 
are  similar  in  every  respect  to  those  between  the  metacarpal  bones 
and  the  first  phalanges.  The  palmar  ligament  of  the  last  joint  of 
the  thumb  generally  contains  a  sesamoid  bone. 


353 


DISSECTION  OF  THE  ABDOMEN. 


ARBITRARY 
DIVISION  INTO 
REGIONS. 


These  lines  form 
FIG.  68. 


The  abdomen  is  divided  into  arbitrary  regions, 
that  the  situation  of  the  viscera  contained  in  it 
may  be  more  easily  described.  For  this  purpose 
we  draw  the  following  lines : — one  horizontally  across  the  abdomen 
on  a  level  with  the  cartilages  of  the  ninth  ribs ;  another  on  a  level 
with  the  anterior  superior  spines  of  the  ilia, 
the  boundaries  of  three  spaces,  each 
of  which  is  subdivided  into  three 
regions  by  a  vertical  line  drawn  on 
each  side  from  the  cartilage  of  the 
eighth  rib  to  the  middle  of  Poupart's 
ligament.  Thus,  there  are  a  central 
and  two  lateral  regions  in  each  space. 
The  central  region  of  the  upper  space 
is  termed  the  epigastric ;  the  central 
one  of  the  middle  space  is  called  the 
umbilical  region  ;  and  the  central  of 
the  inferior  space,  the  hypogastric 
region.  The  lateral  regions  of  the 
spaces  from  above  downwards  are 
termed  the  right  and  left  hypo- 
chondriac, the  right  and  left 
lumbar,  and  the  right  and  left 
inguinal  or  iliac  regions,  respectively. 

The  abdomen  should  be  distended  with  air,  by  means  of  a 
blowpipe  inserted  into  the  abdominal  cavity  at  the  umbilicus. 

_.  An  incision  should  be  made  from  the  sternum 

DISSECTION.  . 

to  the  pubes,  another  from  the  anterior  spine  of  the 

A   A 


354 


SUPEEFICIAL   VESSELS    OF   THE    GEOIN. 


ilium  to  a  point  midway  between  the  umbilicus  and  pubes,  and 
a  third  from  the  ensiform  cartilage,  transversely  outwards  towards 
the  axilla  as  far  as  the  angles  of  the  ribs.  The  skin  should  then 
be  dissected  from  the  subjacent  adipose  and  connective  tissue, 
called  the  superficial  fascia. 

FIG.  69. 


SUPERFICIAL    VESSELS    AND    GLANDS    OF   THE    GHOIN. 


1.  Saphenous  opening  of  the  fascia  lata. 

2.  Saphena  vein. 

3.  Superficial  epigastric  a. 

4.  Superficial  circmnflexa  ilii  a. 


5.  Superficial  pudic  a. 

6.  External  abdominal  ring. 

7.  Fascia  lata  of  the  thigh. 


SUPERFICIAL 
FASCIA. 


The  subcutaneous  tissue  of  the  abdomen  has 
the  same  general  characters  as  that  of  other 
parts,  and  varies  in  thickness  in  different  persons,  according  to 
the  amount  of  fat.  At  the  lower  part  of  the  abdomen,  it  admits  of 
separation  into  two  layers,  between  which  are  found  the  sub- 


SUPERFICIAL   VESSELS   OP   THE    GROIN.  355 

cutaneous  blood-vessels,  the  lymphatic  glands,  the  ilio-inguinal 
nerve,  and  the  hypogastric  branch  of  the  ilio-hypogastric  nerve. 

Eespecting  the  superficial  layer,  observe  that  it  contains  the 
fat,  and  is  continuous  with  the  superficial  fascia  of  the  thigh,  the 
scrotum,  and  the  perineum.  The  deeper  layer  is  intimately  con- 
nected with  Poupart's  ligament  and  the  linea  alba ;  but  it  is  very 
loosely  continued  over  the  spermatic  cord  and  the  scrotum,  and 
becomes  identified  with  the  deep  layer  of  the  superficial  fascia  of 
the  perineum.  These  points  deserve  attention,  since  they  explain 
how  urine,  extravasated  into  the  perineum  and  scrotum,  readily 
makes  its  way  over  the  spermatic  cord  on  to  the  surface  of  the  ab- 
domen ;  but  from  this  it  cannot  travel  down  the  thigh,  on  account 
of  the  connection  of  the  fascia  with  Poupart's  ligament. 

„  Between  the  layers  of  the  superficial  fascia  on 

SUPERFICIAL  .  •*  r 

BLOOD-VESSELS  the  groin  and  upper  part  of  the  thigh,  are  several 
AND  LYMPHATIC  lymphatic  glands  and  small  blood-vessels  (fig.  69). 
GLANDS.  ij^g  gjan(jg  are  named,  according  to  their  situation, 

inguinal  or  femoral.  The  inguinal,  from  three  to  four  in  number, 
are  often  small,  and  escape  observation.  They  are  of  an  oval  form, 
with  their  long  axis  corresponding  to  the  line  of  the  crural  arch 
(represented  by  the  dark  line  in  fig.  69).  They  receive  the  super- 
ficial lymphatics  from  the  lower  part  of  the  wall  of  the  abdomen, 
from  the  scrotum,  penis,  perineum,  anus,  and  gluteal  region,  and 
are  therefore  generally  affected  in  venereal  disease.  The  lymph- 
atics from  the  upper  part  of  the  abdominal  parietes  terminate  in 
the  lumbar  glands. 

The  superficial  arteries  in  the  neighbourhood  arise  from  the 
femoral.  One,  the  superficial  epigastric,  ascends  over  Poupart's 
ligament  and  ramifies  over  the  lower  part  of  the  abdomen,  as  high 
as  the  umbilicus,  inosculating  with  the  deep  epigastric  artery  ; 
another,  the  superficial  external  pudic,  crosses  the  spermatic 
cord,  and  is  distributed  to  the  skin  of  the  penis  and  scrotum ;  a 
third,  the  superficial  circumflexa  ilii,  ramifies  towards  the  spine 
of  the  ilium.  These  subcutaneous  arteries,  the  pudic  especially, 
often  occasion  a  free  hemorrhage  in  the  operation  for  strangulated 
hernia. 

A  A   2 


356  ABDOMINAL   MUSCLES. 

The  corresponding  veins  join  the  saphena  vein  of  the  thigh. 
Under  ordinary  circumstances  they  do  not  appear  in  the  living 
subject ;  but  when  any  obstruction  occurs  in  the  inferior  vena 
cava,  they  become  enlarged  and  tortuous,  and  constitute  the  chief, 
channels  through  which  the  blood  would  be  returned  from  the 
lower  limbs.* 

CUTANEOUS  The  skin  of  the  abdomen  is  supplied  with  nerves 

NERVES.  after   the   same   plan  as   the   chest :  namely,  by 

lateral  and  anterior  branches  derived  from  the  five  or  six  lower 
intercostal  nerves,  as  follows  : — 

a.  The  lateral  cutaneous  nerves  come  out  between  the  digita- 
tions  of  the  external  oblique  muscle,  in  company  with  small 
arteries,  and  divide  into  anterior  and  posterior  branches;  the 
anterior  supply  the  skin  as  far  as  the  rectus ;  the  posterior,  the 
skin  over  the  latissimus  dorsi.  The  lateral  branch  of  the  twelfth 
dorsal  nerve  is  larger  than  the  others,  and  passes  over  the  crest 
of  the  ilium  to  the  skin  of  the  buttock,  without  dividing  like 
the  other  nerves.  'The  corresponding  branch  of  the  first  lumbar 
has  a  similar  distribution. 

6.  The  anterior  cutaneous  nerves  emerge  with  small  arteries 
through  the  sheath  of  the  rectus.  They  are  not  only  smaller 
than  the  lateral  nerves,  but  their  number  and  place  of  exit  is  less 
regular.  That  which  comes  through  the  external  abdominal  ring 
(ilio-inguinal\  as  well  as  that  which  comes  through  the  wall  of 
the  abdomen  just  above  it  (the  hypogastric  branch  of  the  ilio- 
hypogastric},  are  derived  from  the  first  lumbar  nerve.  These, 
however,  are  but  repetitions  of  the  others,  and  supply  the  skin  of 
the  groin  and  scrotum  in  the  male,  and  the  labium  pudendi  in  the 
female. 

A  small  nerve — namely;  the  genital  branch  of  the  genito-crural 
— comes  through  the  external  ring.  <Jt  lies  behind  the  cord  close 
to  the  outer  pillar. 

DISSECTION.  The  deep  layer  of  the  superficial  fascia  should 

now  be  removed  from  the  external  oblique,  by  commencing  at  the 

*  A  cast  in  illustration  of  this  is  preserved  in  the  Museum  of  St.  Bartholomew's 
Hospital. 


ABDOMINAL    MUSCLES.  357 

fleshy  portion  of  the  muscle,  and  working  in  the  course  of  its  fibres. 
Care  must  be  taken  not  to  remove  any  of  its  aponeurosis,  which 
is  very  thin.  The  digitations  of  this  muscle  with,  the  serratus 
magnus  and  latissimus  dorsi  must  also  be  made  outt 

MUSCLES  OF  THE         The  abdominal  muscles,  three   on   each   side, 
ABDOMINAL  are  arranged  in  strata,  named,  after  the  direction 

of  their  fibres,  the  external  oblique,  internal 
oblique,  and  transversalis.  They  terminate  in  front  in  strong 
aponeuroses,  arranged  so  as  to  form  a  sheath  for  a  broad  muscle, 
called  the  rectus,  which  extends  perpendicularly  on  each  side  the 
linea  alba  from  the  sternum  to  the  pubes. 

EXTEENAL  OB-           This  muscle  arises  from  the  eight  or  nine  lower 
UQUE.  ribs,  by  as  many  pointed  bundles,  called  digita- 

tions. The  upper  five  of  these  interdigitate  with  similar  bundles 
of  the  serratus  magnus ;  the  three  lower  correspond  in  like  manner 
with  the  origin  of  the  latissimus  dorsi ;  but  they  cannot  be  seen 
unless  the  body  be  turned  on  the  side.  The  upper  part  of  this 
muscle  descends  obliquely  forwards,  and  terminates  in  the  apo- 
neurosis of  the  abdomen ;  the  lower  proceeds  almost  perpendicu- 
larly from  the  last  ribs,  and  is  inserted  into  the  outer  lip  of 
more  than  the  anterior  half  of  the  crest  of  the  ilium.* 

The  aponeurosis  of  the  external  oblique  increases  in  strength, 
breadth,  and  thickness,  as  it  approaches  the  lower  margin  of  the 
abdomen,  this  being  the  situation  where  the  greater  pressure  of 
the  viscera  requires  the  most  effective  support.  Its  tendinous 
fibres  take  the  same  direction  as  the  muscle,  and  form  by  their 
decussation  in  the  middle  line  the  linea  alba,  which  extends  from 
the  ensiform  cartilage  to  the  pubes. 

POTJPART'S  Along   the   line   of  junction   of   the  abdomen 

LIGAMENT  OK  with,  the  thigh,  the  aponeurosis  extends  from  the 

CRTTRAL  ARCH.  .  .  •  ,.  ,,        .-.,  ,, 

anterior  superior  spine  ot  the  ilium  to  the  spine 

of  the  pubes,  and  forms  an  arch  over  the  intermediate  bony  exca-. 
vation  (p.  358).  This,  which  is  termed  the  crural  arch,  or  more 

*  From  its  position  and  the  direction  of  its  fibres,  it  is  manifest  that  the  ex- 
ternal oblique  represents,  in  the  abdomen,  the.  external  intercostal  muscles  of.  the, 
chest. 


358 


ABDOMINAL   MUSCLES. 


commonly  Poupart's  ligament,*  transmits   the   great  vessels  of 
the  thigh,  with  muscles  and  nerves. 

This  ligament,  when  not  separated  from  its  fascial  connections, 
does  not  run  straight  from  the  spine  of  the  ilium  to  that  of 
the  pubes,  but  is  slightly  curved,  with  its  convexity  towards  the 
thigh.  Above,  and  somewhat  to  the  outer  side  of  the  spine 
of  the  pubes,  is  situated  an  opening  in  the  aponeurosis,  called 

Fio.  70. 


1.  External     abdominal 

ring. 

2.  Gimbernat's  ligament. 

3.  Poupart's  ligament,  or 

outer  pillar  of  the 
ring. 


4.  Internal  pillar  of  the 

ring. 

5.  Position  of  the  inter- 

nal ring,  in  dotted 
outline. 


DIA3RAM   OF   POUPART  S    LIGAMENT,    OF    THE    APONEUBOSIS    OF   THE    EXT  EKNAL    OBLIQUE, 
AND   OF   THE   EXTERNAL   ABDOMINAL    EING. 

the  external  abdominal  ring.  In  the  male  it  is  a  triangular 
opening  about  an  inch  long,  with  its  base  at  the  pubes,  and  will 
admit  the  passage  of  a  finger ;  it  transmits  the  spermatic  cord. 
In  the  female  it  is  smaller  and  transmits  the  round  ligament  of 
the  uterus.  It  is  bounded  by  the  free  margins  of  the  aponeurosis 

*  This  was  first  described  by  Fallopius,  an  Italian  anatomist,  in  his  '  Observa- 
tiones  Anatomicse,'  published  in  1561.  It  was  subsequently  described  by  Poupart 
in  1705,  in  the  'M6m.  de  1'Acad.  de  Paris,'  and  is  now  commonly  called  'Poupart's 
ligament.' 


ABDOMINAL    MUSCLES.  859 

which  are  termed  its  columns  or  pillars.  The  inner  pillar  (No.  4 
in  the  diagram)  is  thin,  and  is  attached  to  the  front  of  the  pubes, 
decussating  with  its  fellow  of  the  opposite  side  in  front  of  the 
symphysis.  The  outer  pillar  is  thicker  and  stronger,  and  has  three 
attachments  ;  one,  into  the  spine  of  the  pubes — Poupart's  ligament 
(No.  3) ;  another,  for  nearly  an  inch  along  the  linea  ilio-pectinea — 
Gimbernafs  ligament  (No.  2);  the  third — or  triangular  ligament 
— consists  of  a  few  fibres  which  pass  .obliquely  upwards  and  inwards 
beneath  the  inner  pillar  as  far  as  the  linea  alba,  where  they  are 
continuous  with  the  aponeurosis  of  the  opposite  side.  At  the  lower 
part  of  the  aponeurosis  of  the  external  oblique,  there  are  some 
arched  fibres  called  intercolumnar  bands,  which  are  strongest  above 
the  external  ring.  Their  use  is  to  strengthen  the  opening  and 
prevent  the  ring  from  enlarging. 

Attached  to  the  pillars  of  the  external  ring  is  a  thin  fascia, 
the  intercolumnar  or  spermatic  fascia,  which  is  prolonged  over 
the  spermatic  cord  and  testis,  and  thus  forms  one  of  the  coverings 
of  that  organ. 

The  spermatic  cord  in  its  passage  through  the  ring  rests  upon 
the  external  pillar. 

The  external  oblique  should  now  be  detached 
from  the  ribs  and  the  crest  of  the  ilium,  and 
turned  forwards  as  far  as  this  can  be  done  without  injuring  its 
aponeurosis  or  the  crural  arch.  The  second  muscular  stratum 
will  thus  be  exposed  and  recognised  by  the  difference  in  the  direc- 
tion of  its  fibres,  which  run  upwards  and  inwards. 

INTERNAL  This   muscle  arises  by  fleshy  fibres  from  the 

OBLIQUE.  outer  half  of  Poupart's  ligament,  from  the  anterior 

two-thirds  of  the  middle  lip  of  the  crest  of  the  ilium,  and  from 
the  fascia  lumborum.*  The  fibres  ascend  obliquely  and  are 
inserted  as  follows : — the  posterior,  into  the  cartilages  of  the  three 
or  four  lower  ribs  ;  the  middle,  into  the  abdominal  aponeurosis ; 
and  the  anterior  (which  arise  from  Poupart's  ligament)  arch  in- 
wards over  the  spermatic  cord,  and  descend  somewhat  to  be  in- 

*  The  internal  oblique  represents,  in  the  abdomen,  the  internal  intercostal  muscles 
of  the  thorax. 


360 


ABDOMINAL    MUSCLES. 


serted,  in  common  with  the  tendon  of  the  transversalis  muscle 
into  the  pubes  and  for  a  short  distance  into  the  linea  ilio-pectinea, 
immediately  behind  the  external  ring. 

The  aponeurosis  of  the  internal  oblique  is  the  broad  expanded 
tendinous  tissue  into  which  the  muscle  is  anteriorly  attached.  It 
extends  from  the  chest  to  the  pelvis,  and  its  fibres  run  in  the  same 
direction  as  the  muscle.  At  the  outer  border  of  the  rectus  it  splits 
into  two  layers  :  an  anterior,  which  passes  in  front  of  the  rectus 
in  conjunction  with  the  aponeurosis  of  the  external  oblique ;  and 

FIG.  71. 


1.  Conjoined  tendon  of 
internal  oblique  and 
transversalis. 


2.  Cremaster  muscle 
passing  down  in 
loops  orer  the 
cord. 


DIAGRAM    OF    THE    LOWER   FIBRES    OF   THE    INTERNAL   OBLIQUE    AND    TRANSVERSALIS, 
WITH    THE    CREMASTER    MUSCLE. 

a  posterior,  which,  in  common  with  the  aponeurosis  of  the 
transversalis,  passes  behind  the  rectus.  The  two  layers  thus 
form  a  sheath  for  the  rectus,  which,  except  at  the  lower  fourth 
behind,  is  complete.  Midway  between  the  umbilicus  and  the  pubes, 
the  aponeuroses  of  all  the  three  muscles  pass  in  front  of  the  rectus, 
so  that  posteriorly  in  this  situation  it  has  no  sheath.  The  lower 
free  border  of  the  posterior  part  of  the  sheath*  marks  the  situation 
where  the  deep  epigastric  artery  enters  the  substance  of  the  rectus. 
*  Sometimes  called  the  '  semilunar  fold  of  Douglas.' 


ABDOMINAL   MUSCLES.  361 

CREMASTER  The  cremaster  is  a  thin  pale  muscle,  or  the 

MUSCLE.  reverse,  according  to  the  condition  of  the  subject. 

It  is  best  to  regard  it  as  a  detachment  of  the  lowest  fibres  of 
the  internal  oblique,  which,  proceeding  from  Poupart's  ligament, 
descend  in  front  of  the  spermatic  cord,  and  then  arch  up  again 
to  the  spine  and  crest  of  the  pubes,  forming  loops  of  different 
lengths ;  some  reaching  only  as  low  as  the  external  ring,  others 
lower  still,  whilst  the  lowest  spread  out  over  the  tunica  vaginalis 
of  the  testis.  The  muscular  fibres  are  frayed  out,  being  connected 
by  loose  cellular  tissue,  and  form  a  covering  for  the  testis,  called 
the  cremasteric  fascia.  This  muscle  is  absent  in  the  female.  Its 
nerve  comes  from  the  genital  branch  of  the  genito-crural,  and  its 
artery  (cremasteric)  from  the  deep  epigastric. 

The  internal  oblique    should  now  be  detached 
DISSECTION.  n 

from  the  ribs  and  the  crest  of  the  ilium,  and  turned 
forwards,  without  disturbing  that  portion  of  it  connected  with  the 
crural  arch.  To  avoid  cutting  away  any  part  of  the  transversalis 
in  reflecting  the  internal  oblique,  dissect  near  the  crest  of  the  ilium, 
and  search  for  an  artery  which  runs  between  these  muscles  and 
may  be  followed  as  a  guide.  This  artery,  called  the  deep  circum- 
ftexa  ilii,  is  a  branch  of  the  external  iliac,  and  supplies  the  abdo- 
minal muscles.  Beneath  the  internal  oblique  the  continuations  of 
the  intercostal  nerves  and  vessels  are  brought  into  view.  These 
should  be  preserved. 

TRANSVERSALIS          This  muscle   arises   from   the    outer   third  of 
ABDOMINIS.  Poupart's  ligament,  from  the  anterior  two-thirds 

of  the  crest  of  the  ilium,  from  a  strong  fascia  attached  to  the 
transverse  processes  of  the  lumbar  vertebrae,  and,  lastly,  from  the 
inner  surfaces  of  the  six  or  seven  lower  costal  cartilages,  by  digita- 
tions  which  correspond  with  those  of  the  diaphragm.  From  this 
origin  the  fibres  pass  horizontally  forwards  and  terminate  an- 
teriorly in  a  broad  aponeurosis.  Some  of  its  fibres  arch  down- 
wards, and  are  inserted  with  some  fibres  of  the  internal  oblique  by 
means  of  a  conjoined  tendon  into  the  pubes. 

The  aponeurosis  into  which  the  fibres  are  inserted  is  broader 
below  than  above,  and  forms  part  of  the  posterior  sheath  of  the 
rectus,  excepting  in  the  lower  fourth,  where  it  passes  entirely  in  front. 


362 


ABDOMINAL    MUSCLES. 


KECTUS  This  long  muscle  is  situated  vertically  in  front 

ABDOMINIS.  of  ^e  abdomen,  and  is  enclosed  in  a  sheath  formed 

by  the  aponeuroses  of  the  lateral  muscles  of  the  abdomen.  To 
expose  it,  therefore,  slit  up  the  middle  of  the  sheath,  and  reflect 
the  two  halves.  It  arises  by  two  tendons,  the  inner  and  smaller 
of  which  is  attached  to  the  symphysis,  the  outer  to  the  crest  of 
the  pubes.  As  the  fibres  pass  up,  the  muscle  becomes  broader  and 
thinner,  and  is  inserted  into  the  fifth,  sixth,  and  seventh  costal 
cartilao'es.  Notice  the  tendinous  intersections  across  the  muscle 

O 

called  linece  transversce,  which  are  incomplete  repetitions  of  the 
ribs  in  the  wall  of  the  abdomen.*  Their  number  varies  from 
three  to  five,  but  there  are  always  more  above  than  below  the 
umbilicus.  These  tendinous  intersections  adhere  closely  to  the 
FlG  72.  sheath  in  front,  but  not 

behind ;  consequently, 
pus  formed  between  the 
front  of  the  rectus  and 
its  sheath  would  be  con- 
fined by  two  intersec- 
tions; not  so  on  the 
back  of  the  muscle, 
where  pus  might  travel 
down  the  entire  length 
of  it. 

The  sheath  of  the 
rectus  consists  in  front 
of  the  aponeurosis  of 
the  external  oblique, 


ERECTOR     SP. 


TRANSVERSE    SECTION    THEOUGH    THE    ABDOMINAL    MUS- 
CLES   TO    SHOW    THE    FORMATION    OF    THE    SHEATH  OF 
THE  RECTUS,    THE     QUADBATUS     LUMBOHUM   AXU    THE     and     half     the 
ERECTOR 


oblique ;  while  the  back  of  the  sheath  comprises  the  aponeurosis 
of  the  transversalis,  and  half  that  of  the  internal  oblique  (fig,  71). 
This,  however,  applies  only  to  the  upper  three-fourths  of  the 
muscle ;  the  lower  fourth  has  no  sheath  behind,  since  all  the 
aponeuroses  pass  in  front  of  it. 

*  Some  animals — e.g.  the  crocodile — have  bony  abdominal  ribs. 


ABDOMINAL    MUSCLES.  363 

p^  This  small  triangular  muscle  is  situated  near 

the  pubes,  close  to  the  linea  alba,  and  has  a 
sheath  of  its  own.  It  arises  from  the  upper  part  of  the  pubes  in 
front  of  the  rectus,  and  terminates  in  the  linea  alba  about  mid- 
way between  the  pubes  and  the  umbilicus.  It  is  often  absent  on 
one  or  even  both  sides. 

Linea  alba.  — The  aponeuroses  of  the  abdominal  muscles  decus- 
sate along  the  middle  line  and  form  a  white  fibrous  band,  extending 
from  the  ensiform  cartilage  to  the  pubes.  This  is  the  linea  alba: 
it  is  the  fibrous  continuation  of  the  sternum  and  is  broader  above 
than  below.  A  little  lower  than  the  middle  is  the  umbilicus. 

The  linea  alba,  being  the  thinnest  part  of  the  abdomen,  and 
free  from  large  blood-vessels,  is  chosen  as  a  safe  line  for  tapping  in 
dropsy,  for  puncturing  the  bladder  in  retention  of  urine,  and  for 
ovariotomy. 

Linece  semilunares. — These  are  the  two  slightly  curved  lines, 
on  the  front  of  the  abdomen,  corresponding  with  the  outer  margins 
of  the  two  recti  muscles.  They  are  formed  by  the  junction  of  the 
aponeuroses  of  the  lateral  muscles." 

The  abdominal  muscles  serve  many  important  purposes : — 
FUNCTIONS  OF  l^-  ^n  tranquil  expiration  they  push  the  dia- 

THE  ABDOMINAL        phragm  upwards  by  gentle  pressure  on  the  abdo- 
minal viscera. 

In  forcible  expiration  the  same  process  takes  place,  but  with 
greater  energy.  This  is  variously  exemplified  in  coughing, 
sneezing,  and  laughing. 

2nd.  In  vomiting,  the  diaphragm  being  fixed*  by  the  closure 
of  the  glottis,  the  abdominal  muscles  contract,  and  assist  the  sto- 
mach to  expel  its  contents. 

3rd.  In  conjunction  with  the  contracted  diaphragm,  they 
assist  the  muscular  walls  of  the  bladder  and  rectum  in  the  expul- 
sion of  urine  and  faeces,  and  the  action  of  the  uterus  in  partu- 
rition. They  exercise  a  gentle  pressure  and  support  on  the 
abdominal  viscera,  and  shield  them  from  injury  by  strongly  con- 
tracting when  a  blow  is  anticipated. 

*  By  the  term  '  fixed,'  it  is  meant  that  the  diaphragm  forms  a  resisting  surface. 


364  PAETS    CONCEENED    IN   INGUINAL   HEENIA. 

4th.  They  are  movers  of  the  trunk  in  various  ways.  For 
example,  the  right  external  oblique  acting  with  the  left  internal 
oblique  will  rotate  the  chest  towards  the  left  side,  as  in  mowing, 
and  vice  versa. 

The  rectus  is  chiefly  concerned  in  raising  the  body  from  the 
horizontal  position,  as  anyone  may  ascertain  by  placing  his  hand 
on  the  abdomen  while  rising  from  the  ground. 

By   dividing  the  rectus  transversely  near  the 
DISSECTION.  . 

umbilicus,   and  raising  it  from  its  position,  we 

have  a  complete  view  of  the  manner  in  which  the  sheath  is 
formed;  we  observe,  too,  that  this  is  absent  behind  the  lower  fourth 
of  the  muscle.  Eamifying  in  the  substance  of  the  muscle  is  a 
large  artery,  called  the  deep  epigastric,  a  branch  of  the  external 
iliac ;  also  the  continuation  of  the  internal  mammary,  which  de- 
scends from  the  subclavian. 

NEBVES  OF  THE  These  nerves  are  the  continuations  of  the  six  lower 
ABDOMINAL  WALL,  intercostal  nerves,  and  of  the  first  lumbar.  They 
have  the  same  general  course  and  distribution.  They  run  forwards 
under  the  costal  cartilages  between. the  internal  oblique  and  trans- 
versalis  towards  the  rectus.  They  furnish  branches  to  the  ab- 
dominal muscles,  and  each  gives  off  its  lateral  and  anterior  cu- 
taneous branches,  described  p.  150. 

The  transversalis  muscle  must  now  be  reflected 
with  the  rectus*  by  incisions  similar  to  those  for 
the  reflection  of  the  aponeurosis  of  the  external  oblique.  The 
parts  must  be  disturbed  as  little  as  possible,  so  that  the  bearing 
of  the  transversalis  fascia  in  reference  to  the  anatomy  of  the  parts 
concerned  in  hernia  may  be  thoroughly  examined. 


DISSECTION   OF    THE    PARTS    CONCERNED   IN   INGUINAL    HERNIA. 

FASCIA  TKANS-           This  fascia  is  so  called  because  it  lies  in  contact 
VERSALIS.  with    the   posterior    surface    of    the  transversalis 

muscle.     It  is  comparatively  thin,  superiorly,  where  it  is   conti- 
nuous with  the  fascia   on  the  under  surface  of  the   diaphragm. 


PAETS    CONCERNED    IN    INGUINAL    HERNIA. 


365 


Inferiorly,  it  is  attached  to  the  crest  of  the  ilium  and  to  Poupart's 
ligament,  where  it  becomes  continuous  with  the  fascia  covering  the 
iliacus  internus  (fascia  iliaca).  About  the  middle  of  Poupart's 
ligament  it  sends  a  funnel-shaped  prolongation  downwards  into 
the  thigh,  forming  the  anterior  part  of  the  sheath  of  the  femoral 
vessels.  Its  inner  border  is  connected  with  the  margin  of  the 
rectus,  to  the  lower  margin  of  the  conjoined  tendon,  and  also 
to  the  pubes.  This  fascia  is  strongest  just  behind  the  external 

FIG.  73. 


1.  Internal   abdominal 

ring. 

2.  Position  of  the  ex- 

ternal abdominal 
ring  in  dotted  out- 
line. 

3.  Epigastric     a.       in 

dotted  outline. 


4, 4.  Sheath  of  the  femo- 
ral vessels,  con- 
tinued from  the 
fascia  transver- 
salis. 

5.  Femoral  a. 

6.  Profunda  a. 

7.  Saphena  v. 

8,  8.  Fascia  transyer- 
salis. 


DIAGRAM    OF   THE   FASCIA   TKANSVEESALIS    SEEN    FROM    THE   FRONT. 

abdominal  ring,  and,  but  for  it  and  the  conjoined  tendon,  there 
would  be  a  direct  opening  into  the  abdominal  cavity  through 
the  external  ring.  The  outer  half  of  the  fascia  is  very  firmly 
connected  to  Poupart's  ligament  and  to  the  fascia  iliaca;  but 
the  inner  half  is  loosely  connected  with  the  crural  arch,  and  passes 
down  under  it,  as  before  stated,  over  the  femoral  vessels  into  the 
thigh,  and  forms  the  front  of  what  is  termed  the  femoral  sheath. 

INTERNAL  As-  The  opening  in  the  fascia  transversalis  through 

DOMINAL  BING.          which   the   spermatic   cord   passes  is  called    the 


366  PARTS    CONCERNED    IN   INGUINAL    HERNIA. 

internal  abdominal  ring  (or  the  inner  aperture  of  the  inguinal 
canal).  It  corresponds  to  a  point  midway  between  the  anterior 
superior  spine  of  the  ilium  and  the  spine  of  the  pubes,  and  about 
two- thirds  of  an  inch  above  the  crural  arch.  It  is  oval  with  the 
long  diameter  nearly  vertical ;  its  margin  is  well  defined  on  the 
inner,  but  not  on  the  outer  side,  and  from  its  border  is  continued 
forwards  a  funnel-shaped  prolongation  over  the  spermatic  cord, 
which  passes  through  the  ring.  This  covering,  thin  and  delicate, 
is  termed  the  infundibuliform  fascia.  (This  is  not  seen  in  the 
diagram.)  Close  by  the  inner  border  of  the  internal  ring,  the  deep 
epigastric  artery  ascends  to  enter  the  substance  of  the  rectus. 

To  see  that  part  of  the  peritoneum  concerned 
in  inguinal  hernia,  the  fascia  transversalis  must 
be  removed  by  incisions  similar  to  those  recommended  before. 
The  fascia  is  easily  separable  from  the  peritoneum  which  is  situ- 
ated immediately  behind  it.  The  peritoneum  at  the  inner  ring 
presents  a  well-marked  depression,  which  varies,  however,  consi- 
derably :  in  some  being  scarcely  visible ;  in  others,  being  continued 
downwards  into  the  inguinal  canal,  in  the  form  of  a  pouch.  In 
some  instances,  a  communication  is  found  between  the  general 
cavity  of  the  peritoneum  and  the  tunica  vaginalis  testis. 

INGUINAL  Having   examined   the  several   strata  through 

CANAL.  which  the  spermatic  cord  passes,  replace  them  in 

their  natural  position,  and  examine  the  inguinal  canal  as  a  whole. 
Its  direction  is  obliquely  downwards  and  inwards.  Its  length  in  a 
well-formed  adult  male  is  from  one  and  a  half  to  two  inches.  It 
is  bounded  in  front  by  the  aponeurosis  of  the  external  oblique, 
and  externally  by  a  small  portion  of  the  internal  oblique;  behind, 
by  the  fascia  transversalis  and  the  conjoined  tendon  of  the 
internal  oblique  and  transversalis ;  above.,  by  the  lower  fleshy  fibres 
of  the  internal  oblique  and  transversalis ;  below,  by  the  crural 
arch. 

p  From  a  surgical  point  of  view  this  is  one  of  the 

EELATIONS  OF  THE  most  important  arteries  in  the  body.  It  arises 
DEEP  EPIGASTRIC  from  the  external  iliac,  just  before  this  vessel 
AETEEY.  passes  under  the  crural  arch.  It  ascends  inwards 


PARTS  CONCERNED  IN  INGUINAL  HERNIA.        367 

between  the  fascia  transversalis  and  the  peritoneum,  forms  a  gentle 
curve  on  the  inner  side  of  the  internal  abdominal  ring,  and  conse- 
quently on  the  inner  side  of  the  spermatic  cord,  and  then  enters 
the  rectus  muscle  below  the  edge  of  the  sheath. 

The  artery  runs  in  the  substance  of  the  rectus  parallel  with  the 
linea  alba,  and  is  accompanied  by  two  veins,  of  which  the  larger  is 
on  its  inner  side.  They  terminate  by  a  single  trunk  in  the  iliac 
vein. 

BRANCHES  OF  The  pubic  is  the  most  important  branch.     It 

THE  DEEP  EPI-  •  runs  inwards,  behind  the  crural  arch,  towards  the 
GASTHIC.  pubes,  behind  which  it  anastomoses  with  the  pubic 

branch  of  the  obturator.  Sometimes  the  obturator  artery  is  absent, 
in  which  case  the  pubic  branch  of  the  epigastric  enlarges  and  takes 
the  place  of  the  absent  vessel.  It  derives  its  chief  practical  in- 
terest from  the  fact  that  it  is  liable  to  be  wounded  in  dividing  the 
stricture  in  femoral  hernia.*  But  its  size  varies  in  different  sub- 
jects, and  is  sometimes  so  small  as  to  escape  observation.  The 
second  branch  is  the  cremasteric.  It  supplies  the  coverings  of  the 
cord,  but  chiefly  the  cremaster  muscle.  After  giving  off  other 
unnamed  muscular  branches  the  main  trunk  terminates  in  the 
rectus  by  inosculations  with  the  internal  mammary. 

DEEpCmcuM-  The  deep  circumflexa  ilii  artery  is  a  branch  of 

FLEXA  lui.  the  external  iliac,  just  above  the  crural  arch ;  it 

runs  upwards  and  outwards  parallel  with  Poupart's  ligament,  and 
at  the  middle  of  the  crest  of  the  ilium  pierces  the  transversalis 
muscle,  and,  running  in  the  same  direction,  lies  between  the 
transversalis  and  internal  oblique.  It  anastomoses  with  the  ilio- 
lumbar  artery,  and  sends  small  muscular  branches,  which  run 
upwards,  and  communicate  with  the  epigastric  and  the  lumbar 
arteries. 

The  circumflex  iliac  vein  crosses  the  external  iliac  artery  and 
opens  into  the  external  iliac  vein. 

Such  is  an  outline  of  the  anatomy  of  the  parts  concerned  in 

*  There  is  a  preparation  (No.  83,  Ser.  17)  in  the  Museum  of  St.  Bartholomew's 
Hospital  quite  to  the  point.  The  patient  had  profuse  haemorrhage,  which  com- 
menced five  hours  after  the  operation.  He  died  from  peritonitis. 


368  PARTS   CONCERNED    IN   INGUINAL   HERNIA. 

inguinal  hernia.  The  description  applies  equally  to  the  female, 
provided  the  round  ligament  be  substituted  for  the  spermatic 
cord.  The  inguinal  canal  is  proportionately  smaller,  and  there 
is  no  cremaster. 

PRACTICAL  The  testis  originally  formed  in  the  loins  passes, 

APPLICATION.  about  the  eighty  month   of  foetal  life,  from  the 

abdomen  into  the  scrotum,  through  an  oblique  canal  in  the  wall 
of  the  abdomen,  called  the  inguinal  canal.  A  portion  of  peri- 
toneum is  pouched  out  before  the  descending  testis,  and  consti- 
tutes the  tunica  vaginalis  testis,  "The  blood-vessels,  nerves,  and 
vas  deferens  pass  down  with  •the  testis,  and  constitute  the  sper- 
matic cord.  The  inguinal  canal  runs  obliquely  through  the  abdo- 
minal wall,  that  it  may  the  better  resist  the  protrusion  of  intestine. 

The  wall  of  the  abdomen,  as  previously  stated,  is  composed  of 
various  strata,  and  the  testis  and  cord  in  their  passage  through 
each  stratum  derive  from  each  a  covering  similar  in  structure  to 
the  stratum  itself.  Of  these  strata  there  are  three :  the  first, 
proceeding  from  within  outwards,  is  the  fascial  stratum  derived 
from  the  fascia  transversalis ;  the  second  is  the  muscular  stratum 
(cremasteric)  from  the  internal  oblique  and  transversalis  muscles ; 
the  third  is  the  aponeurotic  stratum  from  the  external  oblique. 

The  passage  of  the  testis  through  the  lower  part  of  the  ab- 
dominal parietes  (inguinal  canal)  occasions,  at  this  part  of  the 
belly,  a  natural  weakness  which,  associated  with  other  conditions, 
favours  the  protrusion  of  intestine  in  this  situation. 

A  protrusion  of  intestine  through  any  part  of  the  inguinal  canal 
is  called  an  inguinal  hernia. 

OBLIQUB  The  most  common  form  of  inguinal  hernia  is 

INGUINAL  HEENIA.  that  in  which  a  portion  of  intestine  protrudes 
first  through  the  internal  ring,  then,  traversing  the  inguinal 
canal,  emerges  through  the  external  ring,  and  thence  may  descend 
into  the  scrotum.  This  variety  is  called  an  oblique  inguinal 
hernia.*  If  the  intestine  stops  within  the  inguinal  canal,  it 

*  A  hernia  is  sometimes  called  external  or  internal,  according  to  the  relation 
of  the  protrusion  to  the  deep  epigastric  artery:  thus,  an  oblique  inguinal  hernia  which 
first  protrudes  through  the  inner  ring  is  called  an  external  hernia,  and  vice  -versa. 


ANATOMY  OF  PARTS  CONCERNED  IN  HERNIA.       369 

is  called  an  incomplete  inguinal  hernia ;  if,  however,  the  pro- 
trusion has  emerged  through  the  external  ring,  it  is  called  a  com- 
plete inguinal  hernia  ;  and,  lastly,  if  it  descends  into  the  scrotum, 
it  is  called  a  scrotal  hernia. 

DIRECT  INGOT-  The  intestine,  however,  does  not  always  escape 
NAL  HERNIA,  through  the  internal  ring.  Sometimes  it  protrudes 

internal  to  the  deep  epigastric  artery  through  a  triangular  weak 
place,  bounded  on  the  inner  side  by  the  rectus,  on  the  outer  side 
by  the  deep  epigastric  artery,  and  below  by  Poupart's  ligament. 
This  space*  is  relatively  weak,  having  in  front  of  it  only  the  fascia 
transversalis  and  the  conjoined  tendon  of  the  internal  oblique  and 
transversalis  ;  moreover,  it  is  situated  immediately  behind  the  ex- 
ternal abdominal  ring.  A  portion  of  intestine  protruding  through 
this  triangle  comes  directly  forwards  through  the  external  ring,  and 
the  hernia  is  then  called  a  direct  inguinal  hernia. 

COVERINGS  OF  A  complete  oblique  inguinal  hernia,  passing  as 

AN  OBLIQUE  IN-  it  does  through  the  same  structures  as  the  testis 
GUINAL  HEBNIA.  ^  j^  f^ai  life.,  receives  the  same  coverings  as 
that  gland ;  they  are : — 

1.  The  skin  and  the  superficial  fascia. 

2.  The  inter  columnar  fascia,  derived  from  the  external  oblique. 

3.  The  cremaster  derived  from  the  internal  oblique  and  transversalis. f 

4.  The  infundibuliform  fascia,  derived  from  the  fascia  transversalis. 

5.  The  subperitoneal  fat,  and  the  peritoneum  which  constitutes  the 
sac. 

An  incomplete  oblique  inguinal  hernia  is  covered  by — 

1 .  The  skin  and  superficial  fascia. 

2.  The  aponeurosis  of  the  external  oblique. 

3.  The  cremaster. 

4.  The  infundibuliform  fascia. 

5.  The  sub  peritoneal  fat  and  the  peritoneum. 

COVERINGS  OF  A  -A-  direct  inguinal  hernia  protrudes  immediately 
DIRECT  INGUINAL  on  the  inner  side  of  the  epigastric  artery  through 
HERNIA.  fae  external  ring ;  and  its  course  forwards  is  mainly 

*  Sometimes  called  Hesselbach's  triangle, 
f  The  cremaeter  muscle  is  absent  in  the  female. 
£  B 


370      ANATOMY  OF  PARTS  CONCERNED  IN  HERNIA. 

prevented  by    the    resistance    of  the    conjoined   tendon.*     This 
hernia  is  covered  by — 

1.  The  skin  and  superficial  fascia. 

2.  The  intereolumnar  fascia. 

3.  The  conjoined  tendon  of  the  internal  oblique  and  transversalis. 

4.  The  fascia  transversalis. 

5.  The  subperitoneal  fat  and  the  peritoneum. 

In  almost  all  cases,  the  immediate  investment  of  the  intestine 
is  the  parietal  layer  of  the  peritoneum.  This  constitutes  the  sac 
of  the  hernia,  'The  opening  of  the  sac,  communicating  with  the 
abdomen,  is  called  its  mouth ;  then  comes  the  narrow,  con- 

FIG.  74. 


VARIETIES  OF  CONGENITAL  INGUINAL  HERNIA,  CONSEQUENT  UPON  SOME  DEFECT  IN  THE 
DEVELOPMENT  OF  THE  SPERMATIC  PORTION  OF  THE  TUNICA  VAGINALIS,  THE 
ARROWS  MARK  THE  PROTRUSION. 

1.  Hernia  in  the  tunica  vaginalis  testis.  3.  Infantile  hernia. 

2.  Hernia  in  the  funicular  portion  of  the  tunica  4.  Encysted  hernia. 


stricted  portion,  or  neck ;  and  lastly,  the  body,  or  expanded  part 
of  the  sac. 

CONGENITAL  Owing  to  the  comparatively  late  descent  of  the 

HERNUE.  testis  in   foetal   life,  it  frequently  happens  that 

either  no  closure,  or  only  a  partial  closure,  takes  place  in  the  vaginal 
portion  of  the  tunica  vaginalis.  Under  these  conditions,  when  a 
protrusion  takes  place,  the  intestine  does  not  push  forwards  a  sac 
derived  from  the  parietal  layer  of  the  peritoneum,  but  it  lies  in  a 

*  In  our  experience  the  weakness  of  the  conjoined  tendon  is,  anatomically  speak- 
ing, the  determining  cause  of  this  form  of  hernia. 


ANATOMY    OF    PARTS    CONCERNED    IN    HERNIA.  371 

sac  formed  by  the  tunica  vaginalis,  which  still  communicates  with 
the  peritoneal  cavity.  These  hernise  are  always  oblique,  and  are 
termed  congenital.*  There  are  four  varieties,  all  of  which  are  the 
result  of,  or  associated  with,  some  congenital  defect.  They  are  as 
follows : — 

1.  Hernia  in  the  tunica  vaginalis  testis. ^-This  occurs  when  a  protru- 
sion of  intestine  takes  place  through  the  narrow  canal  which  persists 
between  the  general  cavity  of  the  peritoneum  and  the  tunica  vaginalis 
testis,  in  consequence  of  the  non-obliteration  of  the  original  communica- 
tion between  them.     In  this  case,  the  intestine  surrounds  the  testis,  and 
the  sac  is  formed  by  the  tunica  vaginalis  testis  (fig.  74.  1.). 

2.  Hernia  in  thefunicular  portion  of  the  tunica  vaginalis  occurs  when 
an  incomplete  closure  of  the  tunica   vaginalis  takes  place  immediately 
above  the  testis ;  the  canal  above  it  being  still  unclosed  and  communi- 
cating with  the  peritoneal  cavity.     The  sac  is  formed  by  the  original 
pouch  of  the  peritoneum  in  the  descent  of  the  testis,  although  shut  off 
from  the  tunica  vaginalis  testis  by  a  thin  septum  (fig.  2). 

3.  Infantile  hernia  is  rare,  and  occurs  when  the  original  peritoneal 
canal  is  occluded  at  the  inner  ring,  so  that  the  tunica  vaginalis  testis 
reaches  up  as  high  as  the  canal,  or  even  as  far  as  the  internal  ring.     The 
intestine  in  this  variety  protrudes  a  sac  through  the  inner  ring,  but  behind 
this  abnormal  extension  of  the  tunica  vaginalis  ;  so  that  in  front  of  the 
hernia  there  are  three  layers  of  peritoneum  :  two  formed  by  the  tunica 
vaginalis,  the  third  by  the  sac  (fig.  3). 

4.  Encysted  hernia  is  still  rarer  than  the  preceding,  and  may  occur 
in  those  cases  in  which  the  closing  septum  at  the  internal  ring  is  so  thin 
that  an    advancing  hernia    pushes  before  it  this  thin  stratum  (which 
forms  its  sac)  as  a  diverticulum  into  an  unclosed  tunica  vaginalis '(fig.  4). 

POSITION  OF  The  spermatic  cord  is  generally  situated  behind 

SPERMATIC  COED.  an^  ^o  foe  outer  side  of  a  hernial  sac.  In  some 
cases,  however,  the  hernia  separates  the  constituents  of  the  cord, 
so  that  one  or  other  of  these  comes  to  lie  in  front  of  the  protrusion. 

SEAT  OF  The  stricture  may  be  seated  either  at  the  ex- 

STBICTCBE.  ternal  ring,  the  internal  ring,  at  any  intermediate 

*  The  term  congenital  applied  to  this  form  of  hernia  is  apt  to  suggest  the  idea 
that  it  occurs  at  birth.  But  this  is  not  of  necessity  so.  Although  the  state  of  parts 
favourable  to  its  occurrence  exists  at  birth,  the  hernia  itself  may  not  take  place  till 
many  years  afterwards — in  fact,  at  any  period  of  life. 

B   B   2 


372       ANATOMY  OP  PARTS  CONCERNED  IN  HERNIA. 

part  between  these,  or  at  the  neck  of  the  sac.  Sometimes  there 
is  a  double  stricture,  one  at  the  external  ring,  the  other  at  the 
internal. 

As  stated,  the  stricture  may  be  caused  by  the  neck  of  the  sac, 
independently  of  the  parts  outside  it ;  for  the  peritoneum  may 
become  thickened  and  indurated,  and  sufficiently  unyielding  to 
strangulate  the  protruded  intestine.  The  strangulation  in  a  con- 
genital hernia  is  nearly  always  caused  by  the  neck  of  the  sac  itself. 

In  dividing  the  stricture,  the  surgeon  should,  in  all  cases, 
adhere  to  the  golden  rale  laid  down  by  Sir  Astley  Cooper — namely, 
to  divide  it  directly  upwards.  In  this  direction,  there  is  the  least 
likelihood  of  wounding  the  deep  epigastric  artery. 

CHANGES  PRO-  Whoever  has  the  opportunity  of  dissecting  an 
DUCED  BY  AN  OLD  old  hernia,  of  some  size,  will  observe  that  the 
AND  LARGE  obliquity  of  the  inguinal  canal  is  destroyed.  The 

constant  dragging  of  the  protruded  viscera  upon 
the  inner  margin  of  the  internal  ring  gradually  approximates 
the  internal  ring  to  the  external,  so  that  at  last  the  one  gets 
quite  behind  the  other,  and  there  is  a  direct  opening  into  the 
abdomen.  But  the  position  of  the  deep  epigastric  artery  with 
regard  to  the  sac  remains  unaltered.  It  is  still  on  the  inner  side 
of  the  neck  of  the  sac. 

In  hernise  of  long  standing,  all  its  coverings  undergo  a  change. 
They  become  thickened  and  hypertrophied,  and  so  altered  from 
what  they  once  were  that  they  scarcely  look  like  the  same  parts. 

D  Expose  the  contents  of  the  abdomen,  by  an  in- 

cision from  the  ensiform  cartilage  to  the  pubes  a 
little  to  the  left  side  of  the  linea  alba,  so  as  to  preserve  a  ligament, 
ligamentum  teres,  which  passes  from  the  umbilicus  to  the  liver, 
and  also  a  cord,  the  urachus,  which  ascends  in  the  middle  line 
from  the  bladder  to  the  umbilicus ;  then  make  another  incision 
transversely  on  a  level  with  the  umbilicus,  and  turn  the  flaps 
outwards. 

TT  Behind  the  linea  alba,  the  peritoneum  is  raised 

into  a  fold  by  a  fibrous  cord,  passing  from  the 


POSITION    OF    ABDOMINAL    VISCERA.  373 

bladder  to  the  umbilicus ;  this  is  the  urachus,  which  in  foetal 
life  is  a  tube  connecting  the  bladder  with  the  allantois.  On 
either  side  of  the  urachus  are  two  other  folds  inclosing  cords 
which  ascend  obliquely  towards  the  umbilicus :  these  are  the  im- 
pervious remains  of  the  hypogastric  arteries. 

Take  now  a  survey  of  the  viscera  before  they  are  disturbed  from 
their  relative  positions. 

WHAT  is  SEEN  In  the  right  hypochondrmm  the  liver  is  seen 

ON  OPENING  THE  projecting  more  or  less  below  the  cartilages  of  the 
ABOOMEN.  rifeS)  and  the  fundus  of  the  gall-bladder  below  the 

edge  of  the  liver,  near  the  end  of  the  ninth  costal  cartilage.  In  the 
left  hypochondrium  is  seen  more  or  less  of  the  stomach  according 
to  its  distension.  Across  the  umbilical  region  extends  a  broad  fold 
of  the  peritoneum  containing  fat,  the  great  omentum,  which 
descends  from  the  lower  curvature  of  the  stomach,  forming 
a  curtain  over  the  convolutions  of  the  small  intestine.  The 
breadth  of  this  fold  varies ;  sometimes  being  so  shrunk  and 
crumpled  as  to  be  scarcely  visible.  The  lower  part  of  the  abdomen 
and  part  of  the  pelvis  are  occupied  by  the  small  intestine.  The 
urinary  bladder  is  not  apparent,  unless  distended  sufficiently  to 
rise  out  of  the  pelvis.  In  the  right  iliac  fossa  is  the  caput  coli, 
the  commencement  of  the  large  intestine ;  but  the  ascending  part 
of  the  large  intestine  in  the  right  lumbar  region,  and  the  descend- 
ing part  of  it  in  the  left,  are  not  visible  unless  distended :  they  lie 
contracted  at  the  back  of  the  abdomen.  Such  are  the  viscera 
usually  seen  on  opening  the  abdomen  ;  but  a  certain  latitude  is  <to 
be  allowed,  as  sometimes  more  of  one  organ  is  seen  and  less  of 
another,  according  as  this  or  that  is  distended  or  hypertrophied. 
Much  also  depends  upon  the  .amount  of  pressure  which  the  ribs 
have  undergone  during  life. 

PABTICULAB  The  position  of  each  viscus  should  now  be  ex- 

POSITION  OF  amined  separately,  and  first  that  of  the  stomach. 

The  stomach  is  irregularly  conical  in  shape.  Its 

THE  STOMACH.  great  end  is  situated  in  the  left  hypochondrium  ; 
its  narrow  or  pyloric  end  extends  obliquely  across  the  epigastrium 
into  the  right  hypochondrium,  where  it  is  overlapped  by  the  liver. 


374  POSITION    OF   ABDOMINAL   VISCERA. 

The  relative  position  and  size  of  the  stomach  vary  according  to  the 
amount  of  distension  ;  when  much  distended,  the  anterior  surface, 
owing  to  the  greater  mobility  of  the  great  curve  and  the  pyloric  end 
of  the  stomach,  is  turned  upwards,  and  the  lower  border,  forwards. 
The  following  peritoneal  folds  are  attached  to  the  stomach  :  1.  the 
great  omentum  already  described  ;  2.  the  gastro-hepatic  or  lesser 
omentum,  which  connects  the  lesser  curve  of  the  stomach  with  the 
transverse  fissure  of  the  liver  ;  and  3.  the  gastro-splenic  omentum, 
which  connects  the  great  end  of  the  stomach  with  the  spleen. 

-~  The  first  part  of  the  intestinal  canal  is  termed 

intestinum  duodenum,  because  it  is  about  the 
breadth  of  twelve  fingers.  Commencing  at  the  pyloric  end  of  the 
stomach,  the  duodenum  ascends  as  high  as  the  neck  of  the  gall- 
bladder ;  then  turning  downwards  it  passes  in  front  of  the  right 
kidney  ;  lastly,  making  another  bend,  it  crosses  the  spine  obliquely 
towards  the  left  side  of  the  second  lumbar  vertebra.  Here  the 
intestinum  jejunum  begins,  and  this  part  of  the  canal  may  be  seen 
by  raising  the  transverse  colon.  Thus  the  duodenum  describes 
a  kind  of  horse-shoe  curve,  of  which  the  concavity  is  towards  the 
left,  and  embraces  the  large  end  or  head  of  the  pancreas.  For 
convenience  of  description  the  duodenum  is  divided  into  an 
ascending,  a  descending,  and  a  transverse  portion.  The  first  is 
completely  surrounded  by  a  peritoneal  covering ;  the  second  and 
third  are  only  covered  by  peritoneum  in  front,  and  are  fixed  to 
the  back  of  the  abdomen.  The  relative  anatomy  of  the  duodenum 
will  be  more  fully  seen  hereafter. 

JEJUNUM  AND  Pursuing  its  course  from  the  left  side  of  the 

ILEUM.  second  lumbar  vertebra,  the  intestinal  canal  forms 

a  number  of  convolutions,  which  are  loosely  connected  to  the  spine 
by  a  broad  peritoneal  fold  termed  the  mesentery.  Of  these  con- 
volutions, the  upper  two-fifths  constitute  the  intestinum  jejunum ; 
the  lower  three-fifths,  the  intestinum  ileum.  This  is  an  arbitrary 
division.  There  is  no  definite  limit :  the  character  of  the  bowel 
gradually  changes — that  is,  it  becomes  less  vascular,  has  fewer 
folds  of  the  lining  membrane,  and  its  coats  are  therefore  less  sub- 
stantial to  the  feel. 


POSITION    OF   ABDOMINAL    VISCEKA. 


375 


COMMENCE- 
MENT OF  LAEGE 
INTESTINE. 


In  the  right  iliac  fossa,  the  small  intestine 
opens  into  the  left  side  of  the  colon,  which  is 
easily  recognised  *  by  its  sacculated  appearance  : 
here  the  large  intestine  begins :  here  is  the  ilio-cascal  valve 
(fig.  75).  Immediately  below  the  junction,  the  large  intestine  is 
expanded  into  a  blind  pouch,  called  the  ccecum  or  caput  coli. 
Into  the  back  part  of  this  pouch  opens  a  little  tube  closed  at  the 
other  end,  called  the  appendix  vermiformis.  This  tube  is  gene- 
rally three  inches  long,  about  as  thick  as  a  large  earthworm,  and 

FIG.  75. 


1.  Heum. 

2.  Csecum  or  caput  coll. 


3.  Appendix    vermi- 
form is. 


SECTION    THROUGH    THE   JUNCTION   OP  THE   LABGE   AND   SMALL     INTESTINE    TO   SHOW   THE 
ILIO-OZECAL   VALVE   AND   APPENDIX   VERMIFOBMIS. 

is  either  coiled  up  behind  the  ca3cum,  or  connected  to  it  by  a 
peritoneal  fold,  so  as  to  hang  loose  in  the  pelvis.  The  commence 
ment  of  the  large  intestine  is  generally  confined  by  the  peri- 
toneum to  the  iliac  fossa,  in  which  it  lies.*  Tracing  it  from  this 
point,  it  ascends  through  the  right  lumbar  region  in  front  of  the 
right  kidney  as  high  as  the  under  surface  of  the  liver,  where  it 

*  But  this  is  not  invariably  so.  The  bowel  is,  in  some  subjects,  connected  to  the 
fossa  by  a  fold  of  peritoneum  or  a  meso-ccecum.  I  have  seen  this  fold  sufficiently 
loose  to  allow  the  caput  coli  to  travel  over  to  the  left  iliac  fossa. 


376 


POSITION   OF    ABDOMINAL   VISCEEA. 


makes  a  bend — the  hepatic  flexure — and  crosses  the  umbilical 
region  towards  the  left  side.  Having  reached  the  lower  border 
of  the  spleen,  it  makes  another  bend  downwards,  forming  the  sple- 
nic flexure  of  the  colon  ;*  thence  it  descends  in  front  of  the  left 
kidneyf  through  the  left  lumbar  region  into  the  left  iliac  fossa, 
where  it  curves  like  the  letter  S.  These  successive  portions  of  the 
large  intestine  are  termed,  respectively,  the  ascending,  transverse, 
descending,  and  sigmoid  parts  of  its  course.  Lastly,  the  bowel 
enters  the  pelvis  on  the  left  side  of  the  sacrum,  and  here  takes  the 
name  of  rectum.  This  term,  so  far  as  concerns  the  human  subject, 
is  misapplied ;  the  canal  runs  anything  but  a  straight  course 
through  the  pelvis,  since  it  curves  to  adapt  itself  to  the  sacrum. 

FIG.  76. 


RELATIVE    POSITION   OF   THE    KIDNEYS   AND   THE    LARGE    INTESTINE    SEEN 
FEOM    BEHIND. 


L.  K.  Left  kidney,  crossed  obliquely  by  the  last 

dorsal  artery  and  nerve. 
R.  K.  Bight  kidney. 


A.  c.  Ascending  colon 
D.  c.  Descending  colon. 


Looking  at  the  entire  course  of  the  colon,  observe  that  it  forms 
an  arch,  of  which  the  concavity  embraces  the  convolutions  of  the 
small  intestines. 

*  This  transverse  part  of  the  colon,  in  some  instances,  makes  a  coil  behind  the 
stomach  to  the  diaphragm ;  such  a  state  of  things,  when  the  bowel  happens  to  be  dis- 
tended, is  apt  to  give  rise  to  symptoms  of  diseased  heart.  See  some  observations  in 
point  by  Dr.  Copland,  in  '  Lond.  Med.  Gaz.'  1847,  vol.  v.  p.  660. 

f  The  contiguity  of  the  ascending  and  descending  colon  to  the  right  and  left  kid- 
ney respectively,  explains  the  occasional  bursting  of  renal  abscesses  into  the  intesti- 
nal canal. 


POSITION    OP   ABDOMINAL   VISCEEA.  377 


LENGTH  OF  THE  1^e  small  intestine,  including  the  duodenum, 
ALIMENTAET  varies  from  sixteen  to  twenty-four  feet  in  length, 

CANAL.  and  the  large  intestine  from  five  feet  to  five  feet 

and  a  half;  these  measurements  are  subject  to  some  variation 
according  to  the  height  of  the  individual.  In  round  numbers,  the 
small  and  large  intestines  are  from  five  to  six  times  the  length  of 
the  body, 

SITUATION  OF  The  liver  occupies  the^  whole  of-  the  right  hypo- 

THE  LIVEB.  chondrium,  and  extends  over  the  epigastric  region 

more  or  less  into  the  left.  Unless  the  individual  be  very  corpu- 
lent, we  can  ascertain  during  life  the  extent  to  which  the  liver  pro- 
jects below  the  costal  cartilages,  and  the  general  dimensions  of 
the  organ  may  be  tolerably  well  told  by  percussion.  Its  anterior 
border  is  sharp  and  thin  ;  its  posterior  is  broad  and  connected  to 
the  diaphragm  by  peritoneal  ligaments.  Its  upper  surface  ascends 
as  high  as  the  fifth  intercostal  space  ;  its  under  surface  overlies 
part  of  the  stomach,  of  the  duodenum,  of  the  right  kidney,  of  the 
transverse  colon,  and  of  the  supra-renal  capsule  ;  its  upper  surface 
is  convex,  and  accurately  adapted  to  the  arch  of  the  diaphragm. 
To  this  muscle  the  liver  is  connected  by  folds  of  peritoneum,  called 
ligaments.  One  of  these,  nearly  longitudinal  in  direction,  and 
called  the  suspensory,  or,  from  its  shape,  the  falciform  ligament, 
is  situated  a  little  to  the  right  of  the  mesial  line.  The  lower  and 
free  edge  of  it  contains  the  impervious  remains  of  the  umbilical 
vein,  called  the  round  ligament.  The  suspensory  ligament,  traced 
backwards,  leads  to  another  broad  fold  extending  horizontally  from 
the  diaphragm  to  the  posterior  border  of  the  liver  ;  this  Consti- 
tutes the  lateral  ligament,  right  or  left,  according  as  we  trace  it  on 
one  or  the  other  side  of  the  falciform  ligament. 

The  junction  -of  the  lateral  and  falciform  ligaments  is  described 
by  some  authors  as  the  coronary  ligament. 

SITUATION  OF  THE  The  gall-bladder  is  the  reservoir  for  the  bile, 
GALL-BLADDER.  g^  js  closely  confined  by  the  peritoneum  in  a 
slight  depression  on  the  under  surface  of  the  right  lobe  of  the  liver. 
Its  lower  end  or  fundus  projects  beneath  the  cartilage  of  the  ninth 
rib.  This  is  important  practically.  It  sometimes  happens  that 


378  POSITION   OF   ABDOMINAL    VISCEKA. 

the  gall-bladder,  in  consequence  of  some  obstruction  to  its  duct, 
becomes  unusually  distended,  and  occasions  a  swelling  below  the 
margin  of  the  ribs,  which  might  be  mistaken  for  an  hepatic 
abscess.*  The  close  proximity  of  the  gall-bladder  to  the  duo- 
denum and  the  transverse  colon  explains  the  occasional  evacuation 
of  gall-stones  by  ulceration  into  the  intestinal  canal.f 

SITUATION  OF  The  spleen  is  deeply  situated  in  the  left  hypo- 

THE  SPLEEN.  chondrium,  between  the  stomach  and  the  ninth, 

tenth,  and  eleventh  ribs.  It  is-  placed  nearly  vertically ;  its 
outer  surface  is  smooth  and  convex,  to  correspond  with  the  dia- 
phragm and  the  ribs ;  its  inner  surface,  where  its  great  vessels 
enter,  is  concave  and  connected  to  the  great  end  of  the  stomach  by 
a  peritoneal  fold  called  the  gastro-splenic  omentum.  Generally, 
too,  the  spleen  is  connected  by  a  small  peritoneal  fold,  the  suspen- 
sory ligament,  to  the  under  surface  of  the  diaphragm.^  Below,  the 
spleen  is  in  contact  with  the  kidney  and  the  descending  colon. 

SITUATION  OF  This  is  the  salivary  gland  of  the  abdomen.     It 

THE  PANCREAS.  iies  behind  the.  stomach,  transversely  across  the 
spine,  about  the  level"  of  the  first  lumbar  vertebra.  Its  right  end 
or  head  is  contained  within  the  curve  of  the  duodenum ;  its  left 
end  or  tail  extends  as  far  as  the  spleen.  The  further  connections 
and  relations  of  the  pancreas  cannot  at  this  stage  of  the  dissection 
be  satisfactorily  seen. 

SITUATION  OF  The  kidneys  are  situated  in  the  lumbar  region, 

THE  KIDNEYS.  nearly  opposite  the  two  lower  dorsal  and  the  two 

upper  lumbar  vertebrae ;  the  right,  owing  to  the  size  of  the  liver, 
being  a  little  lower;-  than,  the  left.  They  lie  embedded  in  fat, 
partly  upon  the  quadratus  lumborum,  partly  upon  the  psoas.  In 
contact  with  the  right  kidney,  we  have  the  liver,  the  second 
part  of  the  duodenum,  and  the  ascending  colon ;  in  contact  with 
the  left,  are  the  spleen,  the  end  of  the  pancreas,  and  the  descending 
colon. 

*  See  cases  in  point  recorded  by  Aodral,'  Clin.  Jied.'  torn,  iv.;  and  Graves, '  Dublin 
Hospital  Eeport,'  vol.  iv. 

f  See  preparations  in  the  Museum;  Ser.- 16.  No.  84.. 

J  Every  now  and  then  we  find  in  the  gastro-splenic  omentum  one  or  more  little 
spleens  in  addition  to  the  large  one. 


PERITONEUM.  379 

SITUATION   OF  This  body  is  situated  at  the  top  of  the  kidney. 

THE  SUPBA-BENAL  It  lies  upon  the  crus  of  the  diaphragm.  You  will 
CAPSULE.  gee  fae  right  supra-renal  capsule  by  lifting  up  the 

liver;  the  left,  by  lifting  up  the  spleen  and  the  great  end  of  the 
stomach. 

A  certain  range  of  motion  being  necessary  to 
PEBITONEUM.  .  °  3   .  J 

the  abdominal  viscera,  they  are  provided  with  a 

serous  membrane,  called  the  peritoneum.  This  membrane,  like 
other  serous  membranes,  is  a  closed  sao,  one  part  of  which  lines  the 
containing  cavity,  the  other  is  reflected  over  the  contained  viscera. 
These  are  respectively  termed  the  parietal  and  the  visceral  layers. 
In  the  female,  however,  it  is  not,  strictly  speaking,  a  closed  sac, 
since  it  communicates  with  the  cavity  of  the  uterus  through  the 
Fallopian  tubes.  The  internal  surface  of  the  peritoneum  is  smooth 
and  polished,  and  lined  by  squamous  endothelium:  the  external 
surface,  the  sub-peritoneal  tissue,  is  composed  of  areolar  tissue 
which  connects  the  internal  layer  to  the  invested  viscus  or  ab- 
dominal parietes.  There  is  nothing  between  the  parietal  and  the 
visceral  layers — in  other  words,  inside  the  sac — but  just  sufficient 
moisture  to  lubricate  its  smooth  and  polished  surface.  The  viscera 
are  all,  more  or  less,  outside  the  sac ;  some  lie  altogether  behind  it, 
as  the  pancreas,  kidneys,  and  supra-renal  capsules;  others,  as  the 
lower  parts  of  the  duodenum,  caecum,  ascending  and  descending 
colon,  are  only  partially  covered  by  it ;  while  others^  as  the  stomach, 
liver,  jejunum,  ileum,  and  some  parts  of  the  large  intestine,  are 
completely  invested  by  it:  these  latter  push  the  visceral  layer 
before  them,  and  so  give  rise  to  membranous  folds ;  the  larger  the 
fold,  the  freer  is  the  mobility  of  the  viscus  which  occasions  it. 

COUBSEOFTHE         Now   trace  the    peritoneum    as   a    continuous 
PEBITONEUM.  membrane.    Since  the  peritoneum  is  a  perfect  sac, 

it  matters  not  where  we  begin :  we  must  come  back  to  the  starting- 
point. 

If  a  longitudinal  section  be  made  through  the  viscera  in  the 
middle  of  the  body,  one  can  trace  the  peritoneum  thus — beginning 
at  the  diaphragm,  and  taking,  for  brevity's  sake,  two  layers  at  a 
time  (fig.  77). 


380 


PEEITONEUM. 


From  the  diaphragm  two  layers  of  peritoneum  proceed  to  the 
liver,  forming  its  lateral  ligaments ;  they  .separate  to  inclose  the 
liver,  meet  again  on  its  under  aspect,  and  pass  on,  under  the  name 
of  the  gastro-hepatic  omentum,  to  the  small  curve  of  the  stomach. 
Separating  here,  they  embrace  the  stomach,  and,  meeting  again  at 
FIG.  .7.7.  its  greater  curve,  pass  down  like  a 

curtain  over  the  small  intestine 
to  form  the  great  omentum.  At 
the  lower  margin  of  the  great 
omentum,  they  are  reflected  up- 
wards (so  that  the  great  omentum 
consists  of  four  layers)  to  the-fr-ont 
of  the  transverse  colon,  which  they 
inclose,  and,  after  joining  again  at 
the  back  of  the  colon,  proceed  to 
the  spine,  forming  the  transverse 
meso-coloru  At  this  situation  the 
two  layers  diverge,  the  upper  one 
ascends  in  front  of  the  pancreas, 
and  the  crura  of  the  diaphragm 
to  its  under  surface,  at  which 
point  we  started.* 

The  lower  layer  is  reflected 
from  the  spine  over  the  small  in- 
testine, back  again  to  the  spine,  to 
form  the  mesentery.  From  the  root 
of  the  mesentery  it  descends  into 
the  pelvis,  and  -invests  the  upper 
two-thirds  of  the  rectum.  From 
the  rectum,  in  the  male,  it  is  re- 
flected to  the  posterior  part  of  the 


DIAGRAM  OF  THE  PERITONEUM. 


*  In  foetal  life,  the  ascending  layers  of  the  great  omentum  may  be  traced  back  to 
the  spine  near  the  pancreas ;  and  here  the  layers  diverge  from  each  other.  The  upper 
layer  ascends  in  front  of  the  pancreas  to  the  diaphragm ;  the  lower  layer  proceeds  over 
the  arch  of  the  colon,  and  then  back  to  the  spine,  thus  forming  the  transverse  meso- 
colon.  Its  reflections  afterwards  are  the  same  as  in  the  adult.  As  the  fetus  grows, 
the  great  omentum  becomes  adherent  to  the  arch  of  the  colon. 


PEEITONEUM.  381 

bladder,  forming  the  recto-vesical  pouch,  and  thence  to  the  wall  of 
the  abdomen,  along  which  it  can  be  traced  up  to  the  diaphragm. 
In  the  female,  it  is  reflected  from  the  rectum  on  to  the  posterior 
wall  of  the  vagina  half  an  inch  from  the  uterine  extremity,  consti- 
tuting the  recto-vaginal  pouch,  and  thence  over  all  the  back,  but 
only  about  half-way  down  the  front  of  the  uterus,  to  the  posterior 
wall  of  the  bladder;  after  which  its  reflections  are  the  same  as  in 
the  male. 

Such  is  the  course  of  the  peritoneum  as  seen  in  a  longitudinal 
section,  but  there  are  lateral  reflections  which  cannot  be  seen 
except  in  a  transverse  section :  thus,  from  the  great  end  of 
the  stomach,  two  layers  proceed  to  the  spleen,  forming  the  gastro- 
splenic  omentum  ;  from  the  transverse  meso-colon  it  is  reflected  on 
either  side  over  the  ascending  and  descending  colon. 

The  following  parts  of  the  alimentary  canal  are  only  partially 
covered  by  peritoneum:  namely,  the  descending  and  transverse 
portions  of  the  duodenum,  the  caecum,  the  ascending  and  descend- 
ing colon  (with  exceptional  cases),  and  the  lower  part  of  the  rectum. 

Anatomists  speak  of  the  lesser  cavity  of  the  peritoneum  as  dis- 
tinguished from  the  greater.  This  lesser  cavity,  or  sac  of  the 
omentum,  is  situated  behind  the  stomach  and  the  descending 
layers  of  the  great  omentum.  If  air  be  blown  through  the  foramen 
of  Winslow  (which  is  the  constricted  communication  between  the 
greater  and  lesser  cavities  of  the  peritoneum),  the  lesser  cavity 
becomes  distended ;  it  is  bounded,  in  front,  by  the  lesser  omentum, 
the  stomach,  and  the  descending  layers  of  the  great  omentum ; 
behind,  by  the  ascending  layers  of  the  great  omentum,  the  colon, 
and  the  transverse  meso-colon  ;  above,  by  the  liver. 

FORAMEN  OF  This   foramen   is   the  narrow  circular  opening 

WINSLOW.  between   the  greater   and   lesser   cavities  of  the 

peritoneum,  through  which  the  two  cavities  communicate.  It  is 
situated  behind  the  right  edge  of  the  gastro-hepatic,  or  lesser 
omentum.  By  passing  your  finger  into  it,  you  will  find  the 
foramen  bounded  above  by  the  lobulus  Spigelii  of  the  liver ;  below, 
by  the  commencement  of  the  duodenum  ;  in  front,  by  the  lesser 
omentum ;  and  behind,  by  the  vena  cava  inferior. 


382 


PEEITOISTEUM. 


The  several  folds,  formed  by  the  reflections  of  the  peritoneum, 
which  connect  the  viscera,  either  to  each  other  or  to  the  back  of 
the  abdomen,  have  now  to  be  examined. 

FIG.  78. 


O.P.  Greater  cavity  of 
the  peritoneum. 

L.P.  Leaser  cavity  of 
the  peritoneum. 

A.  Aorta. 


St.  Stomach. 

s.  Spleen. 

v.  Inferior  vena  cava. 

L.  Liver. 


DIAGRAM    OF    A    TRANSVERSE    SECTION   THROUGH    THE    UPPER   PART    OF    THE 
ABDOMINAL    CAVITY    SEEN   FROM    ABOVE. 


MESENTERY. 


This  is  the  fold  which  suspends  the  small  in- 
testine from  the  back  of  the  abdomen.     To  see  it, 
raise  the  great  omentum  and  the  transverse  arch  of  the  colon.    Its 

FIG.  79. 


o.o.  The  great  omen 
turn,  with  its  ca- 
vity. 

i.  Small  intestine. 

A.  Aorta. 


v.  Inferior  vena  cava. 
A.c.  Ascending  colon. 
D.C.  Descending  colon. 
K.  Kidneys. 


DIAGRAM  OF   A   TRANSVERSE  SECTION   THROUGH   THE    LOWER  PART   OF   THE 
ABDOMINAL  CAVITY. 

attached  part  or  root  extends  from  the  left  side  of  the  second 
lumbar  vertebra  obliquely  across  the  spine  to  the  right  iliac  fossa. 
The  loose  part  of  the  mesentery  is  very  broad,  and  curves  like 


PERITONEUM.  383 

a  ruffle,  inclosing  the  small  intestine  from  the  beginning  of  the 
jejunum  to  the  end  of  the  ileum.  We  must  trace  between  its  two 
layers,  the  mesenteric  vessels,  nerves,  glands,  and  lymphatics. 

TRANSVERSE  This  broad  fold  connects  the  transverse  colon  to 

MESO-COLON.  the  back  of  the  abdomen.  It  forms  an  imperfect 

partition  dividing  the  abdomen  into  an  upper  compartment,  con- 
taining the  stomach,  liver,  and  spleen ;  and  a  lower,  containing 
the  convolutions  of  the  small  intestines.  As  regards  the  caecum, 
the  ascending  and  descending  portions  of  the  colon,  they  are,  as  a 
general  rule,  bound  down  by  the  peritoneum  in  their  respective 
situations  (fig.  79).  The  peritoneum  covers  only  two-thirds  or 
thereabouts  of  their  anterior  surface;  their  posterior  surface  is  con- 
nected by  loose  cellular  tissue  to  the  back  of  the  abdomen.*  The 
colon,  ascending  or  descending,  can  therefore  be  opened  in  the 
lumbar  region,  below  the  kidney,  without  injury  to  the  peritoneum : 
a  fact  upon  which  is  founded  the  operation  of  colotomy  for  the 
relief  of  stricture  of  the  rectum. 

GREAT  This  broad  peritoneal  fold  is  composed  of  four 

OMENTUM.  layers,  and  proceeds  from  the  lower  border  of  the 

stomach,  like  a  curtain  over  the  convolutions  of  the  small  intestine. 
Its  thickness  varies  considerably ;  in  thin  subjects  it  is  often 
translucent;  in  corpulent  persons,  on  the  other  hand,  it  is  loaded 
with  fat,  and  contributes  in  great  measure  to  the  size  of  the 
abdomen.  Its  length  also  varies.  In  some  bodies  we  find  it 
extending  low  into  the  pelvis ;  in  others,  small  and  crumpled. 

GASTRO-  This  fold  passes  from  the  transverse  fissure  on 

HEPATIC  OR  the  under  surface  of  the  liver  to  the  upper  curve 

LESSER  OMENTUM.  of  the  stomach>  jt  is  composed  of  two  layers,  and 

between  them  are  the  portal  vein  and  hepatic  artery  with  the  nerves 
going  to  the  liver,  and  the  hepatic  duct  and  lymphatics  coming  from 
it.  The  right  border  of  this  fold  is  free,  while  the  left  passes  on 
to  the  oesophagus.  In  this  fold  the  bile-duct  lies  to  the  right,  the 
hepatic  artery  to' [the  left,  and  the  vena  portse  behind  and  between 

*  In  some  (rare)  cases,  the  ascending  and  descending  colon  (more  commonly  the 
latter)  are  completely  surrounded  by  peritoneum,  and  connected  to  the  lumbar  regions, 
respectively,  by  a  right  and  left  lumbar  meso-colon. 


384 


PERITONEUM. 


them.  If  the  finger  be  introduced  behind  the  right  border,  it 
passes  through  the  foramen  of  Winslow  into  the  lesser  cavity  of  the 
peritoneum. 

GASTBO-  ^his  ^°^  proceeds  from  the  great  end  of  the 

SPLENIC  OMEN-  stomach  to  the  spleen,  and  is  continuous  below 
TUM.  with  the  great  omentum.  It  contains  between  its 

layers  the  branches,  vasa  brevia,  which  proceed  from  the  splenic 
artery  to  the  great  end  of  the  stomach. 

FIG.  80. 


1.  Phrenic. 

2.  Cceliacaxis. 

3.  Superior  mesenteric. 

4.  Supra-renal. 

5.  Renal. 


6.  Spermatic. 

7.  Inferior  mesenteric. 

8.  Lumbar. 

9.  Sacra  media. 


BBANCHES  OF  THE  ABDOMINAL  AOETA. 


The  reflections  of  the  peritoneum  from  the  liver  to  the  abdo- 
minal walls,  forming  its  ligaments,  have  been  described  in  tracing 
the  connections  of  that  organ  (p.  377). 

BEANCHES  OF  Our  next  object  should  be  the  examination  of 

THE  ABDOMINAL        the  arteries  which  supply  the  viscera.     The  aorta 
AoRTA-  enters   the   abdomen   between  the  pillars  of  the 

diaphragm  in  front  of  the  last  dorsal  vertebra,  and  then,  descending 


BRANCHES    OP    THE    ABDOMINAL    AORTA.  385 

a  little  to  the  left  side  of  the  spine,  divides  on  the  fourth  lumbar 
vertebra  into  the  two  common  iliac  arteries.  In  this  course  it 
gives  off  its  branches  in  the  following  order  (fig.  80)  : — 

1 .  The  phrenic,  for  the  supply  of  the  diaphragm. 

2.  The  cceliac  axis,  a  short  thick  trunk  which  immediately 
subdivides  into  three  branches  for  the  supply  of  the  stomach,  the 
liver,  and  the  spleen. 

3.  The  superior  mesenteric,  for  the  supply  of  all  the  small  in- 
testine and  the  upper  half  of  the  large. 

4.  5.  The  supra-renal  and  the  renal  arteries. 

6.  The  spermatic,  for  the  testicles  ;  the  ovarian,  for  the  ovaries. 

7.  The  inferior  mesenteric,  for  the  supply  of  the  lower  half  of 
the  large  intestine. 

8.  The  lumbar,  four  branches  analogous  to  the  intercostals,  for 
the  supply  of  the  back  part  of  the  abdomen. 

9.  The  artena  sacra  media,  which  is  given  off  at  the  bifurca- 
tion of  the  aorta,  supplies  the  fifth  lumbar  artery  and,  running 
down  in  front  of  the  sacrum,  the  lateral  sacral  arteries. 

These  branches  are  to  be  traced  throughout  in 
the  order  most  convenient.  Take  the  coeliac  axis 
first.  To  dissect  this  artery  and  its  branches,  the  liver  must  be 
well  raised,  as  in  fig.  81,  and  the  anterior  layer  of  peritoneum 
removed  from  the  gastro-hepatic  omentum.  A  close  network 
of  very  tough  tissue  surrounds  the  visceral  branches  of  the 
aorta.  This  tissue  consists  almost  entirely  of  plexuses  of  nerves, 
derived  from  the  sympathetic  system,  each  plexus  taking  the  name 
of  the  artery  which  it  surrounds.  Of  these  plexuses,  the  largest 
surrounds  the  cceliac  axis  like  a  ring.  This  is  the  solar  plexus, 
and  is  formed  by  the  junction  of  the  two  semi-lunar  ganglia  (see 
dissection  of  thorax,  p.  147).  From  this,  as  from  a  root,  other 
secondary  plexuses  branch  off,  and  surround  the  following  arteries 
— the  phrenic,  coronary,  hepatic,  splenic,  superior  mesenteric, 
inferior  mesenteric,  and  renal ;  the  plexuses  receiving  the  names  of 
the  arteries  around  which  they  twine.  It  requires  a  lean  subject 
and  much  patience  to  trace  them. 

C  0 


BRANCHES   OF    THE    CCELIAO    AXIS. 


PLAN   OF   THE   BEANOHES    OF  THE    CCELIAC   AXIS. 


C  Coronaria    ventri-  f"  cesophageal. 
culi.  \  gastric. 


CffiLIAC   AXIS 


i 

I  Hepatic 


Splenic 


pyloric.  .  [gastro-epiploica  dextra. 

gastro-duodenalis.   -j  pancreatico-duodenalis 
cystic.  I      superior. 

pancreatic  branches, 
gastro-epiploica  sinistra. 
vasa  brevia  to  stomach. 


C<ELIAC  AXIS 
AND  ITS 

BRANCHES. 


The  coeliac  axis  arises  from  the  front  of  the 
aorta,  between  the  pillars  of  the  diaphragm,  im- 
mediately above  the  upper  border  of  the  pancreas, 
and  to  the  left  of  the  lobulus  Spigelii.  It  is  a  very  thick,  short 
trunk,  which  runs  between  the  two  layers  of  the  lesser  omentum, 
and,  after  a  course  of  about  half  an  inch,  divides  into  three 
branches — the  coronaria  ventriculi,  the  splenic,  and  the  hepatic. 

COBONABIA  The  coronaria  ventriculi^  the  smallest  of  the 

VENTKICTLL  three,   ascends   a   little  to  the  left  towards  the 

cesophageal  end  of  the  stomach,  where  it  gives  off  cesophageal 
branches,  which  inosculate  with  the  cesophageal  branches  of  the 
thoracic  aorta.  It  then  runs  along  the  lesser  curvature  of  the 
stomach  towards  the  pylorus,  and  anastomoses  with  the  pyloric 
branch  of  the  hepatic  artery. 

HEPATIC  The  hepatic  artery  ascends  to  the  right  between 

ABTEBT.  t,ne  layers  of  the  lesser  omentum  to  the  transverse 

fissure  of  the  liver,  where  it  divides  into  two  branches,  right  and 
left,  for  the  supply  of  the  respective  lobes  of  the  liver. 

In  its  course  to  the  liver,  it  lies  to  the  left  of  the  bile-duct, 
and  in  front  of  the  portal  vein ;  all  three  are  contained  in  the 
right  half  of  the  lesser  omentum.  The  hepatic  gives  off — 

a.  The  pyloric,  which  runs  along  the   upper  curve  of  the  stomach 
from  right  to  left,  and  inosculates  with  the  coronaria  ventriculi. 

b.  The  gastro-duodenalis,  passing  behind  the  ascending  portion  of  the 


BLANCHES    OF    THE    CCELIAC    AXIS. 


387 


duodenum,  divides  into  (a)  the  gastro-epiploica  dextra,  which  runs  along 
the  greater  curve  of  the  stomach,  from  right  to  left,  and  anastomoses 
with  the  gastro-epiploica  sinistra  from  the  splenic ;  and  (/3)  the  pancrea- 
tico-duodenalis  superior,  which  runs  down  between  the  head  of  the  pan- 
creas and  the  descending  portion  of  the  duodenum,  and  anastomoses  with 
the  pancreatico-duodenalis  inferior,  a  branch  of  the  superior  mesenteric. 
c.  The  cystic,  commonly  a  branch  of  the  right  hepatic,  divides  into 
two  branches,  one  of  which  ramifies  on  the  under  surface  of  the  gall- 

Fio.  81. 


_  Spleen. 


Descending 
duodenum    . 


Termination 
of  bile-duct. 


Commencement  of  the  intesti- 
num  jejunum. 


DIAGEAM    OF    THE    BRANCHES    OF    THE    CO3UAC   AXIS. 

(Pancreas  in  dotted   outline  behind  the   stomach.) 


1.  Coronaria  ventriculi. 

2.  Splenic  a. 

3.  Hepatic  a. 

4.  Pyloric  a. 


5.  Gastro-duodenalis. 

6.  Gastro-epiploica  sinistra. 

7.  Vasa  brevia. 

8.  Superior  mesenteric  a. 


bladder,  the  other  passes  between  the  liver  and  the  upper  surface  of  the 
gall-bladder. 

The  splenic,  the  largest  of  the  three,  proceeds 
tortuously  towards  the  left  side,  above  its  corre- 
c  c-  2 


SPLENIC 
A  BTBRT. 


388 


VENA    POETJE. 


spending  vein,  along  the  upper  border  of  the  pancreas  to  the  spleen, 
which  it  enters  by  numerous  branches. 

It  gives  off:  1.  Several  small  branches  to  the  pancreas,  pancreaticce 
parvce.  One,  rather  larger  than  the  rest,  which  accompanies  the  pan- 
creatic duct,  is  called  pancreatica  magna.  2.  The  gastro-epiploica 
sinistra,  which  runs  to  the  right  along  the  great  curve  of  the  stomach, 
and  inosculates  with  the  gastro-epiploica  dextra.  3.  Vasa  brevia,  which 
proceed  between  the  layers  of  the  g astro-splenic  omentum,  to  the  great 
end  of  the  stomach,  where  they  communicate  with  branches  from  the 
coronaria  ventriculi,  and  the  gastro-epiploica  sinistra.  4.  The  splenic 
branches  are  five  or  six  in  number,  and  enter  the  fissure  of  the  spleen. 

Thus  the  stomach  is 
supplied  with  blood  by  four 
channels,  which  by  their 
inosculations  form  a  main 
artery  along  its  lesser 
curve,  another  along  its 
greater  ;  from  these,  nu- 
merous branches  are  fur- 
nished to  both  surfaces  of 
the  stomach.  The  artery 
of  the  greater  xwrve  also 
sends  down  numerous  omen- 
tal  branches,  which  form  a 
network  between  the  layers 
of  the  great  omentum. 

VENA  POBTJE  :  The  veins 

ITS  PECULIAEITIES.      which       re- 

turn  the  blood  from  the 
abdominal  portion  •  of  the 
alimentary  canal,  the  pan- 
creas, and  the  spleen,  do 
not  empty  themselves  into 
the  vena  cava  inferior,  but 
all  unite  into  one  large 
vein,  called  the  vena  portce,  which  ramifies  throughout  the  liver, 


DIAGRAM    OF    THE    VKNA    POBT^K. 

(The  arrow  is  introduced  behind  the  free 
border  of  the  lesser  omentum.) 


VENA    PORTSE.  389 

and  secretes  the  bile.  The  trunk  of  the  vena  portse  itself  is 
about  three  inches  long.  Tracing  it  downwards  you  find  that 
it  is  formed  behind  the  great  end  of  the  pancreas,  by  the  con- 
fluence of  the  splenic  and  superior  mesenteric  veins  (fig.  82). 
In  its  passage  to  the  liver,  the  vena  portse  is  accompanied  by 
the  hepatic  artery  and  the  common  bile-duct,  lying  behind  and 
between  them.  At  the  transverse  fissure  of  the  liver  it  divides 
into  two  branches  corresponding  to  the  right  and  left  lobes. 
The  vein  ra-mifies  in  the  substance  of  the  liver  like  an  artery, 
and  is  surrounded,  with  the  branches  of  the  hepatic  artery  and 
duct,  in  a  sheath  of  areolar  or  fibrous  tissue  called  Glisson's  capsule. 
The  vena  portse  may,  then,  be  compared  to  the  stem  of  a  tree,  of 
which  the  roots  arise  in  the  digestive  organs,  and  the  branches 
spread  out  in  the  liver.  After  receiving  the  veins  corresponding  to 
the  branches  of  the  hepatic  artery,  the  vena  portse  returns  its  blood 
into  the  inferior  vena  cava  through  the  venae  cavse  hepaticae. 

The  veins  which  empty  themselves  into  the  vena  portse  have 
no  valves.  Therefore,  if  any  obstruction  arise  in  the  venous 
circulation  through  the  liver,  the  roots  of  the  portal  vein  are  apt 
to  become  congested :  this  is  a  common  cause  of  hsemorrhoids, 
diarrhoea,  hsemorrhage  from  the  bowels,  and  ascites.  Leeches 
applied  to  the  anus  have  been  long  recognised  as  beneficial  in 
congestion  of  the  liver. 

The  hepatic  duct  is  composed  of  two  trunks,  one 
from  the  right  lobe  and  the-  other  from  the  left : 
it  is  soon  joined  by  the  cystic  duct  from  the  gall-bladder.  The 
common  duct,  ductus  communis  choledochus,  thus  formed,  passes 
between  the  two  layers  of  the  lesser  omentum  close  to  its  right 
border,  then  behind  the  first  portion  of  the  duodenum,  and  opens 
obliquely  into  the  back  part  of  the  second  portion,  near  the  junc- 
tion with  the  third.  The  duct  runs  through  the  coats  of  the 
bowel  for  nearly  three-quarters  of  an  inch  (p.  387).  As  the  common 
bile-duct  descends  between  the  layers  of  the  lesser  omentum,  it 
lies  in  front  of  the  vena  portse,  having  the  hepatic  artery  on  its 
left.  The  duct  is  about  three  inches  long,  and  if  distended  would 
be  about  the  size  of  a  crow-quill. 


390 


MESENTERIC   VESSELS. 


DISSECTION. 


The  great  omentum,  with  the  arch  of  the  colon, 
must  now  be  turned  up  over  the  chest,  and  the 
small  intestines  pushed  towards  the  left  side.  Then,  by  removing 
the  anterior  layer  of  the  peritoneum  from  the  mesentery,  we  expose 
the  mode  in  which  the  superior  mesenteric  artery  ramifies  so  as  to 
supply  the  small  intestine.  In  making  this  dissection,  the  mesen- 
teric glands  immediately  attract  notice.  They  lie  in  great 
numbers  between  the  layers  of  the  mesentery,  and  vary  consider- 
ably in  size.  The  fine  tubes,  called  lacteal  vessels,  which  traverse 

FIG.  83. 


1.  Superior  mesenteric  a. 

2.  Colica  media. 

3.  Colica  dextra. 

4.  Ileo-colica. 


5.  Inferior  mesenteric  a. 

6.  Colica  sinistra. 

7.  Arteria  sigmoidea. 

8.  Superior  hsemorrhoidal 


PLAN    OF   THE   MESENTERIC    AKTEEIES,    AND    THEIR    COMMUNICATIONS. 

the  glands,  are  too  thin  and  transparent  to  be  seen  under  ordinary 
circumstances.  But  in  cases  where  sudden  death  has  taken  place 
during  digestion,  they  are  found  distended  with  chyle,  and  can  be 
traced  into  the  glands  from  all  parts  of  the  small  intestine.*  After 
traversing  the  glands,  they  all  eventually  empty  their  contents  into 
the  receptaculum  chyli  (p.  142). 


*  The  arrangement  of  the  chyliferous  vessels  is  well  displayed  in  the  plates  of 
Mascagai. 


MESENTERIC    VESSELS.  391 

SUPERIOR  This  large  artery  arises  from  the  front  of  the 

MESENTEBIC  aorta,  descends  beneath  the  pancreas,  in  front  of 

ABTEBY  AND  the  transverse  part  of  the  duodenum  (p.  387),  and 

INCHES.  then  runs  between  the  layers  of  the  mesentery 

towards  the  right  iliac  fossa,  where  it  terminates  in  branches  for 
the  supply  of  the  caecum.  Thus  it  describes  a  gentle  curve  from 
left  to  right.  It  gives  off  the  following  branches  : — 

1.  The  inferior  pancreatico-duodenal  branch,  which  runs  tip,  within 
the  concavity  of  the  duodenum,  to  inosculate  with  the  superior  pancre- 
atico-duodenal branch  of  the  hepatic.  2.  Vasa  intestini  tennis  of  the 
small  intestine,  from  ten  to  sixteen  in  number,  are  given  off  from  the 
left  or  convex  side  of  the  curve ;  while  from  the  concave  side  come,  3. 
the  ileo-colic ;  4.  the  right  colic ;  and  5.  the  middle  colic  for  the  supply 
of  the  ileum,  caecum,  ascending,  and  transverse  colon,  respectively. 

The  student  should  now  trace  the  branches  to  the  small  intes- 
tine, in  order  to  see  the  series  of  arches  which  they  form  by  their 
mutual  inosculations.  There  are  three  or  four  tiers  of  them, 
each  tier  composed  of  smaller  and  more  numerous  branches  than 
the  preceding.  The  ultimate  branches  ramify  in  circles  round 
the  intestine.  This  circular  arrangement  of  the  vessels  in  the 
coats  of  the  bowel  is  practically  interesting,  because  it  enables 
one  in  almost  all  cases  to  distinguish  the  intestine  from  the 
hernial  sac. 

The  colic  branches  of  the  superior  mesenteric  are  the  ileo-colic,  which 
is  the  continuation  of  the  main  trunk,  and  divides  into  two  branches  ; 
one  supplies  the  lower  part  of  the  ileum,  and  the  other  the  csecum  : — 
the  right  colic,  which  proceeds  towards  the  ascending  colon,  and  the 
middle  colic,  which  ascends  between  the  layers  of  the  meso-colon  to  the 
arch.  They  are  arranged  after  the  same  plan  as  those  of  the  small  in- 
testine :  that  is,  they  inosculate  and  form  a  series  of  arches  which  suc- 
cessively decrease  in  size  and  finally  terminate  in  circles  round  the 
bowel. 

The  superior  mesenteric  vein  joins  the  splenic  behind  the  pan- 
creas, and  forms  the  vena  portse  (p.  388), 


392  MESENTEEIC   VESSELS. 

To  trace  this  artery,  the  small  intestine  must  be 

DISSECTION  OF  »      V        » 

THE  INFEBIOE           drawn  over  towards  the  right  side,  and  the  peri- 
MESENTERIC  toneum  covering  the  artery  removed.     It  is  given 

ARTERY  AND  off  from  the  front  of  the  aorta,  about  two  inches 

above  its  bifurcation.  Descending  towards  the 
left  iliac  fossa,  it  crosses  obliquely  over  the  left  common  iliac 
artery,  passes  between  the  layers  of  the  meso-rectum,  and,  taking 
the  name  of  superior  hcemorrhoidal,  is  finally  distributed  to  the 
upper  part  of  the  rectum.  Its  branches  are : — 

1.  The  colica  sinistra,  which  crosses  behind  the  peritoneum,  over  the 
left  kidney,  and  supplies  the  descending  colon. 

2.  The  sigmoidea,  which  is  distributed  to  the  sigmoid  flexure. 

3.  The  superior  hcemorrhoidal,  which  supplies  the  upper  part  of  the 
rectum,  and  will  be  dissected  with  the  side  view  of  the  pelvis. 

These  branches  of  the  inferior  mesenteric  inosculate  in  the  form 
of  arches,  like  the  colic  branches  of  the  superior  mesenteric.  The 
colica  sinistra,  too,  forms  a  large  arterial  arch  with  the  colica 
media,  so  that  there  is  a  chain  of  arterial  communications  from 
one  end  to  the  other  of  the  intestinal  canal  (fig.  83). 

The  inferior  mesenteric  vein  ascends  nearly  vertically  in  front 
of  the  left  psoas,  and  joins  the  splenic  behind  the  pancreas. 

To  see  the  relations  of  the  duodenum  and  the 
pancreas,  two  ligatures  about  an  inch  apart  should 
be  placed  on  the  upper  end  of  the  jejunum,  and  two  others  at  a 
similar  distance  apart  on  the  lower  end  of  the  sigmoid  flexure  of 
the  colon.  After  the  jejunum  and  the  sigmoid  flexure  have  been 
divided  between  the  ligatures  respectively,  the  small  and  large 
intestines  can  be  removed.  By  turning  up  the  stomach,  we  expose 
the  duodenum  curving  round  the  great  end  of  the  pancreas. 

DUODENUM,  The    duodenum    (p.  387)    commences  at   the 

EELATIONS  OF.  pyloric  end  of  the  stomach,  and  terminates  on 
the  left  side  of  the  second  lumbar  vertebra,  where  the  intestinum 
jejunum  begins.  It  is  divided  into  three  parts,  an  ascending, 
descending,  and  transverse. 

The  first  portion  ascends  obliquely  as  high  as  the  neck  of  the 
gall-bladder ;  then  making  a  sudden  bend,  it  descends  in  front 


DUODENUM  AND  PANCEEAS.  393 

of  the  right  kidney  as  low  as  the  third  lumbar  vertebra.  Lastly, 
making  another  bend,  it  ascends  obliquely  across  the  spine  to  the 
left  side  of  the  second  lumbar  vertebra :  here  the  intestine  takes 
the  name  of  jejunum.  Thus  the  duodenum  describes  a  horse- 
shoe curve,  the  concavity  of  which  is  directed  towards  the  left 
side,  and  embraces  the  head  of  the  pancreas. 

The  first  or  ascending  portion  is  about  two  inches  long,  and 
is  completely  invested  by  peritoneum.  It  is  comparatively  free, 
so  that  the  movements  of  the  stomach  may  not  be  restricted. 
In  front  of  it  are  the  liver  and  gall-bladder.  Behind  it  are  the 
bile-duct  and  the  hepatic  vessels.  The  second  or  descending  por- 
tion lies  behind  the  transverse  colon.  Behind  it  are  the  common 
bile-duct  and  the  pancreatic  duct,  which  empty  themselves  into 
it  either  separately,  or  by  a  common  opening.  The  descending 
portion  is  covered  with  peritoneum  only  on  its  anterior  surface. 
The  third  or  transverse  portion  is  about  four  inches  long,  is 
situated  behind  the  transverse  meso-colon,  just  above  the  mesen- 
tery, and  below  the  superior  mesenteric  artery  and  the  pancreas. 
It  lies  upon  the  aorta  and  inferior  vena  cava.  This  portion,  like 
the  second,  is  only  covered  in  front  by  peritoneum.  Notice  how 
firmly  the  duodenum  is  braced  up  on  the  left  side  of  the  second 
lumbar  vertebra ;  and  how  the  jejunum  begins  here  by  an  abrupt 
downward  bend. 

PANCEEAS,  This  large  gland   is  situated  immediately  be- 

EELATIONS  OF.  m'nd  the  stomach  (p.  378.)  It  is  of  an  elongated 
form,  and  of  pinkish-white  colour.  It  is  placed  transversely  across 
the  spine ;  its  larger  end,  or  head,  is  embraced  by  the  duodenum  ; 
its  lesser  end,  or  tail,  is  in  contact  with  the  spleen.  The  splenic 
artery  and  vein  run  along  the  upper  border  of  the  gland,  and 
above  it  is  the  coeliac  axis ;  the  lower  border  is  in  relation  with 
the  transverse  portion  of  the  duodenum,  from  which  it  is  sepa- 
rated by  the  superior  mesenteric  vessels.  Posteriorly,  the  pan- 
creas rests  upon  the  inferior  vena  cava,  the  left  kidney,  the  left 
supra-renal  capsule,  the  commencement  of  the  vena  portse,  the 
aorta,  the  crura  of  the  diaphragm,  the  superior  mesenteric 
vessels  and  the  inferior  mesenteric  vein.  Its  duct  runs  from  left 


394  KIDNEYS. 

to  right,  near  the  lower  border  and  anterior  surface  of  the  gland, 
and  empties  itself  into  the  back  part  of  the  descending  portion 
of  the  duodenum,  conjointly  with,  or  close  to,  the  opening  of  the 
common  bile-duct.  It  receives  numerous  branches  from  the 
splenic  artery,  which  runs  along  its  upper  border ;  some  from  the 
superior  mesenteric,  which  lies  immediately  beneath  it,  and  others 
from  the  gastro-duodenalis. 

The  liver,  stomach,  duodenum,  pancreas,  and 
spleen  should  now  be  collectively  removed.  For 
this  purpose  it  is  necessary  to  cut  through  the  ligaments  of  the 
liver,  the  vense  cavse  hepaticse,  and  the  branches  of  the  coeliac 
axis.  These  viscera,  with  the  remainder  of  the  intestinal  canal, 
should  be  macerated  in  water,  while  you  examine  all  that  is  to 
be  seen  at  the  back  of  the  abdomen  :  namely,  the  deep-seated 
muscles,  the  aorta,  the  inferior  vena  cava,  the  kidneys,  the  lumbar 
plexus  of  nerves,  and  the  sympathetic  nerve. 

KIDNEYS  AND  The  kidneys  are  situated  in  the  lumbar  region, 

URETER,  EELA-  behind  the  peritoneum,  one  on  each  side  of  the 
TIONS  or.  spine.  They  lie  embedded  in  more  or  less  fat,  on 

the  quadratus  lumborum,  the  psoas,  and  the  crura  of  the  diaphragm. 
The  right  is  somewhat  the  lower  of  the  two.  Surmounting  each 
is  a  small  body,  called  the  supra-renal  capsule.  The  excretory 
duct  of  the  kidney,  the  ureter,  descends  almost  vertically  on  the 
psoas  muscle,  enters  the  pelvis  over  the  division  of  the  common 
iliac  artery,  and  empties  itself  into  the  lower  part  of  the  bladder 
after  running  obliquely  through  its  coats.  The  right  kidney  is  in 
contact,  above,  with  the  under  surface  of  the  liver,  and  its  upper 
end  reaches  as  high  as  the  lower  border  of  the  eleventh  rib ;  the 
left  is  in  contact  above  with  the  spleen,  and  reaches  to  the  level  of 
the  upper  border  of  the  eleventh  rib. 

In  front  of  the  right  kidney  are  the  liver,  the  ascending  colon, 
the  descending  portion  of  the  duodenum,  and  the  colica  dextra 
artery ;  in  front  of  the  left,  the  descending  colon,  part  of  the 
spleen,  the  pancreas,  and  the  colica  sinistra  artery.  This  explains 
how  it  is  that  a  renal  abscess  or  calculus  is  sometimes  evacuated  by 
the  rectum. 


DIAPHRAGM. 


395 


The  outer  border  of  the  kidney  is  convex,  the  inner  concave, 
and  presents  a  notch,  the  hilus,  for  the  entrance  of  the  vessels 
and  duct,  which  have  the  following  relations : — anteriorly  is  the 
renal  vein,  posteriorly  is  the  ureter,  the  renal  artery  being  between 
them. 

The  kidneys  and  supra-renal  capsules  must  be 
removed  and  reserved  for  further  examination. 

The  semilunar  ganglia,  two  in  number,  are 
situated  one  on  each  side  of  the  creliac  axis,  in  the 
neighbourhood  of  the  supra-renal  bodies ;  that  on  the  right  side 
will  be  found  lying  under  the  vena  cava  inferior.  Their  filaments 

FIG.  84. 


DISSECTION. 

SEMILTJNAB 
GANGLIA.. 


1.  Aorta  passing  be- 

tween the  crura. 

2.  Opening  for  ceso- 

phagus. 

3.  Opening  for  vena 

cava. 


4.  Quadrat  us    lum- 

borum. 

5.  Psoas  magnua. 

The  dark  arches 
above  the  quad- 
ratus  and  psoas 
are  the  '  arcu- 
ate ligaments.' 


DIAPHRAGM. 


DIAGRAM    OF   THE   DIAPHBAGM,    THE  OPENINGS    IN    IT,    AND    THE   PHRENIC   ARTKRIE8. 

are  distributed  to  the  supra-renal  and  renal  plexuses,  and  to  the 
plexuses  which  surround  the  branches  of  the  abdominal  aorta. 
Above,  each  ganglion  receives  the  great  splanchnic  nerve  (p.  147). 
This  is  a  partly  muscular  and  partly  tendinous 
arch,  so  constructed  as  to  form  a  complete  movable 
partition  between  the  chest  and  the  abdomen  ;  a  floor  for  the  one, 
and  a  roof  for  the  other.  Its  upper  or  thoracic  surface  is  convex  ; 
its  lower  or  abdominal,  concave.  On  removing  its  peritoneal 
covering,  we  observe  a  broad  tendon  in  the  centre,  and  that 
muscular  fibres  converge  to  it  from  all  sides  (fig.  84).  The  dia- 
phragm arises,  1.  From  the  ensiform  cartilage ;  2.  From  the  inner 


396  DIAPHRAGM. 

surfaces  of  the  cartilages  of  the  six  lower  ribs  by  as  many 
digitations,  which  correspond  with  those  of  the  transversalis ; 
3.  From  two  thin  tendinous  arches,  called,  respectively,  the  liga- 
menta  arcuata,  externum  and  internum  (the  external  arch 
extends  from  the  last  rib  to  the  transverse  process  of  the  first 
lumbar  vertebra,  and  arches  over  the  quadratus  lumborum ;  the 
internal  passes  from  the  transverse  process  of  the  first  lumbar 
vertebra  to  the  body  of  the  same  vertebra,  and  arches  over  the 
psoas) ;  and  4.  From  the  front  of  the  bodies  of  the  lumbar  vertebrae 
by  two  elongated  bundles,  called  the  crura  of  the  diaphragm. 
Both  erura  have  tendinous  origins ;  the  right  crus  is,  however,  a 
little  longer  than  the  left ;  the  former  arises  from  first,  second, 
and  third  lumbar  vertebrae  and  their  intervening  cartilages,  the 
left  does  not  descend  so  low  by  one  vertebra.  The  inner  fibres 
of  each  crus  decussate  ;  those  of  the  right  being  the  more  anterior. 
In  their  decussation  the  fibres  separate  the  aortic  from  the  oeso- 
phageal  openings.  Between  the  two  crura  the  aorta  enters  the 
abdomen. 

From  these  various  origins  the  fibres  ascend,  at  first  nearly 
vertically,  and  then  all  arch  inwards,  and  converge  to  be  inserted 
into  the  central  tendon. 

The  central  tendon  is  nearly  the  highest  part  of  the  diaphragm. 
It  presents  a  white  glistening  surface,  owing  to  the  crossing  of  its 
tendinous  fibres ;  and  its  shape  may  be  compared  to  that  of  a 
trefoil  leaf.  The  chief  point  of  interest  about  the  tendon  is  that, 
in  consequence  of  its  connections  with  the  pericardium,  below 
which  it  lies  (p,  134),  it  is  always  maintained  nearly  on  the  same 
level ;  so  that  it  helps  to  support  the  heart,  and  serves  as  a  fixed 
point  for  the  insertion  of  the  muscular  fibres  of  the  diaphragm. 

OPENINGS  m  There  are  three  large  openings  in  the  diaphragm 

THE  DIAPHRAGM.  for  £he  transmission  of  the  aorta,  the  oesophagus, 
and  the  inferior  vena  cava,  respectively.  The  aortic  opening  lies 
between  the  crura  in  front  of  the  spine ;  it  transmits,  also,  the 
vena  azygos  and  the  thoracic  duct,  both  of  which  lie  rather  to  the 
right  side  of  the  aorta.  Trace  the  crura  upwards,  and  observe 
that  the  inner  fibres  of  each  cross  each  other  in  front  of  the  aorta, 


DIAPHRAGM. 


397 


FIG.  85. 


somewhat  like  the  letter  X.*  Above  the  decussation,  and  a  little 
to  the  left  of  it,  is  the  cesophageal  opening ;  this  is  oval  and 
entirely  muscular,  and  transmits  the  oesophagus  and  the  pneumo- 
gastric  nerves.  The  opening  for  the  vena,  cava  (foramen 
quadratuTn)  is  situated  in 
the  highest  part  of  the  cen- 
tral tendon,  rather  to  the 
right  of  the  middle  line. 
Observe  that  the  vein  is 
intimately  connected  to  its 
margin,  and  kept  perma- 
nently open.  Lastly,  there 
pass  through  the  crus,  on 
each  side,  the  sympathetic 
and  the  greater  and  lesser 
splanchnic  nerves.  The 
arch  of  the  diaphragm,  in 
expiration,  extends  about 
as  high  as  the  fifth  rib  on 

the  right  side,  and  the  sixth 

0  '  (The  dotted  lines  show  the  amount  of  descent 

rib  on  the  left.  ^  contraction.) 

The  nerves  of  the  dia- 
phragm are  the  phrenic  (p.  1 32),  and  the  five  or  six  lower  inter- 
costal nerves.  The  diaphragm  also  receives  minute  filaments 
from  the  diaphragmatic  plexus,  which  comes  from  the  semilunar 
ganglia.  On  its  under  surface  on  the  right  side,  close  to  the 
supra-renal  capsule,  the  plexus  joins  some  branches  of  the  right 
phrenic  nerve,  at  which  spot  there  is  a  small  ganglion  (ganglion 
diaphragmaticum),  from  which  filaments  are  given  off  to  the 
liver,  vena  cava  and  supra-renal  capsule.  It  is  absent  on  the  left 
side.  Its  blood-vessels  are  the  two  phrenic,  derived  from  the 
aorta,  the  internal  mammary  (p.  121),  and  the  lower  intercostal. 

FUNCTION  OF  The  diaphragm  is  the  great  muscle  concerned 

THE  DIAPHRAGM.       in  inspiration.     It  may  be  said  with  Haller,  that  it 


DIAPHRAGM    FROM    ITS   UPPER    SURFACE. 


*  This  declaration  is  not  always  complete.     But  the  right  crus  always  crosses 
more  or  less  over  the  left,  so  that  the  crura  are  never  strictly  parallel. 


398  DIAPHKAGM. 

is  *  musculus  post  cor  nobilissimus.'  During  inspiration  the  mus- 
cular sides  of  the  diaphragm  contract,  and  become  less  arched 
(as  shown  by  the  dotted  line  in  fig.  85) ;  the  floor  of  the  chest  sinks 
in  consequence,  and  more  room  is  made  for  the  expansion  of  the 
lungs.  During  expiration  the  diaphragm  relaxes,  and  the  air  is 
expelled,  partly  by  the  elasticity  of  the  lungs  and  the  thoracic 
walls,  partly  by  muscular  action.  This  alternate  sinking  and 
rising  of  the  diaphragm  constitutes  a  chief  part  of  the  mechanism 
of  breathing.  But  the  diaphragm  conduces  to  the  performance  of 
many  other  functions.  Acting  in  concert  with  the  abdominal 
muscles,  it  assists  in  the  expulsion  of  the  faeces  and  the  urine,  also 
in  parturition  and  in  vomiting  :  for  in  all  these  operations  we  first 
take  in  a  deep  breath,  that  the  diaphragm  may  be  in  a  state  of 
contraction,  and  so  form  a  resisting  surface,  against  which  the 
viscera  may  be  compressed  by  the  abdominal  muscles.  Moreover, 
by  its  rapid  or  spasmodic  contractions  it  is  one  of  the  chief  agents 
concerned  in  laughing,  sneezing,  coughing,  hiccough. 

^  The  muscles   and  nerves  at  the  back   of  the 

DISSECTION. 

abdomen  must  be  carefully  cleaned ;  also,  the 
abdominal  aorta,  and  vena  cava  inferior  in  front  of  the  spine,  with- 
out injuring  the  sympathetic  nerves,  situated  on  each  side  of  the 
bodies  of  the  vertebras.  The  sheath  which  invests  the  psoas  should 
be  examined,  and  the  branches  of  the  lumbar  plexus,  preserved  as 
they  emerge  from  the  outer  part  of  the  muscle. 

The  sheath  of  the  psoas  is  attached  to  the  sides  of  the  vertebrae, 
the  brim  of  the  pelvis,  and  above  to  the  ligamentum  arcuatum 
internum.  It  is  this  sheath  which  determines  the  ordinary  course 
of  psoas  abscess  :  namely,  beneath  the  crural  arch  into  the  upper 
part  of  the  thigh ;  for  it  is  a  rare  exception  when  the  matter  travels 
into  the  pelvis. 

M  This  long  muscle  arises  by  five  muscular  fasciculi 

from  the  transverse  processes  of  all  the  lumbar 
vertebrae,  also  from  the  bodies  of  the  last  dorsal,  and  all  the 
lumbar  vertebrae  and  their  intervening  fibre-cartilages ;  but  only 
from  the  projecting  borders  of  the  bodies,  not  from  the  cen- 
tral grooved  part :  here  the  fibres  arise  from  tendinous  arches 


PSOAS   AND    ILIACUS.  399 

thrown  over  the  lumbar  vessels.  The  muscle  descends  vertically 
along  the  brim  of  the  pelvis,  beneath  the  crural  arch  into  the 
thigh,  and  is  inserted  by  a  strong  tendon  into  the  back  part  of  the 
lesser  trochanter  of  the  femur.  In  front,  the  psoas  has  in  relation 
with  it  the  ligamentum  arcuatum  internum,  the  external  iliac 
artery,  the  kidney  and  the  ureter,  the  spermatic  vessels,  the  genito- 
crural  nerve  and  the  vas  deferens ;  behind  it,  are  the  ilium,  the 
quadratus  lumborum,  the  lumbar  plexus  of  nerves,  and  the  obturator 
nerve  which,  lower  down,  runs  along  the  inner  border  of  the  muscle. 
Towards  its  insertion,  the  tendon  of  the  psoas  lies  between  the 
iliacus  and  the  pectineus. 

As  it  passes  under  the  crural  arch,  the  tendon  of  the  psoas  lies 
immediately  over  the  capsule  of  the  hip-joint,  and  there  is  a  large 
bursa  between  them  to  facilitate  the  play  of  the  tendon.  It  should 
be  borne  in  mind  that  occasionally,  even  in  young  subjects,  but 
more  frequently  in  old  ones,  in  consequence  of  wear  and  tear, 
this  bursa  communicates  with  the  hip-joint.  The  fact  is  im- 
portant ;  for  it  explains  how  a  psoas  abscess  sometimes  makes  its 
way  into  the  hip-joint :  a  result  frequently  fatal. 

PSOAS  PAKVUS  Once  in  about  eight  or  ten  subjects  there  is  a 

small  muscle  called  the  psoas  parvus.  It  arises 
from  the  bodies  of  the  last  dorsal  and  the  first  lumbar  vertebrae,  and 
the  intervening  fibro-cartilage ;  thence  descending  in  front  and  to 
the  inner  side  of  the  psoas  magnus,  it  ends  in  a  long  flat  tendon, 
which  spreads  out,  and  is  inserted  into  the  linea  ilio-pectinea. 

ILIACUS  INTBRNUS  This  muscle  occupies  the  iliac  fossa,  and  is 
AND  ILIAC  FASCIA,  covered  by  the  iliac  fascia.  This  iliac  fascia  is 
attached  to  the  crest  of  the  ilium,  and  indirectly  to  the  brim  of  the 
pelvis  through  its  connection  with  the  sheath  of  the  psoas.  Its 
most  important  attachment  is  to  the  outer  half  of  the  crural  arch  ; 
here  it  is  directly  continuous  with  the  fascia  transversalis  (p.  365), 
so  that,  together,  they  present  an  effectual  barrier  to  the  escape  of 
intestine  beneath  this  part  of  the  arch.*  The  external  iliac  artery 

*  The  iliac  fossae  are  liable  to  be  the  seat  of  suppuration,  and  the  course  which 
the  pus  takes  depends  upon  its  position  with  regard  to  the  iliac  fascia.  If  the 
pus  be  seated  in  the  loose  cellular  tissue  between  the  peritoneum  and  the  fascia,  it 


400  PSOAS   AND    ILIACUS. 

and  vein  lie  in  front  of  the  fascia,  while  the  anterior  crural  nerve 
is  behind  it. 

The  iliacus  internus  arises  from  the  iliac  fossa,  from  the  ilio- 
lumbar  ligament,*  and  from  the  capsule  of  the  hip-joint.  The 
fibres  converge  beneath  the  crural  arch,  and  are  inserted  mainly 
into  the  outer  side  of  the  tendon  of  the  psoas,  and  partly  into  the 
triangular  surface  of  the  femur,  below  and  anterior  to  the  lesser 
trochanter.  Thus  the  two  muscles,  so  far  as  their  action  goes, 
may  be  considered  as  one,  and  are  sometimes  called  the  ilio- 
psoas. 

The  combined  action  of  the  psoas  and  iliacus  is  to  assist  in 
raising  the  body  from  the  recumbent  position,  and  to  fix  the  pelvis 
steadily  on  the  thigh :  this  supposes  the  fixed  point  to  be  at  the 
trochanter  minor.  If  the  fixed  point  be  at  the  spine,  then  the 
muscle  flexes  and  rotates  the  femur  outwards.  It  is  this  action 
which  often  occasions  so  much  displacement  in  fractures  of  the 
upper  third  of  the  femur. 

Q0ADBATus  This  muscle  extends  from  the  crest  of  the  ilium 

LUMBORUM  AND  to  the  last  rib,  and  is  contained  in  a  sheath  formed 
ITS  SHEATH.  for  it  by  the  aponeurotic  origin  of  the  transver- 

salis  (p.  361).  The  anterior  layer  of  its  sheath  is  attached  to  the 
roots  of  the  transverse  processes  of  the  lumbar  vertebrae,  and  the 
posterior  layer  to  their  summits.  The  muscle,  broader  below  than 
above,  arises  from  the  ilio-lumbar  ligament  and  from  the  crest  of 
the  ilium  for  two  inches  external  to  it.  It  is  inserted  into  the 
last  rib,  and  by  tendinous  slips  into  the  transverse  processes  of 
the  upper  four  lumbar  vertebrae.  Besides  the  preceding,  a  few 
fibres  of  the  muscle  arise  from  the  transverse  processes  of  the 
third,  fourth  and  fifth  lumbar  vertebrae,  and,  running  up  in  front 
of  the  others,  are  inserted  in  common  with  them.  The  principal 
use  of  the  muscle  is  to  steady  the  spine ;  it  also  steadies  the  last 

usually  advances  just  above  the  crest  of  the  ilium,  or  towards  the  groin  through 
the  inguinal  canal ;  but,  if  seated  beneath  the  fascia,  the  matter  usually  makes  its 
way  under  the  crural  arch  towards  the  upper  and  outer  part  of  the  thigh. 

*  This  ligament  extends  from  the  transverse  process  of  the  last  lumbar  vertebra 
to  the  ilium. 


ABDOMINAL    AORTA.  401 

rib,  and  enables  it  to  serve  as  a  fixed  point  for  the  action  of  the 
intercostal  muscles  and  the  diaphragm.* 

By  raising  the  quadratus,  we  observe  the  aponeurotic  origin 
of  the  transversalis  from  the  summits  of  the  transverse  pro- 
cesses :  this  constitutes  the  posterior  part  of  its  sheath,  and 
separates  the  muscle  from  the  erector  spinae. 

Before  examining  the  course  of  the  aorta  and  its  great  primary 
divisions,  notice  that  a  chain  of  lymphatic  glands  extends  along 
the  brim  of  the  pelvis  and  the  bodies  of  the  lumbar  vertebrae, 
following  the  course  of  the  great  blood-vessels.  Generally 
speaking  they  are  small ;  only  one  here  and  there  attracts  obser- 
vation. They  transmit  the  lymphatics  from  the  lower  limbs,  the 
abdominal  wall,  and  the  testicle ;  and  all  eventually  lead  to  the 
receptacuLum  chyli,  or  beginning  of  the  thoracic  duct  (p.  142). 
This  is  usually  found  on  the  right  of  the  aorta,  close  to  the  second 
lumbar  vertebra. 

EELATIONS  OF  The   aorta   enters   the   abdomen    between   the 

THE  ABDOMINAL  crura  of  the  diaphragm  in  front  of  the  last  dorsal 
AosTA<  vertebra,  and  descends  a  little  to  the  left  side  of 

the  front  of  the  spine,  as  low  as  the  middle  of  the  fourth  lumbar 
vertebra,  where  it  divides  into  the  two  common  iliac  arteries.  The 
division  is  about  the  level  of  the  highest  point  of  the  crest  of 
the  ilium,  and  just  below  the  left  side  of  the  umbilicus.  The 
aorta  is  crossed  in  front  by  the  splenic  vein,  the  pancreas,  the  trans- 
verse portion  of  the  duodenum,  the  left  renal  vein,  the  mesentery  ; 
and  it  has  also  in  front  of  it  a  chain  of  lymphatic  glands.  To  the 
right  side  of  it  lie  the  vena  cava  inferior,  the  thoracic  duct,  the 
vena  azygos,  and  the  right  eras  of  the  diaphragm.  To  the  left 
side  of  it  is  the  left  crus,  and  on  each  side  are  the  sympathetic 
nerves. 

*  The  respective  attachments  of  the  quadratus  lumborum,  the  crossing  of  its 
fibres,  and  its  mode  of  action,  lead  to  the  inference  that  it  is  a  large  intercostal 
muscle.  It  is  worth  remembering  that  the  outer  edge  of  the  quadratus  lumborum,  in 
a  well-grown  adult,  is  about  three  inches  from  the  spines  of  the  lumbar  vertebrae, 
and  midway  between  the  last  rib  and  the  crest  of  the  ilium.  It  is  just  outside  the 
edge  of  this  muscle  that  we  can  cut  down  to  open  the  large  bowel  without  wounding 
the  peritoneum. 

D  D 


402  BRANCHES    OF    THE    ABDOMINAL    AORTA. 

The  branches  of  the  aorta  still  to  be  examined  arise  from  it 
in  pairs — namely,  the  phrenic,  capsular,  renal,  spermatic,  and 
lumbar.  (See  diagram  p.  384.) 

PHRENIC  These  arteries  supply  the  under  surface  of  the 

AKTERIES.  •  diaphragm,  and  arise  separately,  or  by  a  common 

trunk,  from  the  aorta  after  its  passage  under  the  pillars 
(p.  396).  The  right  phrenic  passes  outwards,  behind  the  vena 
cava,  the  left  behind  the  oasophagus ;  each  ascends,  lying  on  its 
corresponding  crus,as  far  as  the  central  tendon,  where  each  divides 
into  two  branches  :  one-which  passes  transversely  across  the  tendon 
to  the  side  ofr  the  diaphragm ;  the  other,  which  seems  to  be  the 
continuation  of  the  artery,  runs  forwards  to  the  anterior  part  of 
the  muscle.  Their  first  'branches  are  to  the  supra-renal  capsules  ; 
then  the  right  gives  off  a  small  branch  to  the  vena  cava,  the  left, 
one  to  the  ossophagus.  They  inosculate -with  each  other,  with  the 
internal  mammary,  and  the  intercostal  arteries.  The  right  phrenic 
vein  terminates  in  the  inferior  vena  cava ;  the  left,  in  the  renal 
vein,  if  not  in  the  vena  cava. 
SUPRA-RENAL  The  supra-renal  or  consular  arteries  are  two 

ARTERIES.  very  small   branches,  given  >off  from    the    aorta 

opposite  to  the  superior  mesenteric  artery;  -each  runs  upon  the 
crus  of  the  diaphragm,  the  right  behind  the  inferior  cava,  and  is 
distributed  to  the  supra-renal  body,  inosculating  with  branches 
from  the  phrenic  and  renal  arteries.  The  right  capsular  vein  ter- 
minates in  the  inferior  vena  cava,  the  left  in  the  left  renal. 

KENAL ARTE-  ''The  renal  arteries  arise  from  the  aorta  at  right 
HIES  AND  VEINS.  angles,  and  run  transversely  to  the  kidneys.  Both 
are  covered  by  their  corresponding  veins.  The  right  is  longer  and 
rather  lower  than  the  left,  •  and  passes  beneath  the  vena  cava. 
Each,  after  sending  a  small  branch  to  the  supra-renal  body,  enters 
its  kidney,  not  as  a  single  trunk,  but  by  several  branches,  corre- 
sponding to  the  original  lobes  of  the  organ.  The  renal  veins  lie 
in  front  of  the  arteries,  and  join  the  vena  cava  at  right  angles. 
The  left  is  longer  than  the  right,  and  crosses  over  the  aorta ;  it 
also  receives  the  spermatic,  capsular,  and  sometimes  the  phrenic 
veins  of  its  own  side. 


BRANCHES  OF  THE  ABDOMINAL  AORTA.         403 

SPERMATIC  The  spermatic  arteries,  two  in  number,  arise 

ARTERIES  AND  from  the  front  of  the  aorta,  a  little  below  the 
VEINS-  renal.  Each  runs  down  upon  the  psoas,  crossing 

over  the  ureter  and  over  the  front  of  the  external  iliac  artery  im- 
mediately above  the  crural  arch.  Each  then  passes  through  the 
internal  abdominal  ring  and  inguinal  canal,  with  the  other  con- 
stituents of  the  spermatic  cord  to  the  testicle.  Each  artery  is 
accompanied  by  two  very  tortuous  veins,  which  unite  before  they 
empty  themselves,  on  the  right  side  into  the  vena  cava,  on  the 
left,  into  the  renal  vein.  In  the  female,  the  ovarian  arteries  do 
not  leave  the  abdomen,  but  pass,  between  the  layers  of  the  broad 
ligaments,  to  the  ovaries. 

LUMBAR  There  are  five  of  these  arteries  on  either  side : 

ARTERIES  AND  four  arise  from  the  aorta,  the  fifth  comes  from  the 
BRANCHES.  arteria  sacra  media.  They  are  analogous  to  the 

intercostal  arteries  on  a  small  scale.  They  proceed  outwards  over 
the  bodies  of  the  vertebrae,  beneath  the  arch  formed  by  the  psoas 
muscle,  towards  the  intervertebral  foramina,  and  then,  like  the 
intercostals,  divide  into  dorsal  and  abdominal  branches.  The  two 
upper  lumbar  arteries  pass  beneath  the  crura  of  the  diaphragm, 
those  on  the  right  side  being  also  behind  the  vena  cava. 

The  dorsal  branches  pass  between  the  transverse  processes 
of  the  vertebrae,  accompanied  by  the  posterior  branches  of  the  cor- 
responding nerves,  and  are  of  a  size  proportionate  to  the  large 
development  of  the  muscles  of  the  back  which  they  supply.  They 
also  send  spinal  branches,  which  enter  the  spinal  canal  through 
the  intervertebral  foramina;  some  of  these  are  distributed  to  the 
anterior  part  of  the  cauda  equina,  and  others  to  the  bodies  of  the 
lumbar  vertebrae,  forming  a  series  of  arches  behind  them. 

The  abdominal  branches  all  run  outwards  behind  the  quadra- 
tus  lumborum,  except  the  last,  which  usually  runs  in  front.  After 
supplying  the  quadratus  and  psoas,  they  pass  forwards  between  the 
abdominal  muscles  and  supply  the  walls  of  the  abdomen.*  They 

*  Just  as  the  thoracic  intercostals,  by  communicating  with  the  internal  mammary, 
form  an  arterial  ring  round  the  chest,  so  do  the  lumbar,  by  communicating  with 
the  epigastric,  form  a  similar,  though  less  perfect,  ring  round  the  walls  of  the 
abdomen. 

D  n  2 


404  VENA   CAVA — COMMON    ILIAC    AETEEIES. 

anastomose,  laterally,  with  the  ilio-lumbar  and  circumflex  iliac 
arteries,  and,  in  front,  with  the  internal  mammary  and  epigastric 
arteries. 

The  lumbar  veins  empty  themselves  into  the  vena  cava  in- 
ferior. 

The  arteria  sacra  media,  a  diminutive  continuation  of  the 
aorta,  proceeds  from  its  bifurcation,  and  runs  down  in  front  of  the 
sacrum  to  the  coccyx.  It  sends  off  the  fifth  lumbar  artery,  and 
lateral  branches,  which  anastomose  with  the  lateral  sacral  arteries  ; 
it  also  supplies  small  vessels  to  the  posterior  part  of  the  rectum. 
Its  vein  empties  itself  either  into  the  left  common  iliac  vein,  or 
into  the  inferior  vena  cava.  In  animals  it  is  the  artery  of  the 
tail. 

VENA  CAVA  The  vena  cava  inferior  is  formed  by  the  junction 

INFERIOR.  of  the  two  common  iliac  veins,  a  little  to  the  right 

side  of  the  fifth  lumbar  vertebra.  It  ascends  on  the  right  of  the 
aorta,  close  to  the  spine  in  the  greater  part  of  its  course.  As  it 
approaches  the  diaphragm,  the  vena  cava  inclines  a  little  to  the 
right,  separated  from  the  aorta  by  the  right  crus,  to  go  through 
its  tendinous  opening  in  the  diaphragm,  and  reach  the  right  side 
of  the  heart.  Its  relations,  beginning  from  below,  are — in  front, 
the  mesentery,  the  third  part  of  the  duodenum,  the  pancreas,  the 
liver,  and  the  right  spermatic  artery ;  behind  it  are  the  right 
renal  artery,  the  right  lumbar  arteries,  and  the  sympathetic  of 
the  right  side.  It  receives  the  lumbar  veins,  the  right  spermatic 
(the  left  joins  the  renal),  the  renal,  the  capsular,  the  right  phrenic, 
and  the  hepatic  veins. 

COMMON  ILIAC  The  aorta  divides,  in  front  of  the  fourth  lumbar 

ARTERIES  AND  vertebra,  into  two  great  branches,  termed  the  com- 
VEINS-  mon  iliac  arteries.  They  diverge  at  an  acute  angle, 

and,  after  a  course  of  about  two  inches,  each  divides  over  the  sacro- 
iliac  symphysis,  into  the  external  and  internal  iliac.  They  lie 
upon  the  bodies  of  the  fourth  and  fifth  lumbar  vertebrae.  They 
are  covered  by  peritoneum,  and  crossed,  at  or  near  their  division,  by 
the  ureters.  They  are  also  crossed  by  branches  of  the  sympathetic 
on  their  way  to  the  hypogastric  plexus.  So  far,  then,  the  relations 


EXTERNAL    ILIAC    ARTERY.  405 

of  both  common  iliac  arteries  are  similar.    But  each  has  its  special 
relations  as  follows : — 

The  special  relations  of  the  right  common  iliac  are,  that  it  lies, 
at  its  commencement,  close  to  the  left  of  the  inferior  vena  cava ; 
and  that  it  subsequently  crosses  over  both  the  common  iliac  veins. 

The  special  relations  of  the  left  common  iliac  are,  that  it  has, 
in  front  of  it,  the  end  of  the  sigmoid  flexure  of  the  colon  and  the 
inferior  mesenteric  vessels  ;  and,  to  its  right  side,  the  common  iliac 
vein,  which  gradually  gets  more  behind  it  towards  the  sacro-iliae 
symphysis. 

The  relations  of  these  arteries  with  regard  to  their  corre- 
sponding veins  are,  practically,  important  in  reference  to  the  ope- 
ration of  tying  them.  This  operation  is.  obviously,  easier  on  the 
left  side  than  the  right.* 

If  the  common  iliac  artery  were  ligatured,  the  collateral  cir- 
culation would  be  maintained  through  the  following  vessels-:  by 
the  internal  mammary  anastomosing  with  the  deep  epigastric  a. ; 
by  the  lumbar  arteries  with  the  circumflex  iliac  and  the  ilio- 
lumbar  a. ;  by  the  lumbar  with  the  gluteal ;  by  the  middle  sacral 
with  the  lateral  sacral  a. ;  by  the  spermatic  with  the  deferential, 
cremasteric,  external  pudic  and  superficial  perineal  arteries ;  by 
the  superior  haemorrhoidai  with  the  middle  and  inferior  haemor- 
rhoidal  a. ;  by  the  lower  intercostals  with  the  epigastric  a.  (super- 
ficial and  deep)  ;  and  by  the  middle  and  the  inferior  haemorrhoidai, 
the  pudic  and  its  branches,  and  the  vesical  arteries  communica- 
ting in  the  middle  line  with  the  corresponding  branches  of  the 
opposite  side. 

EXTERNAL  The  external  iliac  artery  passes  along  the  brim 

ILIAC  AKTERT.         of  the  pelvis,  first  on  the  inner  side,  and  then  in 

*  The  length  of  the  common  iliac,  artery  is  apt  to  vary  in  different  persons.  We 
have  seen  it  from  three-fourths  of  an  inch  to  three  and  a  half  inches  long.  These 
varieties  may  arise  either  from  a  high  division  of  the  aorta,  or  a  low  division  of  the 
common  iliac,  or  both.  It  is  impossible  to  ascertain,  beforehand,  its  length  in  any 
given  instance,  as  there  is  no  necessary  relation  between  its  length  and  the  height  of 
the  adult  individual.  It  is  often  very  short  in  men  of  tall  stature,  and  vice  versa. 
The  left  is  usually  described  as  rather  longer  than  the  right ;  but,  from  the  examina- 
tion of  100  bodies,  our  conclusion  is  that  their  average  length  is  the  same. 


406  EXTERNAL    ILIAC    AETEET. 

front  of  the  psoas.  Lower  down  it  passes  under  the  crural  arch, 
midway  between  the  anterior  superior  spine  of  the  ilium  and  the 
symphysis  pubis,  and  takes  the  name  of  femoral.  The  artery  has 
in  front  of  it  the  peritoneum,  and  intestine ;  and,  just  above 
Poupart's  ligament,  the  deep  circumflexa  ilii  vein,  the  spermatic 
vessels,  and  the  vas  deferens.  On  its  inner  side,  and  on  a  plane 
somewhat  posterior,  is  the  corresponding  vein.  The  iliac  fascia 
lies  behind  the  vessels,  but  a  thin  layer  of  fascia  derived  from  it 
is  continued  over  them.  In  front  of  the  artery  are  a  chain  of 
lymphatic  glands. 

The  branches  given  off  by  this  artery  are  : — 
The  deep  epigastric,  already  described  (p.  366). 
The  deep  circumflexa  ilii,  which  arises  from  the  outer  side  of 
the  artery,  just  above  the  crural  arch,  and  running  towards  the 
anterior  superior  spine  of  the  ilium  in  a  sheath  formed  by  the 
fascia  iliaca,  subsequently  perforates  the  transversalis  muscle.*  In 
the  dissection  of  the  abdominal  muscles  (p.  367),  the  continuation 
of  it  was  seen  skirting  the  crest  of  the  ilium  between  the  internal 
oblique  and  the  transversalis,  and  sending  a  branch  upwards  be- 
tween these  muscles  for  their  supply.  The  main  trunk,  much 
reduced  in  size,  inosculates  with  the  ilio-lumbar  derived  from  the 
internal  iliac. 

LIGATUKE  OF  ^^&  best  way  of  tying  the  external  iliac  is  to 

THE  EXTERNAL  make  a  curved  incision  at  the  lower  part  of  the 
ILIAC-  abdomen,  beginning  a  little  above  the  middle  of 

the  crural  arch,  and  ending  about  an  inch  to  the  inner  side  of  the 
spine  of  the  ilium.  The  strata  of  the  abdominal  muscles,  with 
the  fascia  transversalis,  should  then  be  divided  to  the  same  extent ; 
after  which,  the  peritoneum  with  the  spermatic  vessels  must  be 
separated  by  the  fingers  from  the  iliac  fossa.  It  is  necessary  to 
make  a  small  incision  through  the  sheath  of  the  vessel,  to  facilitate 
the  passage  of  the  needle.  Remember  that  the  vein  is  closely 
connected  to  its  inner  side,f  that  the  genito-crural  nerve  is  not 

*  The  course  of  this  artery  should  be  borne  in  mind  in  opening  iliac  abscesses, 
f  This  relative  position  of  the  vessels  does  not  always  exist.     In  old  subjects, 
less  frequently  in  adults,  it  is  sometimes  found  that  the  external  iliac  artery  runs  very 


SYMPATHETIC    IN    THE    ABDOMEN. 

far  off,  and  that -the  circumflex  iliac  vein  crosses  the  artery  just 
above  Poupart's  ligament. 

After  ligature  of  the  artery  the  collateral  circulation  would  be 
maintained  by  anastomoses  between  the  internal  mammary  and  the 
deep-epigastric;  between  the  lumbar  arteries  and,  the  circumflex 
iliac;  between  the  pubic  branch  of  the  obturator*  and  the  branch 
of  the  epigastric;  between  the  gluteal.and  the,  internal  .and 
external  circumflex;  between  the.  sciatic  and  the  first  perforating 
and  the  internal  circumflex;  between  the  obturator,  and  the  in- 
ternal circumflex;  between  the  spermatic,  the  deferential,  and  the 
cremasteric  and  the  external  pudic;  between  the  lower  intercostals 
and  the  lumbar  arteries  and  the  epigastric  artery. 

SYMPATHETIC  The  general  plan  upon  which  the  sympathetic 

NERVE.  nerve  is  arranged    has  been  noticed  in  the  dis- 

section of -the  neck' (p. ..1 14).  The  lumbar  portion  of  it  must  now 
be  examined-. 

The  abdominal  part  of  the  sympathetic  descends  on  either  side 
in  front  of  the  bodies  of  the  lumbar  vertebrae,  along  the  inner 
border  of  the  psoas.  The  nerve  has  an  oval  ganglion  opposite  each 
lumbar  vertebra,  so  that  there  are  five  on  each  side.  These  ganglia 
are  connected  by  small  filaments,  and  each  ganglion  receives  two 
branches  from  the  corresponding  spinal  nerve,  as  in  the  chest. 

SOLAR  PLEXUS  The  solar  plexus  is  situated  in  front  of  the 
AND  THE  SEMI-  aorta  and  surrounds  the  coeliac  axis  in  a  dense 
LUNAR  GANGLIA.  network  of  nerve-filaments,  on  •  which  are  several 

tortuously,  instead  of  nearly  straight,  along  the  brim  of  the  pelvis.  But  the  vein  dees 
not  follow  the  artery  in  its  windings,  and  may  possibly  lie  outside  the  artery  just 
where  we  propose  to  place  the  ligature. 

The  mode  of  performing  the  operation  described  in  the  text  is  recommended  by 
Sir  A.  Cooper.  Mr.  Abernethy,  however,  who  first  set  the  example  of  tying  this 
artery,  in  1796,  adopted  a  somewhat  different  proceeding.  He  says:  'I  first  made 
an  incision  about  three  inches  in  length  through  the  integuments  of  the  abdomen,  in 
the  direction  of  the  artery,  and  thus  laid  bare  the  aponeurosis  of  the  external  oblique 
muscle,  which  I  next  divided  from  its  connection  with  Poupart's  ligament,  in  tha 
direction  of  the  external  wound,  for  the  extent  of  about  two  inches.  The  margins  of 
the  internal  oblique  and  transversalis  muscles  being  thus  exposed,  I  introduced  my 
finger  beneath  them  for  the  protection  of  the  peritoneum,  and  then  divided  them . 
Next,  with  my  hand,  I  pushed  the  peritoneum  and  its  contents  upwards  and  inwards, 
and  took  hold  of  the  artery.' 


408  LUMBAR    PLEXUS. 

ganglia.  It  receives  the  splanchnic  nerves,  and  some  branches 
from  the  pneumogastric  nerves ;  and  it  gives  off  filaments  which 
surround  the  various  branches  of  the  abdominal  aorta,  the  plexuses 
thus  formed  taking  the  name  of  the  arteries  they  accompany. 

The  semilunar  ganglia  are  situated,  one  on  each  side  of  the 
coeliac  axis,  and  internal  to  the  supra-renal  capsules.  These  ganglia 
have  been  described  (p.  395). 

The  plexuses  connected  with  these  nervous  centres  are, — the  dia- 
phragmatic, the  superior  mesenteric,  the  supra-renal,  the  renal,  the 
spermatic,  the  coronary  hepatic  and  splenic,  the  aortic,  and  the  inferior 
mesenteric. 

HYPOGASTRIC  The  hypogastric  plexus  is  situated  between  the 

PLEXUS.  common  iliac  arteries,  on  the  last  lumbar  vertebrae 

and  the  sacrum.  It  consists  of  an  intricate  interlacement  of 
sympathetic  filaments,  which  pass  down  into  the  pelvis,  for  the 
supply  of  the  pelvic  viscera.  Although  this  plexus  is  so  in- 
tricate, it  presents  no  distinct  ganglia.  As  it  passes  down  it 
receives  branches  from  some  of  the  spinal  nerves,  but  mainly 
from  the  third  and  fourth  sacral  nerves.  From  this  large  plexus 
are  derived  secondary  plexuses,  which  ramify  around  branches  of 
the  internal  iliac  artery :  thus  there  are,  the  inferior  hsemorrhoidal 
plexus,  the  vesical,  the  uterine,  the  ovarian,  the  prostatic,  and 
the  vaginal ;  all  of  which  send  filaments  which  accompany  the 
smallest  branches  of  the  arteries. 

LUMBAR  The    lumbar   plexus   is   formed   by   the  union 

PLEXUS  OF  of  the  anterior  branches  of  the  four  upper  lum- 

NERVES.  ^  nerves>      ^he  fifth  does   not  enter   into   the 

formation  of  this  plexus,  but  joins  the  sacral  plexus  under  the 
name  of  the  lumbo-sacral  cord.  The  plexus  lies  over  the  transverse 
processes  of  the  corresponding  vertebras,  embedded  in  the  substance 
of  the  psoas,  so  that  this  muscle  must  be  dissected  away  before  the 
plexus  can  be  seen.  Like :  the  brachial  plexus,  the  nerves  com- 
posing it  successively  increase*  in  .size. from  above.  Its  branches 
are  five  in  number,  and  arise  imthe  following  order  (fig.  86). 

a.  The  first  lumbar '\nerve  generally  divides  into  two  branches  ; 


LUMBAR    PLEXUS. 


409 


the  upper  being  the  ilio-hypogastric,  the  lower  the  ilio  inguinal. 
They  cross  obliquely  over  the  quadratus  lumborum  to  the  crest  of 
the  ilium,  and  then  separate.  The  ilio-hypogastric  passes  forwards 
to  the  crest  of  the  ilium,  where  it  pierces  the  transversalis,  and 
divides  into  its  two  terminal  branches — the  iliac  branch,  which 
supplies  the  skin  over  the  glutseal  region,  behind  the  last  dorsal 
nerve,  and  the  hypogastric  branch,  which  runs  forward  between  the 
transversalis  and  internal  oblique,  and  then  perforates  the  aponeu- 


-  a.  Hio-bypogastric  n. 
6.  Hio-inguinal  n. 
c.^External  cutaneousn. 

d.  Anterior  crural  n. 

e.  Crural  branch  of  genito- 

crural  n. 
/.  Obturator  n. 
y.  Genital  branch  of  genito- 

cruraln. 
h.  Lumbo-sacral  n. 


1 .  First  lumbar  n. 

2.  Second    „    „ 

3.  Third      „    „ 

4.  Fourth    ,, 
-5.  Fifth       „ 


PLAN   OF    THE    LUMBAR    PLEXUS    AND    BRANCHES. 

rosis  of  the  external  oblique  to  supply  the  skin.  The  ilio-inguinal, 
the  smaller,  perforates  the  transversalis  and  internal  oblique,  comes 
out  through  the  external  abdominal  ring  in  front  of  the  spermatic 
cord,  and  supplies  the  skin  of  the  penis  and  scrotum  in  the  male, 
and  the  labium  in  the  female. 

6.  The  genito-crural  nerve  is  small,  and  comes  from  the 
second  lumbar.  After  perforating  the  psoas,  it  runs  down  along 
the  outer  side  of  the  external  iliac  artery,  .and  near  the  crural 


410  LUMBAR    PLEXUS. 

arch  divides  into  the  genital  branch  ((7),  which  runs  along  the 
inguinal  canal,  on  the  under  aspect  of  the  spermatic  cord,  and 
supplies  the  cremaster  ;  and  the  crural  (e\  which  proceeds  under 
the  crural  arch,  and  is  lost  in  the  skin  of  the  upper  part  of  the 
thigh,  where  it  communicates  with  the  middle  cutaneous  -nerve. 

c.  The  external  cutaneous  nerve  of  the   thigh   is   generally 
derived   from   the  second  lumbar.       It  runs  through  the   psoas, 
then,  crossing  obliquely  over  the  iliacus  towards  the  spine  of  the 
ilium,  passes  beneath  the  crural  arch,  and  is  finally  distributed  to 
the  skin  on  the  outside  of  the  thigh.     If  the  external  cutaneous  be 
not  found  in  its  usual  situation,  look  for  it  as  a  distinct  branch  of 
th  e  anterior  crural,  nearer  the  psoas  muscle. 

d.  The  anterior  crural  (d),  the  largest  and  most  important 
branch,  is  formed  by  the  union  x>f  the  third  and  fourth  lumbar 
nerves,  sometimes  receiving  a  small  'branch  from  the   second.     It 
descends  in  a  groove  between  the  psoas  and  the  iliacus  behind  the 
fascia  iliaca,  supplies  both  these  muscles,  and  then,  passing  under 
the  crural  arch  to  the  outer  side  of  the  femoral  artery,  is  finally 
distributed  to  the  extensor  muscles  of  the  knee,  to  the  sartorius 
and  pectineus,  and  the  skin  of  the  thigh  and  leg. 

e.  The  obturator  nerve  (/)  is  next  in  size  to  the  anterior  crural. 
It   proceeds  from  the  third  and  fourth  lumbar  nerves,  descends 
behind  the  psoas  muscle,  and  then,  getting  to  its  inner  border  it 
runs  along  the  brim  of  tfofe  pelvis  to  the  obturator  foramen,  through 
the  upper  part  of  which  it  passes  to  the  adductor  muscles  of  the 
thigh. 

/.  The  accessory  obturator  nerve,  by  no  means  a  constant 
branch,  is  derived  from  the  third  and  fourth  lumbar  nerves.  It 
descends  over  the  horizontal  ramus  of  the  pubes,  supplies  the  pec- 
tineus and  gives  off  a  small  branch  to  the  hip  joint. 

Postponing  the  minute  anatomy  of  the  abdominal  viscera, 
begin  the  examination  of  the  contents  of  the  pelvis. 


THE    PELVIS    AND    ITS    FUNCTIONS.  411 


DISSECTION    OF   THE  PELVIC   VISCERA. 

The  functions  of  the  pelvis  are  to  protect  its  own  viscera ;  to 
support  those  of  the  abdomen  ;  to  give  attachment  to  the  muscles 
which  steady  the  trunk  ;  to  transmit  the  weight  of  the  trunk  to 
the  lower  limbs,  and  to  give  origin'  to  the  muscles  which  move 
them.  In  adaptation  to  these  functions,  the  form  of  the  pelvis 
is  that  of  an  arch,  with  broadly  expanded  wings  at  the  sides, 
and  projections  in  appropriate  situations  to  increase  the  leverage 
of  the  muscles-  The  sacrum,  impacted  between  the  ilia,  repre- 
sents the  key-stone-  of  the  arch,  and  is  capable  of  supporting  not 
only  the  trunk,  but  great  burdens  besides.  The  sides  or  pillars 
are  represented  by  the  ilia ;  these  transmit  the  weight  to  the 
heads  of  the  tbigh*bones,  and  are  thickest  and  strongest  just  in 
that  line,  i.e.  the  brim  of  the  pelvis,  along  which  the  weight  is 
transmitted.  Moreover,  to  effect  the  direct  transmission  of  the 
weight,  the  plane  of  the  arch  is  oblique.  This  obliquity  of  the 
pelvis,  its  hollow  expanded  sides,,  its  great  width,,  the  position  and 
strength  of  the  tuberosities  of  the  ischia,  are  so  many  proofs  that 
man  is  adapted  to  the  erect- posture. 

The  general  conformation  of  the  pelvis  in  the  female  is 
modified,  so  as  to  be  adapted  to  utero-gestation  and  parturition. 
Its  breadth  and  capacity  are  greater  than  in  the  male.  Its  depth 
is  less.  The  alee  of  the  iliac  bones  are  more  expanded.  The 
projection  of  the  sacrum  is  less  perceptible^  and  consequently 
the  brim  is  more  circular.  The  span  of  the  pubic-  arch  is  wider. 
The  bones,  too,  are  thinner,  and  the-  muscular  impressions  less 
strongly  marked. 

The  cavity  of  the  pelvis  being  curved,  the  axis,  or  a  central 
line  drawn  through  it,  must  be  curved  in  proportion.  For  all 
practical  purposes,  it  is  sufficient  to  remember  that  the  axis  of 
the  pelvis  corresponds  with  a  line  drawn  from  the  anus  to  the 
umbilicus.* 

*  In  a  well-formed  female  the  base  of  the  sacrum  is  about  four  inches  higher  than 
the  upper  part  of  the  symphysis  pubis,  and  the  point  of  the  coccyx  is  rather  more 
than  half  an  inch  higher  than  the  lower  part  of  the  symphysis. 

The  obliquity  of  the  pelvis  is  greatest  in  early  life.     In  .the  foetus,  and  in  young 


412  RECTO- VESICAL    POUCH. 

CONTENTS  OF  The  male  pelvis  contains  the  last  part  of  the 

THE  MALE  PELTIS.  intestinal  canal,  named  the  rectum,  the  bladder 
with  the  prostate  gland  at  the  neck,  and  the  vesiculse  seminales. 
If  the  bladder  be  empty,  some  of  the  small  intestine  will  be  in 
the  pelvis  ;  not  so  if  the  bladder  be  distended. 

COURSE  OF  The  rectum  enters  the  pelvis  on  the  left  side 

THE  EECTUM.  of  the  sacrum,  and,  after  describing  a  curve  cor- 

responding with  the  concavity  of  the  sacrum,  terminates  at  the 
anus.  In  the  first  part  of  its  course,  it  is  loosely  connected  to 
the  back  of  the  pelvis  by  a  peritoneal  fold,  called  the  meso- 
rectum :  between  the  layers  of  this  fold,  the  superior  hsemor- 
rhoidal  vessels,  the  continuation  of  the  inferior  mesenteric,  with 
nerves  and  lymphatics,  runs  to  the  bowel. 

The  rectum  does  not  take  this  course  in  all  cases ;  sometimes 
it  makes  one,  or  even  two  lateral  curves.  In  some  rare  cases  it 
enters  the  pelvis  on  the  right  side  instead  of  the  left.  Since 
these  variations  from  the  usual  arrangement  cannot  be  ascertained 
during  life,  they  should  make  us  cautious  in  the  introduction  of 
bougies.* 

KECTO-VESICAL          Whilst  the  parts  are    still  undisturbed,  intro- 
POUCH.  duce     the    finger   into  -the    recto^vesicdl    peri- 

toneal pouch  (fig.  8£).  This  is  a  cul-de-sac  formed  by  the 
peritoneum  in  passing  from  the  front  of  the  rectum  to  the 
lower  and  back  part  of  the  bladder.  In  the  adult  male, 
the  bottom  of  this  pouch  is  about  one  inch  distant  from  the  base 
of  the  prostate  .gland :-f-  therefore  part  of  "the  under  surface 
of  the  bladder  is  not  covered  by  peritoneum ;  and  since  this 
part  is  in  immediate  contact  with  the  rectum,  it  is  practicable 
to  tap  the  distended  bladder  through  the  front  of  the  bowel 
without  injuring  the  peritoneum.  The  operation  has,  of  late 

children,  its  capacity  is  small ;  and  the  viscera,  which  subsequently  belong  to  it,  are 
situated  in  the  abdomen. 

*  In  old  age  the  rectum  has  sometimes  a  zigzag  appearance  immediately  above 
the  anus.  These  lateral  inclinations  are  probably  produced  by  the  enormous  disten- 
sions to  which  the  bowel  has  been  occasionally  subjected. 

f  The  bottom  of  the  pouch  is  from  three  to  four  inches  distant  from  the  anus. 


KECTO-VESICAL    POUCH. 


413 


years,  been  revived,  and  with  great  success.*  It  is  easily  done, 
and  not  attended  with  risk,  provided  all  the  parts  be  in  their 
regular  position.  But  this  is  not  always  the  case.  It  sometimes 
happens  that  the  peritoneal  pouch  comes  down  nearer  to  the 
prostate  than  usual — we  have  seen  it  in  actual  contact  with  the 
gland ;  so  that,  in  such  a  case,  it  would  be  impossible  to  tap 
the  bladder  from  the  rectum  without  going  through  the  peri- 
toneum. In  children  the  peritoneum  comes  down  lower  than  it 
does  in  the  adult,  because  the  bladder  in  the  child  is  not  a  pelvic 
viscus. 

FIG.  87. 


Symphysis  pubis 


Corpus  cavernosnm 
penis 


Peritoneum  in  dot- 
ted outline. 


Ureter. 

Vas  deferens. 
Vesicula  seminalis. 


Glans  penis     .    .    . 

Corpus  spongiosum 
urethras  .    .    .    . 


Bulb  of  corp.  spon- 
giosum .  .  .  . 

Cowper's  gland  with 
duct 

Membranous  part 
of  urethra  sur- 
rounded by  com- 
pressor muscle. 

Prostate  gland 


DIAGEAM    OF   THE    RELATIVE    POSITION    OF   THE   PELVIC    VISCERA. 

The  recto- vesical  pouch  is  permanent.  But  there  is  another 
peritoneal  pouch  on  the  front  part  of  the  bladder,  which  is  only 
produced  when  the  bladder  is  distended.  To  produce  it,  the 
bladder  should  be  blown  up  through  one  of  the  ureters.  The 
bladder  soon  fills  the  pelvis,  and  then,  rising  into  the  abdomen, 
occasions  the  pouch  between  it  and  the  abdominal  wall.  At 
first,  the  pouch  is  shallow,  but  it  gradually  deepens  as  the  bladder 


*  See  a  paper  in  the  '  Med.  Chir.  Trans.'  voL  xxxv-by  Mr.  Cock. 


414  DISSECTION    OP   THE    MALE    PERINEUM. 

rises.  If  the  bladder  be  distended  half-way  up  to  the  umbilicus, 
which  is  commonly  the  case  when  it  'has  to  be  tapped,  we  find 
that  the  bottom  of  the  pouch  would  be  about  two  inches  from 
the  symphysis  pubis  (fig.  87).  Within  this  distance  from  the 
symphysis,  the  bladder  may  be  tapped  in  the  linea  alba,  with- 
out risk  of  wounding  the  peritoneum.  Thus,  the  surgeon  "has 
the  choice  of  two  situations  in  which  he  may  tap  the  bladder 
— above  the  pubes,  or  from  the  rectum.  Which  of  the  two  be 
the  more  appropriate,  must  be  decided  by  the  circumstances  of 
the  case. 

DISSECTION   OF  THE  MALE  PERINEUM. 

Before  dissecting  the  perineum,  it  is  expedient  first  to  ex- 
amine the  osseous  and  ligamentous  boundaries  of  the  lower  aper- 
ture of  1She  pelvis.  Looking  at  the  male 
pelvis  (with  the  ligaments  -preserved), 
we  observe  that  this  aperture  is  of  a 
lozenge  shape ;  that  it  is  bounded  in 
front  by  the  symphysis  of  the  pubes, 
laterally  by  the  rami  of  the  pubes  and 
ischium  ;  behind,  by  the  coccyx  and  the 
great  saero-ischiatic  ligaments. 

This    space,  for  convenience  of   de- 
scription, is  divided  into  two  by  a  line 
DIAGRAM  OF  THE  FRAMEWORK  drawn  from  one  tuber  ischii  to  the  other. 
OF  THE  PERINEUM.  Tfae  anterior  forms  a  Dearly  equilateral 

triangle,  of  wMch  the  sides  are  from  three  to  three  and  a-half 
inches  long  4  and  since  it  transmits  the  urethra,  it  is  called  the 
urethral  division  of  the  perineum.  The  posterior,  containing  the 
anus,  is  called  the  anal  division  (fig.  88,  2).* 

The  subject  should  be  placed  in  the  usual  position  for  lithotomy, 
with  a  full-sized  staff  in  the  bladder,  the  rectum  moderately  dis- 
tended with  tow,  and  the  scrotum  raised  by  means  of  hooks.  A 

*  The  dimensions  of  the  lower  outlet  of  the  pelvis  are  apt  to  vary  in  different 
subjects,  and  the  lithotomist  must  modify 'his  incisions  accordingly. 


DISSECTION    OF    THE    MALE    PEKINEUM.  415 

central  ridge,  named  the  rapJie,  extends  from  the  anus,  along  the 
perineum,  scrotum,  and  under  surface  of  the  penis.  Between  the 
tuberosities  of  the  ischia  and  the  anus  are  two  depressions,  one  on 
each  side,  marking  the  ischio-rectal  fossce,  which  are  found  imme- 
diately beneath  the  skin,  filled  with  more  or  less  fat.  In  the  lateral 
operation  of  lithotomy,  the  incision  should  commence  at  a  point 
midway  between  the  anus  and  the  posterior  fold  of  the  scrotum, 
close  to  the  left  side  of  the  raphe ;  it  should  be  carried  downwards 
and  outwards  to  a  point  midway  between  the  tuber  ischii  and  the 
anus.  In  the  bilateral  operation,  the  incision  is  semi-lunar,  the, 
horns  being  made  on  either  side  between  the  tuber  ischii  and  the 
anus,  equidistant  from  these  points  respectively ;  while  the  centre  of 
the  incision  runs  about  three-quarters  of  an  inch  above  the  anus. 

At  the  anus  the  skin  becomes  finer  and  more 
delicate,  forming  a  gradual  transition  towards 
mucous  membrane :  during  life  it  is  drawn  into  wrinkles  by  the 
permanent  contraction  of  the  cutaneous  sphincter.  Moreover,  the 
skin  at  the  margin  of  the  anus  is  provided  with  numerous  minute 
glands,*  which  secrete  an  unctuous  substance  to  facilitate  the 
passage  of  the  faeces.  When  this  secretion  becomes  defective  or 
vitiated,  the  anal  cutaneous  folds  are  apt  to  become  excoriated, 
chapped,  or  fissured ;  and  then  defsecation  becomes  very  painful. 

The  skin   should   be  reflected,  by  making1  an 

DISSECTION 

incision  along  the  raphe,  round  the  margin  of  the 
anus  to  the  coccyx.  Two  others  must  be  made  on  each  side  at 
right  angles  to  the  first,  the  one  at  the  upper,  and  the  other  at  the 
lower  end  of  it.  The  skin  of  the  perineum  .must  then  be  reflected 
SUBCUTANEOUS  outwards.  In  reflecting  the  skin,  notice  the  .charac- 
TISSUE.  ters  of  the  subcutaneous  structure.!  Its  characters 

*  These  glands  are  the  analogues  of  the  anal  glands  in  some  animals,  e.g.  the  dog 
and  the  beaver.  They  are  found  not  only  about  the  anus,  but  also  in  the  subcutaneous 
tissue  of  the  perineum,  a  fact  for  the  demonstration  of  which  we  are  indebted  to 
the  late  Professor  Quekett.  They  are  large  enough  to  be  seen  with  the  naked  eye. 

t  The  probable  thickness  of  this  subcutaneous  tissue  is  a  point  whieh  ought  to  be 
determined  by  the  lithotomist  in  making  his  first  incision.  Its  great  thickness  in  some 
cases  explains  the  depth  to  which  the  surgeon  has  to  cut  in  letting  out  pus  from  the 
ischio-rectal  fossa. 


416  DISSECTION   OP   THE    MALE    PERINEUM. 

alter  in  adaptation  to  the  exigencies  of  each  part.  On  the  scro- 
tum the  fat  constituent  of  the  tissue  is  entirely  absent ;  while 
the  connective  tissue  element  is  most  abundant,  and  during  life 
elastic  and  contractile.  But,  towards  the  deeper  part  of  the  anus, 

FAT  IN  ISCHIO-  the  fat  accumulates  more  and  more,  and  on  either 
RECTAL  FOSSJK.  s{^e  of  the  rectum  it  is  found  in  the  shape  of  large 
masses,  filling  up  what  would  otherwise  be  two  deep  hollows  in  this 
situation — namely,  the  ischio-rectal  fossce.  These  fossse  are  tri- 
angular, with  their  bases  towards  the  skin,  and  their  apices  at  the 
divergence  of  the  obturator  internus  and  levator  ani.  They  are 
about  two  inches  in  depth,  and  much  deeper  posteriorly  than 
in  front.  This  accumulation  of  fat  on  each  side  of  the  anus, 
permits  the  easy  distension  and  contraction  of  the  lower  end  of 
the  bowel  during  and  after  the  passage  of  the  faeces.  Over  the 
tuberosities  of  the  ischia  are  large  masses  of  fat,  separated  by 
tough,  fibrous  septa,  passing  from  the  skin  to  the  bone,  so  as  to 
make  an  elastic  padding  to  sit  upon.  Occasionally,  too,  there  are 
one  or  more  large  bursce,  interposed  between  this  padding  and  the 
bone. 

So  much  respecting  the  general  characters  of  the  subcutaneous 
tissue  of  the  perineum.  Some  anatomists  describe  it  as  consisting 
of  three,  four,  or  even  more  layers,  but  in  nature  we  do  not  find  it 
so.  It  may,  indeed,  be  divided  into  as  many  layers  as  we  please, 
according  to  our  skill  in  dissection ;  but  this  only  complicates 
what  is,  in  itself,  simple. 

The  external  sphincter  ani  must  now  be  cleaned ; 
care  being  taken  not  to  remove  any  of  its  fibres  ; 
which  are  intimately  connected  with  the  skin.  Posteriorly,  the 
lower  border  of  the  glutens  maximus  must  be  displayed,  and  the 
vessels  and  nerves  crossing  the  perineum,  towards  the  anus,  care- 
fully dissected. 

EXTERNAL  The  external  sphincter  of  the  anus  is  elliptical, 

SPHINCTER  ANI.  an(j  arises  from  the  point  of  the  coccyx,  and 
the  ano-coccygeal  ligament.  The  muscular  fibres  surround  the 
anus,  and  are  inserted  in  a  pointed  manner  in  the  tendinous  centre 
of  the  perineum  (p.  419).  It  is  called  the  external  sphincter,  to 


DISSECTION    OP    THE    MALE    PEEINEUM.  41 7 

distinguish  it  from  a  deeper  and  more  powerful  band  of  muscular 
fibres  which  s,urrounds  the  last  inch  or  more  of  the  rectum,  and  is 
situated  next  to  the  mucous  membrane. 

CUTANEOUS  ^he  cutaneous  vessels  and  nerves  of  the  peri- 

VESSELS  AND  neum  come  from  the  internal  pudic  artery  and 

NEBVES.  nerve,  and  chiefly  from  that  branch  of  it  called  the 

superficialis  perinei.     This  will  be  traced  presently. 

The  external  or  inferior  hcemorrhoidal  arteries,  cross  trans- 
versely through  the  ischio-rectal  fossa,  from  the  ramus  of  the 
ischium  towards  the  anus.  They  come  from  the  pudic  (which  may 
be  felt  on  the  inner  side  of  the  ischium),  and  running  inwards, 
divide  into  numerous  branches,  which  supply  the  rectum,  levator 
ani,  and  sphincter  ani.  The  nerve  which  accompanies  the  artery 
comes  from  the  pudic,  and  supplies  the  sphincter  ani  and  the  skin 
of  the  perineum. 

The  fourth  sacral  nerve  emerges  through  the  coccygeus  close 
to  the  tip  of  the  coccyx,  and  supplies  the  skin  of  the  perineum 
between  this  bone  and  the  anus. 

The  inferior  pudendal  nerve  comes  through  the  muscular 
fascia  of  the  thigh,  a  little  above  the  tuber  ischii,  and  ascends, 
dividing  into  filaments,  which  supply  the  front  and  outer  part  of 
the  scrotum  and  perineum.  It  is  a  branch  of  the  lesser  ischiatic 
nerve,  and  communicates  in  front  with  the  posterior  branch  of  the 
superficial  perineal  nerve. 

SUPERFICIAL  The   subcutaneous    fascia  of  the  perineum   is 

FASCIA  OF  THE  composed  of  a  superficial  and  a  deep  layer.  The 
PERINETJM.  superficial  layer  contains  more  or  less  fat,  and  is 

continuous  with  that  of  the  scrotum,  the  thighs,  and  the  posterior 
part  of  the  perineum.  The  deeper  layer  is  best  demonstrated  by 
blowing  air  beneath  it  with  a  blow-pipe ;  its  connections  are  as 
follows : — It  is  attached  on  each  side  to  the  anterior  lip  of  the 
ramus  of  the  pubes  and  ischium ;  traced  forwards,  it  is  directly 
continuous  with  the  tunica  dartos  of  the  scrotum ;  traced  back- 
wards, at  the  base  of  the  urethral  triangle,  it  is  reflected  beneath 
the  transversus  perinei  muscle,  and  joins  the  deep  perineal  fascia 
or  triangular  ligament.  These  connections  explain  why  urine, 

E  E 


418  DISSECTION    OF    THE    MALE    PERINEUM. 

effused  into  the  perineum,  does  not  make  its  way  into  the  ischio- 
rectal  fossae,  or  down  the  thighs,  but  passes  readily  into  the  scrotum 
and  penis. 

Remove  the  fascia   to   see   the  muscles  which 

DISSECTION* 

cover  the  bulb  of  the  urethra  and  the  crura  of  the 

penis.  The  bulb  of  the  urethra  lies  in  the  middle  of  the  peri- 
neum, and  is  covered  by  a  strong  muscle,  called  accelerator  urinae. 
The  crura  penis  are  attached,  one  to  each  side  of  the  pubic  arch, 
and  are  covered  each  by  a  muscle,  called  erector  penis.  A  narrow 
slip  of  muscle,  called  transversus  perinei,  extends  on  either  side 
from  the  tuber  ischii  to  the  central  tendinous  point  of  the  peri- 
neum. This  point  is  about  one  inch  and  a  quarter  in  front  of  the 
anus,  and  serves  for  the  attachment  of  muscular  fibres  from  all 
quarters  of  the  perineum. 

Thus  the  muscles  of  the  perineum  describe  on  each  side  a 
triangle,  of  which  the  sides  are  formed  by  the  accelerator  urinse 
and  the  crus  penis  respectively,  and  the  base  by  the  transversus 
perinei.  Across  this  triangle  run  up  from  base  to  apex  the  super- 
ficial perineal  vessels  and  nerves.  External  to  the  ramus  of  the 
ischium  is  seen  the  inferior  pudendal  nerve,  a  branch  of  the 
lesser  ischiatic. 

SUPERFICIAL  The    superficial  perineal  artery    comes    from 

PERINEAL  VESSELS  the  internal  pudic  as  it  runs  up  the  inner  side  of 
AND  NERVES.  foe  tuber  ischii.  Though  the  main  trunk  cannot 

be  seen,  it  can  be  easily  felt  by  pressing  the  finger  against  the 
bone.  The  artery  comes  into  view  a  little  above  the  level  of  the  - 
anus,  passes  up  the  perineal  triangle,  distributing  branches  to  all 
the  muscles,  and  is  finally  lost  on  the  scrotum.  The  only 
named  branch  is  called  transversalis  perinei  (fig.  89).  This 
is  given  off  near  the  base  of  the  triangle,  and  runs  with  the 
transversus  perinei  muscle  towards  the  central  point  of  the 
perineum,  where  it  anastomoses  with  its  fellow.  It  is  necessarily 
divided  in  the  first  incision  in  lithotomy,  and  deserves  attention, 
because  it  is  sometimes  of  considerable  size. 

The  artery  is  accompanied  by  two  veins,  which  are  frequently 
dilated  and  tortuous,  especially  in  diseased  conditions  of  the  scrotum. 


DISSECTION    OF    THE    MALE    PERINEUM. 


419 


The  nerves,  two  in  number,  are  derived  from  the  internal  pudic, 
follow  the  course  of  their  corresponding  arteries,  and  give  off 
similar  branches.  They  not  only  supply  the  skin  of  the  perineum 
and  scrotum,  but  each  of  the  perineal  muscles. 


FIG,  89. 


Triangular  liga- 
ment .  .  . 

Tendinous  centre 
of  the  perineum 

Transversus  peri- 
nei  . 


I?chio-rectal  fossa 


Inferior  puden- 
da! n. 


Transversalis 
perinei  a. 

Snperflcialis 

perinei  a. 
External    hee- 

morrhoidal  a. 


MUSCLES,    "WITH    SUPERFICIAL   VESSELS    AND    NBKVES,    OF   THE    PERINEUM. 

The  inferior  pudendal  nerve,  a  branch  of  the  lesser  ischiatic, 
makes  its  exit  through  the  muscular  fascia  of  the  thigh,  a  little 
above  the  tuber  ischii.  It  ascends  nearly  parallel  to  the  ramus  of 
the  ischium  and  pubes,  and  dividing  into  filaments,  supplies  the 
skin  of  the  front  of  the  perineum  and  scrotum. 

E  K   2 


420  DISSECTION   OP   THE    MALE    PERINEUM. 

ACCELERATOR  This  muscle  embraces  the  bulb  of  the  urethra. 

UJUN^E.  It  arises  from  a  fibrous  median  raphe  beneath  the 

bulb,  and  from  the  tendinous  centre  of  the  perineum.  Starting 
from  this  origin,  the  fibres  diverge,  and  are  inserted  as  follows : — 
The  upper  ones  proceed  on  either  side  round  the  corpus  caver- 
nosum  penis,  like  the  branches  of  the  letter  V,  and  are  fixed  on  its 
dorsal  surface  ;  the  middle  completely  embrace  the  bulb,  like  a 
ring,  and  meet  in  an  aponeurosis  on  the  upper  surface  of  the 
urethra  ;  the  lower  are  fixed  to  the  anterior  surface  of  the  deep 
perineal  fascia,  often  called  the  triangular  ligament  (fig.  90).* 

FIG.  90. 


Corpus  cavernosum  .    .    . 
Corpus  spongiosum   .    .    . 


Upper  fibres 


Middle  fibres 


Lower  fibres 

Tendinous  centre  of    peri 
iieum 

DIAGRAM   TO    SHOW   THE   ACCELERATOR    URIN.ZE    IN   PROFILE. 

Thus,  the  entire  muscle  acts  as  a  powerful  compressor  of  the 
bulb,  and  expels  the  last  drops  of  urine  from  this  part  of  the 
urethra.  By  dividing  the  muscle  along  the  middle  line  and 
turning  back  each  half,  its  insertion,  as  above  described,  can  be 
clearly  made  out.f 

EKECTOB  This  muscle  is  moulded  upon  the  eras  of  the 

PENIS,  penis.     It   arises  from  the  inner  surface  of  the 

tuber  ischii ;  the  fibres  ascend,  completely  covering  the  crus,  and 

*  This  muscle  is  called  also  the  ejaculator  urina  or  the  bulbo-cavrenosus. 
j-  According  to  Hobelt,  the  dorsal  insertion  of  the  upper  fibres  throws  a  prolonga- 
tion over  the  dorsal  vessels  of  the  penis. 


DISSECTION    OF    THE    MALE    PERINEUM. 


421 


terminate  on  a  strong  aponeurosis,  which  is  inserted  into  the  ex- 
ternal and  inferior  aspect  of  the  crus.  The  action  of  this  muscle 
is  to  compress  the  root  of  the  penis,  and  so  to  contribute  to  the 
erection  of  the  organ.* 

FIG.  91. 


Crus  penis 


Crus  penis  with  its  ar- 
tery cut  through  .    . 


Ramus  of  the  ptibes 

Artery  of  the  bulb  . 
Cowper's  gland  .  . 
Pudic  artery  .  .  . 

Tuber  ischii     . 


DIAGRAM    TO    SHOW   THE   TRIANGULAR   LIGAMENT    OF   THE   URBTHBA 
OR   DEEP   PER1NEAL   FASCIA. 


TRANSYERSCS 
PERINEI. 


This  muscle  is  of  insignificant  size,  and  some- 
times absent.     It  arises  from  the  inner  aspect  of 
the  tuber  ischii,  and  proceeds  forwards  and  inwards  towards  the 
*  This  muscle  is  sometimes  called  the  ischio-cavmiosus. 


422  DISSECTION   OF   THE    MALE    PERINEUM. 

central  point  of  the  perineum,  where  it  is  blended  with  the  fibres 
of  the  accelerator  urinse.  This  muscle  with  its  artery  is  divided 
in  lithotomy. 

The  deep  transversus  perinei  is  a  small  muscle  occasionally 
present ;  it  arises  more  deeply  from  the  pubic  arch  than  the  super- 
ficial muscle,  and  passes  inwards  behind  the  bulb,  to  the  central 
tendon. 

The  next  stage  of  the  dissection  consists  in  reflecting  and  re- 
moving the  accelerator  urinse  from  the  bulb  of  the  urethra,  the 
erectores  penis  with  the  crura  penis  from  the  rami  of  the  pubes 
and  ischium,  and  the  transversi  perinei  muscles.  This  done,  the 
triangular  ligament  or  deep  perineal  fascia  is  fairly  exposed. 

TRIANGULAR  Understand  that  the  triangular  ligament  of  the 

LIGAMENT  OF  THE     urethra  and  the  deep  perineal  fascia  are  synony- 

URETHRA.  moUS  terms. 

The  triangular  ligament,  shown  in  fig.  91,  is  a  strong  fibrous 
membrane  stretched  across  the  pubic  arch.  It  is  about  an  inch 
and  a  half  long,  with  the  base  directed  backwards.  It  consists 
of  two  layers,  an  anterior  and  a  posterior.  The  anterior 
layer  is  firmly  attached  on  each  side  to  the  posterior  lip  of 
the  rami  of  the  pubes  and  ischium;  superiorly — i.e.  towards 
the  symphysis  of  the  pubes — it  is  connected  with  the  sub-pubic 
ligament  ;  inferiorly,  it  does  not  present  a  free  border,  but  is 
connected  to  the  tendinous  centre  of  the  perineum,  and  is  con- 
tinuous with  the  deep  layer  of  the  superficial  perineal  fascia  which 
curves  backwards  under  the  transversus  perinei  muscle  (p.  417). 

The  anterior  layer  of  the  triangular  ligament  is  perforated 
about  one  inch  below  the  symphysis  pubis,  for  the  membranous 
part  of  the  urethra.  The  aperture  through  which  the  urethra 
passes  does  not  present  a  distinct  edge,  because  the  ligament  is 
prolonged  forwards  over  .the  bulb,  and  serves  to  keep  it  in 
position. 

The  posterior  layer  cannot  at  present  be  seen.  It  belongs, 
strictly  speaking,  to  the  pelvic  fascia,  and  slopes  somewhat  back- 
wards from  the  anterior  layer  so  as  to  leave  an  interval  between 
them  in  which  are  found  structures  which  will  be  presently  described. 


DISSECTION    OF    THE    MALE    PERINEUM. 


423 


POINTS  OF  SUB-         The    triangular   ligament    is    very   important 
GICAL  INTEREST.        surgically  for  these  reasons  : — 

1.  Here  we  meet  with  difficulty  in  introducing  a  catheter, 
unless  we  can  hit  off  the  right  track  through  the  ligament.    The 

FIG.  92. 


Compressor  urethras  .    . 

Membranous  part  of  the 
urethra  surrounded  by 
its  compressor  muscle. 

Prostate  gland  .... 

Anterior  fibres  of  the  le- 
vatorani  . 


DIAGRAM   OP   THE   PARTS    BEHIND    THE   ANTERIOR   LATER   OF   THE    TRIANGULAR 
LIGAMENT   OF   THE    URETHRA. 

(The  anterior  fibres  of  the  levator  ani  are  hooked  down  to  show  part  of  the  prostate  ; 
the  rest  is  tracked  by  a  dotted  line.) 

soft  and  spongy  tissue  of  the  bulbous  part  of  the  urethra  in  front 
of  the  ligament  readily  gives  way,  if  force  be  used,  and  a  false 
passage  results. 


424  DISSECTION   OF   THE    MALE    PERINEUM. 

2.  By  elongating  the  penis,  we  are  much  more  likely  to  hit  off 
the  proper  opening  through  the  ligament. 

3.  When,  in  retention  of  urine,  the  urethra  gives  way  anterior 
to  this  ligament,  it  is  this  which  prevents  the  urine  from  travel- 
ling into  the  pelvis.     Its   connection  with  the  superficial  perineal 
fascia  prevents  the  urine  from  getting  into  the  ischio-rectal  fossae : 
nor  can  the  urine  make  its  way  into   the  thighs.     The  only  outlet 
for  it  is  into  the  connective  tissue  of  the  scrotum  and  penis. 

4.  When   suppuration  or  extravasation  of  urine  takes  place 
behind  the  ligament,  the  pus  is  pent  up  and  should  be  speedily 
let  out ;  if  not,  it  may  find  its  way  into  the  connective  tissue  of 
the  pelvis,  and  may  burst  into  the  urethra  or  the  rectum. 

5.  The  ligament  is  partially  cut  through  in  lithotomy. 

PARTS  DIVIDED  The  parts  divided  in  the  lateral  operation  of 
IN  LATERAL  lithotomy  are  :  the  skin,  the  superficial  fascia,  the 

LITHOTOMY.  transverse  perineal  muscle  vessels  and  nerve,  the 

inferior  haemorrhoidal  vessels  and  nerves,  the  inferior  fibres  of  the 
accelerator  urinse,  the  anterior  fibres  of  the  levator  ani,  the  com- 
pressor urethras,  the  triangular  ligament  (anterior  layer),  the 
membranous  and  prostatic  parts  of  the  urethra,  and  a  small  portion 
of  the  prostate. 

PARTS  TO  BE  The  incision  in  lateral  lithotomy  should  not  be 

AVOIDED.  made  too  far  forwards,  for  fear  of  wounding  the 

artery  of  the  bulb ;  nor  too  far  inwards,  for  fear  of  injuring  the 
rectum ;  nor  too  far  outwards,  for  fear  of  cutting  the  pudic 
artery. 

c.  The  anterior  layer  of  the  triangular  ligament 

STRUCTURES  J  » 

BETWEEN  THE  must  now  be  cut  away  to  see  what  lies  between  its 

LAYERS  OF  THE  two  layers.  These  parts  are  shown  in  fig.  92  ; 
TRIANGULAR  namely  :  1,  the  membranous  part  of  the  urethra, 

surrounded  by,  2,  the  compressor  urethrae  muscle  ; 
3,  Cowper's  glands  ;  4,  the  pudic  artery  and  its  three  terminal 
branches,  i.e.  the  artery  of  the  bulb,  the  artery  of  the  crus,  and  the 
dorsal  artery  of  the  penis  ;  5,  the  pudic  nerve  and  its  branches. 

To  obtain  the  best  perineal  view  of  the  com- 
pressor urethrae  muscle,  cut  through  the  spongy 


DISSECTION    OP    THE    MALE    PERINEUM.  425 

part  of  the  urethra  about  three  inches  above  the  end  of  the  bulb, 
and  dissect  it  from  the  corpus  cavernosum.  Thus,  the  upper 
fibres  of  the  constrictor  will  be  exposed  ;  to  see  the  lower,  it  is 
only  necessary  to  raise  the  bulb.  The  most  perfect  view,  however, 
of  the  muscle  is  obtained  by  making  a  transverse  section  through 
the  rami  of  the  pubes,  so  as  to  get  at  the  muscle  from  above,  as 
shown  in  fig.  93. 

COMPBESSOB  OB  This  muscle  consists  of  transverse  fibres  which 
CONSTRICTOR  surround  and  support  the  urethra  in  its  passage 

URETHRJE.  beneath  the  pubic  arch.  It  arises  from  the  ramus 

of  the  pubes  on  either  side ;  from  thence  its  fibres  pass,  some 
above,  some  below  the  urethra,  along  the  whole  length  of  its 
membranous  part.  It  forms  a  complete  muscular  covering  for  the 
urethra  between  the  prostate  and  the  bulb.  It  is  chiefly  through 
its  agency  that  we  retain  the  urine.  This  muscle  is  the  chief 
cause  of  spasmodic  stricture  of  the  urethra.* 

COWPEK'S  These  small  glands  are  situated,  one  on  either 

GLANDS.  side,  immediately  behind  the  bulb  between  the 

two  layers  of  the  triangular  ligament,  in  the  substance  of  the 
compressor  urethrse.  Their  size  is  about  that  of  a  pea,  but  it 
varies  in  different  individuals.  They  are  compound  racemose 
glands,  consisting  of  several  lobules  firmly  connected  together 
by  cellular  and  some  muscular  tissue.  From  each  a  slender 
duct  runs  forwards,  and,  after  a  course  of  about  one  inch, 
opens  obliquely  into  the  floor  of  the  bulbous  part  of  the  urethra 
(fig.  90).  They  furnish  a  secretion  accessory  to  generation. 

PUDIC  AKTERY  The  pudic  artery  is  a  branch  of  the  anterior 
AND  ITS  division  of  the  internal  iliac.  It  leaves  the  pelvis 

through  the  great  ischiatic  notch,  above  the  ischiatic 
artery,  winds  round  the  spine  of  the  ischium,  re-enters  the  pelvis 
through  the  lesser  ischiatic  notch,  and  then  runs  along  the  inner 
side  of  the  tuber  ischii,  between  the  layers  of  the  obturator  fascia, 
up  towards  the  pubic  arch.  About  an  inch  and  a  half  above  the 

*  The  compressor  urethrse  was  first  accurately  described  and  delineated  by  Santo- 
rini  (septemdec.  tabulae),  and  afterwards  by  Muller  in  his  monograph  (Ueber  die  organ, 
Nerv.  der  manulich.  G-eschlechtsorgane). 


426 


DISSECTION    OF   THE    MALE    PEBINEUM. 


tuber  ischii,  the  trunk  of  the  pudic  artery  can  be  felt ;  but  we  can- 
not see  it,  nor  draw  it  out,  for  it  is  securely  lodged  in  a  fibrous 
canal  formed  by  the  obturator  fascia.  In  the  present  dissection 


FIG.  93. 


Catheter 


Dorsal  nerve  of  the  penis    _ 
Dorsal  artery  of  the  penis . 
Doraal  vein  of  the  penis    . 


Anterior   layer   of   trian- 
gular ligament .... 

Ramns  of  pnbes  cut  throug' 
Posterior   layer   of  trian- 
gular ligament :  part  of 
the  pelvic  fascia    .    .    . 


DIAGRAM    OF    THE    RELATIONS    OF    THE   COMPRESSOR   URETHEjE    SEEN    FROM   ABOVE. 

we  find  the  artery  between  the  two  layers  of  the  triangular  liga- 
ment, where  it  gives  off  its  three  chief  branches,  namely,  the 
artery  of  the  bulb  of  the  urethra,  the  artery  of  the  cms  penis,  and 
the  dorsal  artery  of  the  penis  (fig.  91). 


DISSECTION    OF    THE    MALE    PERINEUM.  427 

Taken  in  order,  the  branches  of  the  pudic  artery  are  as 
follows : — 

a.  The  external  hcemorrhoidal,  the  superficial  perineal,  and  the  trans- 
verse perineal  branches  have  already  heen  described  (pp.  417,  418). 

b.  The  artery  of  the  bulb  is  of  considerable  size,  and  passes  trans- 
versely  inwards;    it   runs   through   the   substance   of  the   compressor 
urethrse,  and  before  it  enters  the  bulb  divides  into  two  or  three  branches. 
It  also  sends  a  small  branch  to  Cowper's  gland.     From  the  direction  of 
this  artery  it  will  at  once  strike  the  attention  that  there  is  great  risk  of 
dividing  it  in  lithotomy.     If  the  artery  run  along  its  usual  level,  and 
the  incision  be  not  made  too  high  in  the  perineum,  then  indeed  it  is  out 
of  the  way  of  harm.     But,  supposing  the  reverse,   the  vessel  must  be 
divided.     This  deviation  from  the  normal  distribution  is  met  with  about 
once  in  twenty  subjects,  and  there  is  no  possibility  of  ascertaining  this 
anomaly  beforehand. 

c.  The   artery    of    the   crus    penis,  one   of  the   terminal  branches, 
ascends  for  a  short  distance  near  the  pubic  arch  and   soon  enters  the 
crus. 

d.  To  see  the  dorsal  artery  of  the  penis,  the  penis  should  be  dissected 
from  its  attachment  to  the  symphysis  pubis.     The  artery  can  be  traced 
upon  the  dorsum  of  the  penis  down  to  the  glans.     It  forms  a  complete 
arterial   circle   with   its   fellow   round   the   corona   glandis,    and   gives 
numerous  ramifications  to  the  papillae  on  the  surface. 

The  veins  corresponding  to  the  branches  of  the  pudic  artery 
terminate  in  the  pudic  vein,  with  the  exception  of  the  dorsal  vein 
of  the  penis.  This  runs  along  the  middle  of  the  dorsum  of  the 
penis,  and  passing  under  the  symphysis  pubis  opens  into  the 
prostatic  plexus. 

The  pudic  nerve  comes  from  the  sacral  plexus, 
PUDIC  NERYE.  .  r 

and  corresponds   both  in  its  course  and  branches 

with  the  artery.  It  gives  off  its  external  or  inferior  hsemorrhoidal, 
and  its  superficial  perineal  branches — a  small  one  to  the  bulb,  and 
another  to  the  crus  penis ;  but  the  main  trunk  of  the  nerve  runs 
with  the  artery  along  the  dorsum  of  the  penis  to  the  glans  (fig.  93). 
In  its  passage  it  supplies  the  integuments  of  the  penis,  and  sends 
one  or  two  branches  into  the  corpus  cavernosum.  This  part  of  the 
penis  also  receives  nerves  from  the  sympathetic  system. 


428  SIDE    VIEW    OF   THE    PELVIC    VISCERA. 

ISCHIO-RECTAL  This  is  the  deep  hollow,  on  each  side,  between 

FOSSA,  the  anus  and  the  tuber  ischii.     When  all  the   fat 

is  removed  from  it,  observe  that  it  is  lined  on  all  sides  by  fascia. 
Introduce  the  finger  into  it  to  form  a  correct  idea  of  its  extent  and 
boundaries.  Externally  it  is  bounded  by  the  tuber  ischii  and  the 
fascia  covering  the  obturator  internus  muscle  ;  internally r,  by  the 
rectum,  levator  ani  and  coccygeus  ;  posteriorly,  by  the  gluteus 
maximus ;  anteriorly,  by  the  transversus  perinei.  The  fossa  is 
crossed  by  the  external  hsemorrhoidal  vessels  and  nerves. 

These  deep  spaces  on  each  side  of  the  rectum  explain  the  great 
size  which  abscesses  in  this  situation  may  attain.  The  matter  can 
be  felt  only  through  the  rectum.  Nothing  can  be  seen  outside. 
Perhaps  nothing  more  than  a  little  hardness  can  be  felt  by  the  side 
of  the  anus.  These  abscesses  should  be  opened  early ;  else  they 
form  a  large  cavity,  and  may  burst  into  the  rectum,  and  result  in 
a  fistula. 


ANATOMY   OF    THE   SIDE   VIEW   OF   THE   PELVIC   VISCERA. 

To  obtain  a  side  view  of  the  pelvic  viscera,  the 

DISSECTION 

left  innominate  bone  should  be  removed  thus  : — 
Detach  the  peritoneum  and  the  levator  ani  from  the  left  side  of 
the  pelvis,  cut  through  the  external  iliac  vessels,  the  obturator 
vessels  and  nerve,  and  the  nerves  of  the  lumbar  plexus  ;  then 
saw  through  the  pubes  about  two  inches  external  to  the  sym- 
physis,  and  cut  through  the  sacro-iliac  symphysis;  now  draw 
the  legs  apart,  and  saw  through  the  base  of  the  spine  of  the 
ischium  ;  after  cutting  through  the  pyriformis,  the  great  sacro- 
ischiatic  ligament  and  ischiatic  nerves,  the  innominate  bone 
can  be  easily  detached.  This  done,  the  rectum  should  be 
distended  with  tow,  and  the  bladder  blown  up  through  the  ureter. 
A  staff  should  be  passed  through  the  urethra  into  the  bladder,  and 
a  block  placed  under  the  sacrum. 

The  reflection  of  the  peritoneum  as  it  passes  from  the  front  of 
the  rectum  to  the  lower  part  of  the  bladder  (forming  the  recto- 
vesical  pouch),  and  thence  over  the  back  of  the  bladder  to  the  wall 


SIDE    VIEW    OP    THE    PELVIC    VISCERA. 


of  the  abdomen,  has  been  already  described.     You  see  where  the 
distended  bladder  is  bare  of  peritoneum,  and  that  it  can  be  tapped 
either  through  the  rectum  or  above  the  pubes  without  injury  to 
the  serous  membrane,  as  shown  by  the  arrows  in  fig.  94. 
FALSE  LIGA-  ^ne  peritoneal  connections  of  the  bladder  are 

called  its  false  ligaments  ;  false  in  contradistinc- 
tion to  the  true,  which  are  formed  by  the  fascia  of 

FIG.  94. 


Peritoneum  in  dot- 
ted outline    .    . 


MENTS  OF  THE 
BLADDER. 


Bulb  of  the  urethra 

Cowper's        gland 
with  duct  . 


Prostate    .    .     .    . 


VERTICAL   SECTION   THROUGH    THE   PERINEUM   AND    PELVIC   VISCERA. 

(The  arrows  point  out  where  the  bladder  can  be  tapped.) 

the  pelvis,  and  really  do  sustain  the  neck  of  the  bladder  in  its 
proper  position.  The  false  ligaments  are  five  in  number,  two 
posterior,  two  lateral,  and  one  superior.  The  posterior  are  produced 
by  two  peritoneal  folds,  one  on  either  side  the  recto-vesical  pouch  ; 
the  two  lateral,  by  reflections  of  the  peritoneum  from  the  sides  of 
the  pelvis  to  the  sides  of  the  bladder ;  the  superior  is  produced  by 


430 


SIDE    VIEW   OF    THE    PELVIC    VISCEEA. 


the  passage  of  the  peritoneum  from  the  front  of  the  bladder  to  the 
abdominal  wall. 

To  expose  the  pelvic  fascia,  the  peritoneum 
must  be  removed  from  that  side  of  the  pelvis 
which  has  not  been  disturbed :  in  doing  so,  notice  the  abundance 
of  loose  connective  tissue  interposed  between  the  peritoneum  and 


PELVIC  FASCIA. 


FIG.  95. 


Iliac  fascia 
covei-ing  ilia- 
cus  internus. 


Pelvic  fascia 
dividing. 

Obturator  fascia 
covering  obtu- 
rator internus. 

Becto-vesical 
layer  covering 
levator  ani. 


Anal  fascia 


TRANSVERSE    SECTION   OF   THE    PELVIS,    TO    SHOW    THE    REFLECTIONS    OF 

THE  PELVIC  FASCIA.     (After  Gray.) 

the  fascia,  to  allow  the  bladder  to  distend  with  facility.  When- 
ever urine  is  extravasted  into  this  loose  tissue,  it  is  sure  to  pro- 
duce the  most  serious  consequences ;  therefore  in  all  operations  on 
the  perineum,  it  is  of  the  utmost  importance  not  to  injure  this 
fascia. 


SIDE    VIEW    OP    THE    PELVIC    VISCERA.  431 

The  pelvic  fascia  is  a  thin  but  strong  membrane,  and  constitutes 
the  true  ligaments  of  the  bladder,  and  the  other  pelvic  viscera, 
supporting  and  maintaining  them  in  their  proper  position. 

Examine,  first,  to  what  parts  of  the  pelvis  the  fascia  is  attached ; 
secondly,  the  manner  in  which  it  is  reflected  on  the  viscera. 

Beginning,  then,  in  front  (fig.  95),  the  fascia  is  attached 
superiorly  to  the  body  of  the  pubes,to  the  side  of  the  pelvis  just  above 
the  obturator  foramen,  and  to  the  greater  ischiatic  notch.  Here 
it  becomes  gradually  thinner,  covers  the  pyriformis  muscle  and  the 
sacral  plexus,  and  is  lost  on  the  sacrum.  From  this  attachment  the 
fascia  descends  as  far  as  a  line  drawn  from  the 'spine  of  the  ischium 
to  the  symphysis  pubis.  Along  this  line,  which  corresponds  with 
the  origin  of  a  considerable  portion  of  the  levator  ani,  the  fascia 
divides  into  two  layers,  an  inner,  called  the  recto-vesical  fascia ; 
an  outer,  called  the  obturator  fascia. 

The  obturator  fascia,  the  outer  layer  of  the  pelvic  fascia, 
descends  on  the  inner  surface  of  the  obturator  internus,  forming, 
at  the  same  time,  a  sheath  for  the  pudic  vessels  and  nerve,  the 
nerve  being  the  lowest.  It  is  attached  to  the  arch  of  the  pubes, 
and  to  the  tuberosities  of  the  ischia.  From  this  fascia  is  derived 
the  anal  fascia.!  which  lines  the  under  or  permeal  surface  of  the 
levator  ani,  and  is  subsequently  lost  upon  the  side  of  the  rectum. 

The  recto-vesical  fascia  is  the  continuation  of  the  pelvic  fascia, 
and  descends  on  the  upper  or  internal  surface  of  the  levator  ani  to 
the  bladder  and  prostate.  From  the  pubes  it  is  reflected  over  the 
prostate  and  the  neck  of  the  bladder,  to  form,  on  either  side  of  the 
symphysis,  two  well-marked  bands — the  anterior  true  ligaments 
of  the  bladder.  From  the  side  of  the  pelvis  it  is  reflected  on  to 
the  side  of  the  bladder,  constituting  the  lateral  true  ligaments  of 
the  bladder,  and  incloses  the  prostate  and  the  vesical  plexus  of 
veins.  A  prolongation  from  this  ligament  incloses  the  vesicula 
seminalis,  and  then  passes  between  the  bladder  and  the  rectum,  to 
join  its  fellow  from  the  opposite  side. 

GENERAL  The  pelvic  viscera  are  so  surrounded  by  veins 

OSITIONOF TH        an(j  iooge  areoiar  tissue,  that  he  who  dissects  them 

IN  THE  MALE.           f°r  the  first  time  will  find  a  difficulty  in  discovering 


432  SIDE    VIEW   OF   THE    PELVIC    VISCERA. 

their  definite  boundaries.  The  rectum  runs  at  the  back  "of  the 
pelvis,  and  follows  the  anterior  curve  of  the  sacrum  and  coccyx. 
The  bladder  lies  in  front  of  the  rectum,  immediately  behind  the 
symphysis  pubis.  At  the  neck  of  the  bladder  is  the  prostate  gland 
through  which  the  urethra  passes.  In  the  cellular  tissue,  between 
the  bladder  and  the  rectum,  there  is,  on  each  side,  a  convoluted 
tube,  called  the  vesicula  seminalis,  and  on  the  inner  side  of  each 
vesicula  is  the  seminal  duct  or  vas  deferens.  Before  describing 
these  parts  in  detail,  it  is  necessary  to  say  a  few  words  about  the 
large  tortuous  veins  which  surround  them. 

Beneath  the  pelvic  fascia  surrounding  the  pros- 

PLEXUS  OF 

VEINS  ABOUT  tate  and  the  neck  of  the  bladder  are  large  and 

PBOSTATK  AND  tortuous  veins,  which  form  the  prostatic  and  the 
NECK.  OP  vesical  plexuses.  They  empty  themselves  into  the 

internal  iliac.  In  early  life  they  are  not  much 
developed,  but  as  puberty  approaches  they  gradually  increase  in 
size,  and  one  not  familiar  with  the  anatomy  of  these  parts  would 
hardly  credit  the  size  which  they  sometimes  attain  in  old  persons. 
They  communicate  freely  with  the  inferior  hsemorrhoidal  plexus, 
or  veins  about  the  anus,  and  they  receive  the  blood  returning 
from  the  penis  through  the  large  veins  which  pass  under  the  pubic 
arch. 

If,  in  lithotomy,  the  incision  be  carried  beyond  the  limits  of 
the  prostate,  the  great  veins  around  it  must  necessarily  be  divided  ; 
these,  independently  of  any  artery,  are  quite  sufficient  to  occasion 
serious  haemorrhage. 

KECTUM  AND  The  intestinum  rectum  is  about  eight  inches 

ITS  EELATIONS.  long.  It  is  a  continuation  of  the  sigmoid  flexure 
of  the  colon,  enters  the  pelvis  at  the  left  sacro-iliac  articulation, 
describes  a  curve  corresponding  to  the  sacrum,  and  terminates 
at  the  anus.  Before  its  termination,  the  bowel  turns  downwards 
so  that  the  anal  aperture  is  dependent.  The  rectum  also  inclines 
from  the  left  side  to  the  middle  line,  and,  although  it  loses  the 
sacculated  appearance,  is  not  throughout  of  equal  calibre.  Its 
capacity  becomes  greater  as  it  descends  into  the  pelvis ;  and, 
immediately  above  the  sphincter,  it  presents  a  considerable  dila- 


SIDE    VIEW    OF    THE    PELVIC    VISCEEA. 


433 


tation  (fig.  94).  This  dilatation  is  not  material  in  early  life,  but 
it  increases  as  age  advances.  Under  such  circumstances  the 
rectum  loses  altogether  its  cylindrical  form,  and  bulges  up  on 
either  side  of  the  prostate  and  the  base  of  the  bladder.  For 
this  reason  the  rectum  should  always  be  emptied  before  the  opera- 
tion of  lithotomy. 

FIG.  96. 


SIDE   VIEW   OF   THE    PELVIC   VISCEBA. 

(Taken  from  a  Photograph.) 

1.  External  sphincter. 

2.  Internal  sphincter. 

8.  Levator  ani  cut  through. 

4.  Accelerator  urinse. 

5.  Membranous  part  of  the  urethra,  sur- 

rounded by  compressor  muscle. 

6.  Prostate  gland. 


7.  Vesicula  seminalis. 

8.  Ureter. 

9.  Vas  deferens. 

10.  Crus  penis  divided. 

11.  Triangular  ligament. 

12.  Superficial  perineal  fascia. 

13.  Kectum. 


The  upper  part  of  the  rectum  (for  about  three  inches  and  a 
half)  is  connected  to  the  sacrum  by  a  fold  of  peritoneum  termed 

F  F 


434  SIDE    VIEW   OF   THE    PELVIC    VISCERA. 

mesa-rectum.  In  this  fold,  the  terminal  branch  of  the  inferior 
mesenteric  artery  with  its  vein  runs  up  to  supply  the  bowel.  Below 
the  meso-rectum,  the  intestine  is  connected  posteriorly  to  the 
sacrum  and  coccyx  by  loose  connective  tissue,  and  is  covered  by 
peritoneum  in  front,  which  forms  the  recto-vesical  pouch.  The 
lower  three  inches  and  a-half  are  entirely  destitute  of  peritoneum. 
The  rectum  is  supported  by  the  levatores  ani,  the  larger  portions 
of  which  are  inserted  into  its  side. 

DIGITAL  The  relations  of  the  front  part  of  the  rectum — 

EXAMINATION  OF  that,  namely,  included  between  the  recto-vesical 
THE  RECTUM.  pouch  and  the  anus — are  most  important.  If  the 

forefinger  be  introduced  into  the  anus,  and  a  catheter  into  the 
urethra,  the  first  thing  felt  through  the  front  wall  of  the  bowel  is 
the  membranous  part  of  'the  urethra  (fig.  94).  It  lies  just  within 
the  sphincter,  and  is  about"  ten  lines  in  front  of  the  gut.  About 
one  and  a  half  or  two  inches  from  the  anus  the  finger  comes  upon 
the  prostate  gland ;  this  is  in  close  contact  with  the  gut,  and  is 
readily  felt  on  account  of  its  hardness  ;  by  moving  the  finger  from 
side  to  side  we  recognise1  its  lateral  lobes.  Still  higher  up,  the 
finger  goes  beyond  the  prostate,  and  reaches  the  trigone  of  the 
bladder :  the  facility  with  which  this  can  be  examined  depends, 
not  only  upon  the  length  of  the  finger  and  the  amount  of  fat  in 
the  perineum,  but  upon  the  degree  of  distension  of  the  bladder ; 
the  more  distended  the  bladder,  the  better  can  the  prostate  be' 
felt.  These  several  relations  are  practically  important.  They 
explain  why,  with  the  finger  in  the  rectum,  we  can  ascertain 
whether  the  catheter  is  taking  the  right  direction — whether  the 
prostate  be  enlarged  or  not.  We  might  even  raise  a  stone  from 
the  bottom  of  the  bladder- so  as  to  bring  it  in  contact  with  the 
forceps. 

The  rectum  is  supplied  with  blood  by  the  superior,  middle, 
and  inferior  hsemorrhoidal  arteries.  The  superior  comes  from 
the  inferior  mesenteric  (p.  392)  ;  the  middle  and  inferior  from 
the  pudic  artery.  The  superior  and  middle  haemorrhoidal  veins 
join  the  inferior  mesenteric,  and  consequently  the  portal  system  ; 
the  inferior  haemorrhoidal  veins  join  the  internal  pudic.  They  are 


SIDE    VIEW    OP    THE    PELVIC    VISCEKA. 


435 


BLABBER. 


very  large  and  form  loop-like  plexuses  about  the  lower  part 
of  the  rectum.  Having  no  valves,  they  are  liable  to  become 
dilated  and  congested  from  various  internal  causes  ;  hence  the 
frequency  of  haemorrhoidal  affections. 

This  viscus,  being  a  receptacle  for  the  urine, 
must  necessarily  vary  in  size,  and  accordingly  the 
nature  of  its  connections  and  coats  are  such  as  to  permit  this 
variation.  When  contracted,  the  bladder  sinks  into  the  pelvis 
behind  the  pubic  arch,  and  is  completely  protected  from  injury. 
But,  as  it  gradually  distends,  it  rises  out  of  the  pelvis  into  the 
abdomen,  and,  in  cases  of  extreme  distension,  may  reach  nearly  up 

FIG.  97. 


1.  Ureter. 

2.  Vas  deferens. 


3.  Vesicula  seminalis. 

4.  Trigone. 

5.  Prostate. 


POSTERIOR   VIEW    OF   THE   BLABBER. 

to  the  umbilicus.*     Its  outline  can  then  be  easily  felt  through  the 
walls  of  the  abdomen.     The  form  f  of  the  distended  bladder  is 

*  "When  the  bladder  is  completely  paralysed  it  becomes  like  an  inorganic  sac,  and 
there  seems  to  be  no  limit,  to  its  distension.  Haller  found,  in  a  drunkard,  the  bladder 
so  dilated  that  it  would  hold  twenty  pints  of  water.  ('  Elem.  Phys.  art.  Vesica.') 
Frank  saw  a  bladder  so  distended  as  to  resemble  ascites,  and  evacuated  from  it  twelve 
pounds  of  urine.  (Oratio  de  Signis  morborum,  &c.  &c.  Ticiui,  1788.) 

W.  Hunter,  in  his  '  Anatomy  of  the  Gravid  Uterus,'  has  given  the  representation 
of  a  bladder  distended  nearly  as.  high  as  the  ensiform  cartilage. 

f  In  all  anim.'ils  with  a  bladder,  the  younger  the  animal  the  more  elongated  is  the 
bladder.  This  is  indicative  of  its  original  derivation  from  a  tube,  i.e.  the  urachus. 
In  the  infant,  the  bladder  is  of  a  pyriform  shape,  as  it  is,  permanently,  in  the  quad- 
ruped ;  but  as  we  assume  more  and  more  the  perpendicular  attitude,  the  weight  of  the 
urine  gradually  makes  the  lower  part  more  capacious. 

F  F  2 


436  SIDE    VIEW    OF    THE    PELVIC    VISCERA. 

oval,  and  its  long  axis,  if  produced,  would  pass  superiorly  through 
the  umbilicus,  and  inferiorly  through  the  end  of  the  coccyx.  The 
axis  of  a  child's  bladder  is  more  vertical  than  that  of  the  adult ; 
for  in  children,  the  bladder  is  not  a  pelvic  viscus.  This  makes 
lithotomy  in  them  so  much  more  difficult. 

The  quantity  of  urine  which  the  bladder  will  hold  without 
much  inconvenience  varies.  As  a  general  rule,  it  may  be  stated  at 
about  a  pint.  Much  depends  upon  the  habits  of  the  individual ; 
but  some  persons  have,  naturally,  a  very  small  bladder,  and  are 
obliged  to  empty  it  more  frequently. 

In  young  persons  the  lowest  part  of  the  bladder  is  the  neck, 
or  that  part  which  joins  the  prostate.  But  as  age  advances,  the 
bottom  of  the  bladder  gradually  deepens  so  as  to  form  a  pouch 
behind  the  prostate.  In  old  subjects,  particularly  if  the  prostate 
be  enlarged,  this  pouch  becomes  deep,  micturition  becomes  tedious, 
and  the  bladder  cannot  completely  empty  its  contents.  It  some- 
times happens  that  a  stone  in  the  bladder  is  not  felt ;  the 
reason  of  which  may  be  that  the  stone,  lodged  in  such  a  pouch 
below  the  level  of  the  neck  of  the  bladder,  escapes  the  detection  of 
the  sound.  Under  these  circumstances,  if  the  patient  be  placed 
on  an  inclined  plane  with  the  pelvis  higher  than  the  shoulders, 
the  stone  falls  out  of  the  pouch,  and  is  easily  struck. 

This  tube  is  about  seventeen  inches  long,  and 
conveys  the  urine  from  the  kidney  to  the  bladder. 
In  the  dissection  of  the  abdomen  (p.  394),  it  was  seen  descending 
along  the  psoas  muscle,  behind  the  spermatic  vessels,  and  crossing 
the  common  iliac  artery  into  the  pelvis.  Tracing  it  downwards, 
in  the  posterior  false  ligament  of  the  bladder,  we  find  that  it  runs 
along  the  side  of  the  bladder,  external  to  the  vas  deferens,  and 
enters  it  about  an  inch  and  a  half  behind  the  prostate,  and  about 
two  inches  from  its  fellow  of  the  opposite  side  (fig.  97).  It  per- 
forates the  bladder  very  obliquely,  so  that  the  aperture,  being 
valvular,  allows  the  urine  to  flow  into,  but  not  out  of  it.  The 
narrowest  part  of  the  ureter  is  at  the  vesical  orifice  ;  here,  there- 
fore, a  calculus  is  more  likely  to  be  arrested  in  its  progress  than 
at  any  other  part  of  the  canal. 


SIDE    VIEW    OF    THE    PELVIC    VISCERA.  437 

This  tube,  about  twenty-four  inches  in  length, 

\  AS  DEFEEKNS 

conveys  the  seminal  fluid  from  the  testicle  into 
the  prostatic  part  of  the  urethra.  It  ascends  at  the  back  part 
of  the  spermatic  cord  through  the  inguinal  canal  into  the  abdo- 
men ;  then,  leaving  the  cord  at  the  inner  ring,  it  curves  round 
the  epigastric  artery,  then  crosses  over  the  external  iliac  vessels, 
and  descends  into  the  pelvis  on  the  side  of  the  bladder,  gradually 
approaching  nearer  the  middle  line.  Before  it  reaches  the  prostate 
it  passes  between  the  bladder  and  the  ureter ;  then,  becoming  very 
tortuous,  it  runs  internal  to  the  vesicula  seminalis,  and  is  joined 
by  the  duct  of  this  vesicle.  The  common  duct  thus  formed, 
ductus  communis  ejaculatorius,  terminates  in  the  lower  part  of 
the  prostatic  portion  of  the  urethra  (fig.  97,  p.  435).  In  point 
of  size  and  hardness,  the  vas  deferens  has  very  much  the  feel  of 
whipcord.* 

These  are  situated,  one  on  either  side,  between 
the  bladder  and  the  rectum  (fig.  96).  Each  is 
a  tube,  but  so  convoluted  that  it  is  like  a  little  sacculated 
bladder.  When  rolled  up,  the  tube  is  about  two  and  a  half  inches 
long ;  unrolled,  it  would  be  more  than  twice  that  length,  and 
about  the  size  of  a  small  writing  quill.  Several  caecal  prolonga- 
tions proceed  from  the  main  tube,  after  the  manner  of  a  stag's 
horn.  The  vesiculaB  seminales  do  not  run  parallel,  but  diverge 
from  each  other,  posteriorly,  as  far  as  the  reflection  of  the  recto- 
vesical  peritoneal  pouch,  like  the  branches  of  the  letter  V ;  and 
each  lies  immediately  on  the  outer  side  of  the  vas  deferens,  into 
which  it  opens.  The  vesiculse  seminales  probably  serve  as  reser- 
voirs for  the  semen. 

They   contain   a   brownish-coloured  fluid,  presumed  to  be  in 
some  way  accessory  to  the  function  of  generation,  f 

*  The  description  in  the  text  assumes  the  bladder  to  be  distended.  But  when 
the  bladder  is  empty  the  vas  deferens  runs  down  upon  the  side  of  the  pelvis.  In 
this  course  it  may  be  seen,  through  the  peritoneum,  crossing — 1,  the  external  iliac 
vessels  ;  2,  the  remains  of  the  umbilical  artery  ;  3,  the  obturator  artery  and  nerve  ; 
4,  the  ureter. 

t  The  vesiculae  seminales  are  imperfectly  developed  till  the  age  of  puberty.  In  a 
child  of  three  years  of  age  they  can  hardly  be  inflated  with  the  blowpipe. 


438  SIDE    VIEW    OF    THE    PELVIC    VISCEKA. 

PEOSTATE  The  prostate  gland  is  situated  at  the  neck  of 

GLAND>  the  bladder,  and  surrounds  the  first  part  of  the 

urethra  (fig.  96).  In  the  healthy  adult  it  is  about  the  size  and 
shape  of  a  chestnut.  Its  apex  is  directed  forwards.  It  is  sur- 
rounded by  a  plexus  of  veins  (p.  432),  and  is  maintained  in  its 
position  by  the  pelvic  fascia  (p.  431).  Its  upper  surface  is  about 
three-quarters  of  an  inch  below  the  symphysis  pubis :  its  apex  is 
about  one  inch  and  a  half  from  the  anus;  the  base  is  about  two 
and  a  half. 

Above  the  prostate  are  the  anterior  ligaments  of  the  bladder, 
with  the  dorsal  vein  of  the  penis  between  them ;  below,  and  in 
contact  with  it,  is  the  rectum ;  on  each  side  of  it  is  the  levator 
ani ;  in  front  of  it  are  the  membranous  part  of  the  urethra  (sur- 
rounded by  its  compressor  muscle),  and  the  triangular  ligament ; 
behind,  are  the  neck  of  the  bladder  and  the  vesiculae  seminales 
with  the  ejaculatory  ducts. 

The  transverse  diameter  is  about  one  inch  and  a  half;  the 
vertical  is  about  half  an  inch  less.  But  the  gland  varies  in  size 
at  different  periods  of  life.  In  the  child  it  is  imperfectly  de- 
veloped :  it  gradually  grows  towards  puberty,  and  generally  in- 
creases in  size  with  advancing  age. 

To  ascertain  the  size  and  condition  of  the  prostate  during  life, 
the  bladder  should  be  at  least  half  full :  the  prostate  is  then 
pressed  down  towards  the  rectum,  and  readily  within  reach  of  the 
finger. 

The   urethra  is  a  canal  about  eight  inches  in 
ANATOMY  OF 

THE  UEETHEA  length,  and  leads  from  the  bladder  to  the  end  of 
IN  ITS  PASSAGE  the  penis.  It  is  divided  into  three  portions — the 
prostatic,  the  membranous,  and  the  spongy.  At 
present  only  the  relations  of  the  membranous 
part,  which  comprises  that  part  of  the  canal  between  the 
prostate  and  the  bulb,  can  be  examined.  The  urethra  in  this 
part  is  nearly  one  inch  in  length,  but  longer  on  its  upper 
than  its  lower  surface,  in  consequence  of  the  encroachment 
of  the  bulb.  In  its  passage  under  the  arch  of  the  pubes,  it  is 
surrounded  by  the  compressor  urethras,  and  below  it  are  Cowper's 


SIDE    VIEW    OF    THE    PELVIC    VISCERA.  439 

glands.  It  traverses  the  two  layers  of  the  triangular  ligament, 
and  is  about  an  inch  below  the  symphysis  pubis,1  and  nearly  the 
same  distance  from  the  rectum;, it  is  not,  however,  equidistant 
from  this  portion  of  the  intestine  at  all  points,  because  of  the 
downward  bend  which  the  rectum  makes  towards  the  anus.* 

The  membranous  part  of  the  urethra  in  children  is  very  long, 
owing  to  the  smallness  of  the  prostate  at  that  period  of  life  ;  it 
is  also  composed  of  thin  and  delicate  walls,  and  lies  close  to  the 
rectum.  In  sounding  a  child,  therefore,  it  is  very  necessary  not 
to  use  violence^  else  the  instrument  is  likely  to- pass  through  the 
coats  of  the  urethra  and  make  a  false  passage. 

This  muscle  supports  the  anus  and  lower  part 
of  the  rectum  like  a  sling ;  and,  with  the  coccy- 
geus  and  compressor  urethrae,  forms  a  muscular  floor  for  the 
cavity  of  the  pelvis.  To  see  the  muscle,  the  pelvic  fascia  must  be 
reflected  from  its'  upper  surface.  It  arises  from  the  posterior 
aspect  of  the  pubes  near  the  symphysis,  from  the  spine  of  the 
ischium,  and,  between  these  bones,  from  the  tendinous  line  which 
marks  the  division  of  the  pelvic  fascia  into  the  obturator  and 
recto-vesical  layers  (p.  430).  From  this  long  origin  the  fibres 
descend  inwards,  and  are  inserted  thus — the  anterior,  passing 
under  the  prostate,  meet  their  fellow  in  the  middle  line  of  the 
perineum  in  front  of  the  anus  (forming  the  '  so-called '  levator 
prostatse) ;  the  middle  are  inserted  into  the  side  of  the  rectum, 
while  the  posterior  meet  their  fellow  beneath  the  rectum. 

The  levator  ani  is  supplied  by  the  inferior  rhsemorrhoidal,  the 
two  lower  sacral,  and  the  coccygeal  nerves, 

The  action  of  the  levatores  ani .  is  to  retract  the  anus  and  the 
rectum  after  it  has  been  protruded  in  defsecation  by  the  combined 
action  of  the  abdominal  muscles  and  the  diaphragm. 

This  muscle  should  be  regarded  as  a  continu- 
ation of  the  levator  ani.     It  arises  by  its  apex 
from  the  spine  of  the  ischium,  gradually,  spreads  out,  and  is  in- 

*  If  a  clean  vertical  section  -were  made,  we  should  see  that  the  two  canals  form 
the  sides  of  a  triangular  space,  of  which  the  apex  is  towards  the  prostate.  This  is 
sometimes  called  the  recto-urethral  triangle. 


440  SIDE    VIEW   OP   THE    PELVIC    VISCERA. 

serted  into  the  side  of  the  sacrum  and  the  coccyx.  This  muscle 
is  supplied  by  the  two  lower  sacral  and  the  coccygeal  nerves. 

At  this  stage  of   the  dissection,  the  bladder 
should  be  drawn  downwards,  and  the  branches  of 
the  internal  iliac  artery  and  the  sacral  plexus  clearly  displayed. 

INTERNAL  From  the  division  of  the  common  iliac  artery, 

ILIAC  ABTEEY  the  internal  iliac  descends  into  the  pelvis,  and, 
AND  BRANCHES.  after  a  course  of  about  an  inch  and  a  half,  divides, 
opposite  the  great  sacro-ischiatic  notch,  into  two  large  branches, 
an  anterior  and  a  posterior  (fig.  98).  The  artery  lies  upon  the 


FIG. 


SAC  LAT 
PLAN    OF   THE    BRANCHES    OF    THE    INTERNAL    ILIAC. 

lumbo-sacral  cord,  the  pyriformis  muscle,  the  external  and 
internal  iliac  veins;  the  ureter,  enclosed  in  the  posterior  false 
ligament  of  the  bladder,  passing  in  front. 

The  posterior  division  gives  off  the  ilio-lumbar;  lateral  sacral, 
and  giuteal  arteries;  the  anterior  gives  off  the  superior  vesical, 
obturator,  inferior  vesical,  middle  h^morrhoidal,  isehiatic  and 
pudic;  also  the  uterine  and  vaginal  in  the  female.  Such  is  their 
usual  order;  but  these  branches,  though  constant  as  to  their 
general  distribution,  vary  as  to  their  origin. 

The  branches  of  the  posterior  division  are  — 

«.  The  ilio-lumbar  is  analogous  to  the  lumbar  branches  of  the 


SIDE    VIEW    OF    THE    PELVIC    VISCERA. 


441 


aorta.  It  ascends  beneath  the  psoas,  sends  branches  to  this 
muscle  and  the  quadratus  lumborum ;  then  running  near  the  crest 
of  the  ilium,  it  supplies  the  iliacus  internus,  and  finally  inoscu- 
lates with  the  deep  circumflexa  ilii  (fig.  98). 

6.  The  lateral  sacral,  usually  two  in  number,  descend  in  front 
of  the  sacral  foramina,  and  inosculate  on  the  coccyx  with  the 
middle  sacral  artery.  They  give  branches  to  the  pyriformis,  the 
bladder,  and  rectum,  and  others  which  enter  the  anterior  sacral 
foramina  for  the  supply  of  the  cauda  equina. 

c.  The  gluteal  is  the  largest  branch.  It  passes  immediately 
out  of  the  pelvis  through  the  great  ischiatic  notch,  above  the  pyri- 

Fio.  99. 


YIEW    OF   THE    DIFFERENT    DIRECTIONS    WHICH    AN    ABNORMAL    OBDURATOR    ARTERY 

MAT  TAKE.     (Seen  from  above.) 


A.  1.  Gimbernat's  ligament. 

2.  Femoral  ring. 

3.  Abnormal  obturator  artery. 

4.  External  iliac  vein. 

5.  'External  iliac  artery. 

6.  Diminutive  obturator  artery  arising 

from  its  normal  source. 


B.  1.  Gimbernat's  ligament. 

2.  Abnormal  obturator  artery. 

3.  Femoral  ring. 

4.  External  iliac  vein. 

5.  External  iliac  artery. 

6.  Diminutive  obturator  artery. 


formis  muscle,  and  then  divides  into  branches  for  the  supply  of 
the  great  muscles  of  the  buttock.  These  will  be  dissected  with 
the  thigh. 

The  anterior  division  gives  off  — 

a.  The  superior  vesical  artery  comes  off  from  the  unobliterated 
portion  of  the  hypogastric,  and  supplies  the  upper  part  of  the 


442  SIDE    VIEW    OF   THE    PELVIC    VISCERA. 

bladder.    It  gives  off  the  middle  vesical  artery ;  and  a  still  smaller 
one,  the  deferential,  which  accompanies  the  vas  deferens. 

6.  The  inferior  vesical  artery  ramifies  on  the  under  surface  of 
the  bladder,  the  vesiculse  seminales  and  the  prostate,  and  gives  off 
the  middle  hoemorrhoidal  which  supplies  the  rectum. 

c.  The  obturator,  artery  runs  along  the  side  of  the-pelvis,  below 
the  corresponding  nerve,  to  the  upper  part  of  the  obturator  fora- 
men, through  which  it  passes  to  be  distributed  to  the  muscles  of 
the  thigh.     In  the  pelvis  it  lies  between  the  peritoneum  and  the 
pelvic  fascia,  and  gives  off  a  small  branch^to  the  iliacus  internus, 
and  another,  the  pubic.,  .whicb  ramifies  on  the  back  of  the  pubes. 

The  obturator  artery  does  not,  in  all  subjects,  take  the  course 
above  stated.  It  may  arise  from  the  external  iliac  near  the  crural 
arch,  or  by  a  short  trunk  in  common  with  the  epigastric.*  Under 
these  circumstances,  in  order  to  reach  the  obturator  foramen,  it 
generally  descends  on  the  outer  side  of  the  femoral  ring.  Instances 
however,  occasionally  occur,  where  it  makes  a  sweep  round  the 
inner  side  of  the  ring;  .so  that  three-fourths  of  the  ring,  or,  what 
comes  to  the  same  thing,  of  the  neck  of  a  femoral  hernia,  would 
in  such  a  case  be  surrounded  by  a  large  artery  .-f- 

d.  The  ischiatic  artery  is  smaller  than  the  gluteal.  It  proceeds 
over  the  pyriformis  and  the  sacral  plexus,  to  the  lower  border  of 
the  great  ischiatic  notch,  through  which  it  passes  out  of  the  pelvis 
to  the  buttock,  where  it  runs  with  the  great  ischiatic  nerve.     It 
gives  off  small  muscular  branches  in  the,  pelvis  to  the  pyriformis 
and  coccygeus. 

e.  The  pudic  artery  supplies  the  perineum,  scrotum  and  penis. 
In  the  pelvis  it  usually  lies  above  the  ischiatic,  and  rests  upon  the 

*  In  most  subjects  a  small  branch,  of  the  obturator  ascends  behind  the  ramus  of 
the  pubes  to  inosculate  with  the  epigastric.  The  variety  in  which  the  obturator  arises 
in  common  with  the  epigastric  is  but  an  unusual  development  of  this  branch.  The 
branch  derives  additional  interest  from  the  fact,  that  after  ligature  of  the  external 
iliac  it  becomes  greatly  enlarged,  and  carries  blood  directly  into  the  epigastric.  See  a 
case  in  'Med.  Chir.  Trans.'  vol.  xx.  1836. 

f  The  Museum  of  St.  Bartholomew's  Hospital  contains  two  examples  of  double 
femoral  hernise  in  the  male,  with  the  obturator  arising  on  each  side  from  the  epigastric. 
In  three  out  of  the  four  ruptures  the  obturator  runs  on  the  inner  side  of  the  mouth  of 
the  sac.  (See  Preparations  55,  69,  Series  17.) 


SIDE    VIEW    OF    THE    PELVIC    VISCERA.  443 

pyriformis  and  sacral  plexus,  having  the  rectum  to  its  inner  side. 
It  passes  out  of  the  pelvis  through  the  great  ischiatic  notch,  below 
the  pyriformis,  crosses  the  spine  of  the  ischium,  and  re-enters  the 
pelvis  through  the  lesser  notch.  It  then  ascends  on  the  inner  side 
of  the  obturator  internus  towards  the  pubic  arch,  where  it  gives 
branches  to  the  several  parts  of  the  penis.  In  its  passage  on  the 
inner  side  of  the  obturator  muscle  it  is  enclosed  in  a  strong  tube  of 
fascia  (formed  by  the  obturator  fascia),  and  is  situated  about  one 
inch  and  a  quarter  above  the  tuberosity  of  the  ischium.  The 
branches  of  the  pudic  artery  were  described  in  the  dissection  of  the 
perineum  (p.  425). 

The  pudic  artery,  however,  sometimes  takes  a  very  different 
course.  Instead  of  passing  out  of  the  pelvis,  it  may  run  by  the 
side  of  the  prostate  gland  to  its  destination;  or,  one  of  the  large 
branches  of  the  pudic  may  take  this  unusual  course,  while  the 
pudic  itself  is  regular,  but  proportionably  small.  Anatomists  are 
familiar  with  these  varieties,  and  a  winter  session  rarely  passes 
without  meeting  with  one  or  two  examples  of  them.  It  need 
hardly  be  said  that  lithotomy,  under  such  conditions,  might  be 
followed  by  a  large  haemorrhage. 

/.  The  middle  sacral  artery  is  a  very  diminutive  prolongation 
of  the  aorta  down  to  the  coccyx.  It  becomes  gradually  smaller, 
and  finally  inosculates  with  the  lateral  sacral  arteries.  In 
animals  this  is  the  artery  of  the  tail. 

Respecting  the  veins  in  the  pelvis,  they  correspond  with  the 
arteries,  and  empty  themselves  into  the  internal  iliac  vein.  The 
remarkable  plexus  of  veins  about  the  prostate,  neck  of  the  bladder, 
and  rectum,  has  been  described  (p.  432). 

NEBVESOFTHE         Those    which    proceed   from   the    spinal   cord 
PELVIS.  should   be   examined   first,  afterwards   those   de- 

rived from  the  sympathetic  system. 

SACEAL  Five  sacral  nerves  proceed  from  the  spinal  cord 

NERVES.  through  the  anterior  sacral  foramina.     The  upper 

four,  from  their  large  size,  at  once  attract  observation;  but  the 
fifth  is  small :  it  perforates  the  coccygeus  muscle,  supplying  it  and 
the  skin  over  the  coccyx. 


444 


SIDE    VIEW   OF    THE    PELVIC    VISCERA. 


The  lower  part  of  the  fourth  sacral  nerve  does  not  form  part 
of  the  plexus ;  it  gives  off  branches  to  the  pelvic  organs,  and 
muscular  twigs  to  the  levator  ani,  coccygeus,  and  the  external 
sphincter. 

The  coccygeal  nerve,  not  easily  found,  pierces  the  great  sacro- 
ischiatic  ligament  and  coccygeus;  it  communicates  with  the  fifth 

Fro.  100. 


12.  N.  of  pyriformis. 

13.  N.  of  gemellus  superior. 

14.  N.  of  gemellus  inferior. 

15.  N.  of  quadratics  femoris. 

16.  N.  of  glutens  maximus. 

17.  Long  pudendal  n. 

18.  Cutaneous  n.  of  the  but- 

tock. 

19.  N.  of  the  long  head  of 

the  biceps. 

20.  N.  of  semi-tendinosus. 

21.  N.    of   semi-membrano- 

sus. 

22.  N.  of  short  head  of  the 

biceps. 


1,  2,  3,  4,  5.  Sacral  nn. 

6.  Superior  gluteal  n. 

7.  Great  ischiatic  n. 

8.  Lesser  ischiatic  n. 

9.  Pudic  n. 

10.  N.  of  obturator  internus. 

11.  N.  of  levator  ani. 


PLAN   OF   THE    SACRAL   PLEXUS    AND    BRANCHES. 

sacral  nerve,  and  supplies  the  same  parts  ;  namely,  the  coccygeus 
and  the  skin  over  the  coccyx. 

SACRAL  The  three  upper  sacral  nerves,  and  part  of  the 

PLEXUS.  fourth,   with   the    lumbo-sacral    cord,   form    the 

sacral  plexus.  The  great  nerves  of  the  plexus  lie  on  the  pyri- 
formis  muscle,  beneath  the  branches  of  the  internal  iliac  artery, 
and  coalesce  to  form  the  great  ischiatic  nerve,  which  passes  out  at 


SIDE    VIEW    OF    THE    PELVIC    VISCEEA.  445 

the  back  of  the  pelvis,  for  the  supply  of  the  flexor  muscles  of  the 
inferior  extremity.  The  other  branches  of  the  plexus  are  as 
follows : — 

a.  Muscular  branches  distributed  to  the  levator  ani,  the  coccy- 
geus,  the  external  sphincter  of  the  anus,  the  pyriformis,  gemelli, 
quadratus  femoris,  and  obturator  internus.     The  nerve  to  the  last- 
named   muscle  (sometimes  derived  from  the   pudic)   leaves  the 
pelvis  with  the  pudic  artery,  and  re-enters  with  it  to  reach  the 
muscle.     The  branch  to  the  inferior  gemellus  and  quadratus  fe- 
moris passes   beneath  those    muscles   and   enters   their   anterior 
aspect.     It  also  sends  a  filament  to  the  hip-joint. 

b.  The  superior  gluteal  nerve  proceeds  from  the  lumbo-sacral, 
leaves  the  pelvis  above  the  pyriformis  with  the  gluteal  artery,  and 
supplies  the  gluteus  medius  and  minimus,  and  the  tensor  fasciae 
femoris. 

c.  The  lesser  ischiatic  supplies  the  gluteus  maximus,  the  skin 
of  the  buttock,  the  perineum,  and  the  back  of  the  thigh. 

d.  The  pudic  nerve  runs  with  the  pudic  artery,  and  like  it, 
supplies  the  rectum,  the  muscles  of  the  perineum,  and  the  penis. 

e.  The  branches  for  the  pelvic  viscera  are  very  small.     They 
proceed  chiefly  from  the  third  and  fourth  sacral  nerves,  and  form 
an  intricate  plexus  about  the  bladder,  prostate,  and  rectum. 

SYMPATHETIC  From  the  lumbar  region  the  sympathetic  nerve 

NERVE.  descends  into  the  pelvis,  along  the  inner  side  of 

the  sacral  foramina.  In  this  part  of  its  course  its  ganglia  vary  in 
number  from  three  to  five.  The  nerves  of  opposite  sides  unite 
in  front  of  the  coccyx,  where  they  form  the  ganglion  impar. 

The  arrangement  of  the  sympathetic  nerves  in  the  pelvis  is 
similar  to  that  in  the  abdomen.  Each  ganglion  receives  one  or 
two  filaments  from  a  spinal  nerve,  and  then  gives  off  its  branches 
to  the  viscera.  The  visceral  branches  are  exceedingly  delicate, 
and  cannot  be  traced  unless  the  parts  have  been  previously 
hardened  in  spirit.  They  accompany  the  arteries  supplying  the 
respective  organs,  and  are  called  the  vesical,  prostatic,  and 
inferior  hcemorrhoidal  plexuses ;  and  in  the  female  the  uterine 
and  vaginal. 


446       BLADDEE,  PROSTATE,  UEETHEA,  AND  PENIS. 

The  vesical  filaments  of  the  sympathetic  do  not  stop  at  the 
prostate,  but  pass  on  beneath  the  pubic  arch  into  the  corpus  caver- 
nosum  penis.  Thus  the  erectile  tissue  of  the  intromittent  organ  is 
brought  directly  within  the  influence  of  the  sympathetic  system.* 


STRUCTURE  OF  THE  BLADDER,  PROSTATE,  URETHRA,  AND  PENIS. 

It  is  assumed  that  the  parts  have  been  collectively  taken  out 
of  the  pelvis,  and  that  the  partial  peritoneal  covering  of  the 
bladder  has  been  removed. 

The  bladder,  in  a  fairly  dilated  condition,  measures  about  five 
inches  in  length  and  three  in  breadth. 

STRUCTURE  OF  The  bladder   is    composed    of  a    partial   peri- 

THE  BLADDER.  toneal  coat,  a  muscular,  and  a  mucous ;  between 
the  last  two  there  is  -a  layer  of  connective  tissue,  which  the  old 
anatomists  called  the  cellular  coat. 

The  serous  or  peritoneal  coat  invests  the  posterior,  lateral, 
and  superior  surfaces  of  the  bladder ;  it  is  absent  on  the  anterior 
and  inferior  aspect. 

The  muscular  coat  is  situated  beneath  the  serous,  and  consists 
of  unstriped  or  involuntary  muscular  fibres,  which  interlace  with 
each  other  in  all  directions.  Their  general  arrangement  is  as 
follows : — An  outer,  or  longitudinal,  layer  arises  from  the  upper 
half  of  the  circumference  of  the  prostate  and  the  neck  of  the 
bladder,  and  thence  its  fibres  spread  out  longitudinally  over  the 
summit  of  the  bladder,  pass  round  its  posterior  aspect  and  base,  to 
be  inserted  into  the  prostate  in  the  male,  and  the  vagina  in  the 
female.  This  layer  is  especially  marked  on  the  anterior  and 
posterior  surfaces  of  the  bladder.  Under  this  is  a  thin  layer  of 
circular  fibres,  especially  developed  near  the  neck,  where  they 
form  a  sphincter — sphincter  vesicce.  Towards  the  sides  of  the 
bladder  the  two  sets  of  fibres  have  a  less  definite  arrangement, 
and  form  a  kind  of  network :  these,  therefore,  are  the  weakest 

*  Miitler. 


BLADDER,  PROSTATE,  URETHRA,  AND  PENIS. 
FIG.  101. 


447 


Prostate  gland 


Membranous  part  ot 
the  urethra  .    .    . 


Ureter. 


Orifice  of  ureter. 


Uvula. 

-  Caput  gallinaginis. 
Orifice  •  of    seminal 
duct. 

Cowper's  gland. 
Bulb  of  urethra. 
Crus  penis. 

Orifice  of  the  duct  of 
Cowper's  gland. 


One  of  the  lacuna. 

Corpus  cavernosnm 
penis. 


_    G  lans  penis, 


BLADDER    AND    UHETHBA,    LAID   OPEN   BY    AN    INCISION    ALONG   THE    UPPER   SURFACE. 


448       BLADDER,  PROSTATE,  UEETHRA,  AND  PENIS. 

parts  of  the  bladder,  and  more  liable  to  the  formation  of  pouches.* 
The  development  and  colour  of  the  muscular  fibres  depend  upon 
how  far  the  subject  has  suffered  from  irritation  of  the  bladder, 
or  any  obstruction  to  the  expulsion  of  the  urine. 

The  mucous  coat  is  everywhere  loosely  connected  to  the 
muscular,  except  at  the  trigone  of  the  bladder,  where  they  adhere 
more  firmly. 

The  bladder  must  be  laid  open  by  an  incision  along  its  front, 
to  examine  its  interior.  In  a  recently  contracted  bladder,  the 
mucous  membrane  is  disposed  in  irregular  folds,  which  disappear 
when  the  bladder  is  distended.  In  a  healthy  state,  it  is  pale  ; 
when  inflamed,  it  becomes  of  a  bright  red.  Under  the  microscope, 
its  surface  is  seen  to  be  studded  with  mucous  follicles.  These 
follicles  secrete  the  thick  ropy  mucus  in  inflammation  of  the 
bladder. 

The  vesical  orifice  of  the  urethra  is  situated  at  the  lower  and 
anterior  part  of  the  bladder,  not  at  the  most  dependent  part,  which 
forms  the  pouch  behind  the  orifice,  in  which  urine  is  apt  to  accu- 
mulate in  old  persons.  It  appears  small  and  contracted  in  the  fresh 
bladder,  but  if  the  little  finger  be  introduced  into  it,  it  will  dilate 
considerably.  Immediately  behind  the  orifice  there  is,  in  some 
bladders,  a  slight  elevation,  called  the  uvula.  It  is  composed 
of  a  portion  of  the  mueous  membrane  raised  up  by  an  accumulation 
of  the  submucous  tissue,  but  is  rarely  of  sufficient  size  to  interfere 
with  the  passage  of  the  urine.  This  elevation  must  be  dis- 
tinguished from  enlargement  of  the  third  or  middle  lobe  of  4the 
prostate. 

The  orifices  of  the  ureters  are  situated  about  an  inch  and  a 
half  behind  the  urethra,  and  about  two  inches  apart.  These  tubes 

*  These  pouches  arise  in  the  following  manner  : — A  portion  of  mucous  membrane 
is  protruded  through  one  of  the  muscular  interstices,  so  as  to  form  a  little  sac.  This 
is  small  at  first,  but  gradually  increases  in  size,  because,  having  no  muscular  coat,  it 
has  no  power  of  emptying  itself ;  generally  speaking,  several  such  sacs  are  met  with 
in  the  same  bladder ;  and  they  sometimes  contain  calculi.  If  a  calculus,  originally 
loose  in  the  bladder,  happen  to  become  lodged  in  a  pouch  by  the  side  of  it,  a  sudden 
remission  of  the  symptoms  may  ensue.  This  explains  our  frequent  inability  to  detect 
its  presence  at  each  examination  with  the  sound. 


TEIGONE    OP    THE    BLADDER.  449 

perforate  the  coats  of  the  bladder  obliquely,  and  slant  towards 
each  other,  standing  out  in  relief  under  the  mucous  membrane.* 
A  slight  ridge  proceeds  from  the  orifice  of  each  ureter  to  the  neck 
of  the  bladder,  looking  like  a  continuation  of  the  ureter  itself. 
If  the  mucous  membrane  be  removed  from  these  ridges,  we  find 
that  they  are  produced  by  muscular  fibres.  Sir  Charles  Bell,f 
who  first  drew  attention  to  them,  believed  them  to  be  of  use  in 
regulating  the  orifices  of  the  ureters,  and  named  them  the  muscles 
of  the  ureters. 

TEIGONE  OF  THE  The  ridges,  converging  from  the  ureters,  form 

BLADDER.  with  a  horizontal  line,  drawn  between  their  orifices, 

a  smooth  triangular  area,  called^  by  a  French  anatomist,!  the  trigone 
vesicate.  The  mucous  membrane  of  this  area  is  more  firmly 
adherent  to  the  subjacent  tissue  than  in  other  parts  of  the  bladder, 
and  is  therefore  perfectly  smooth.  It  is  more  richly  provided 
with  blood-vessels  and  nerves  than  the  rest  of  the  bladder,  and  is 
endowed  with  more  acute  sensibility.  This  is  why  a  stone  is  more 
painful  when  the  bladder  is  empty ;  and  in  the  erect,  than  in  the 
recumbent  position. 

The  bladder  is  supplied  with  blood  by  the  superior,  middle, 
and  inferior  vesical  arteries.  The  superior  comes  from  the  un- 
obliterated  portion  of  the  umbilical ;  the  middle,  from  the  superior 
vesical  or  the  internal  iliac ;  the  inferior,  from  the  anterior  division 
of  the  internal  iliac  or  the  pudic. 

The  veins  of  the  bladder  form  large  plexuses  around  its  neck, 
sides,  and  base,  and  empty  themselves  into  the  internal  iliac  veins. 
The  lymphatics  follow  the  course  of  the  veins. 

*  This  slanting  of  the  ureters  serves  all  the  uses  of  a  valve.  The  urine  enters 
the  bladder,  drop  by  drop,  but  cannot  return,  because  the  internal  coat  is  pressed 
against  the  other  side  of  the  orifice,  so  as  to  stop  it.  When  the  bladder  becomes 
thickened,  in  consequence  of  difficulty  in  passing  the  water,  it  sometimes  happens 
that  the  ureters  lose  their  valvular  direction,  so  that  the  urine,  when  the  bladder 
contracts,  is  partly  forced  back  up  the  ureters  ;  the  result  is,  that  they  become  di- 
lated, and  the  pelvis  of  the  kidney  also. 

f  '  Med.  Chir.  Trans."  vol.  iii.     He  says,  '  These  muscles  guard  the  orifices  of  the 
ureters  by  preserving  the  obliquity  of  the  passage,  and  pulling  down  the  extremities  of 
the  ureters  according  to  the  degree  of  the  contraction  of  the  bladder  generally.' 
Lieutaud. 


450  PROSTATE    GLAND. 

Its  nerves  are  derived  from  the  hypogastric  and  sacral  plexuses  ; 
the  former  is  chiefly  distributed  to  the  top,  the  latter  to  the  neck 
and  the  bottom  of  the  bladder. 

Having  already  examined  the  form,  size,  and 
PKOSTA.TB 

relations  of  the  prostate  (p.  438),  we  have  now 

to  make  out  its  lobes.  There  are  two  lateral  lobes,  and  a  third 
or  middle  lobe.*  The  middle  one  is  pyriform  in  shape,  unites  the 
lateral  lobes,  and  is  situated  between  them  and  the  urethra.  In 
health,  it  does  not  appear  like  a  separate  lobe  ;  but  when  abnor- 
mally enlarged,  it  projects  toward  the  cavity  of  the  bladder,  and 
acts  like  a  bar  at  the  mouth  of  the  urethra. 

Make  a  longitudinal  incision  through  the  upper  surface  of  the 
prostate  to  expose  the  urethra.  This  canal  runs  rather  nearer  to 
its  upper  than  its  lower  surface,  and  is  not  of  the  same  calibre 
throughout.f  It  forms  a  sinus  in  the  interior  of  the  prostate, 
described  by  anatomists  as  the  sinus  of  the  prostate.  Along  the 
floor  of  the  sinus  is  a  longitudinal  ridge,  about  three-quarters  of 
an  inch  in  length,  broad  and  elevated  behind,  but  gradually 
fading  in  front.  This  is  called  the  crest  of  the  urethra,  and  the 
most  prominent  part  of  it  is  named  the  veru  montanum,  or  caput 
gallinaginis,  from  its  supposed  resemblance  to  the  head  of  a  wood- 
cock. On  each  side  of  this  prominence  the  seminal  ducts  open, 
(p.  447). 

Immediately  in  front  of  the  caput  gallinaginis,  in  the  middle 
line,  is  a  small  opening  which  will  admit  a  probe.  It  leads  back- 
wards into  a  little  cul-de-sac  or  pouch  in  the  substance  of  the 
prostate.  This  pouch  is  described  as  the  analogue  of  the  uterus, 
and  called  the  utriculus  or  sinus  pocularis.  It  is  of  a  pyriform 

*  Attention  was  first  attracted  to  this  middle  lobe,  in  England,  by  Sir  Everard 
Home,  whose  account  of  it  is  published  in  the  'Philos.  Trans.'  for  1806.  The  pre- 
paration prepared  by  Sir  Everard  in  illustration  is  preserved  in  the  Museum  of  the 
Royal  College  of  Surgeons  in  London,  Physiol.  Series,  No.  2583  A.  But  the  anatomy 
and  effect  of  the  enlargement  of  this  part  of  the  prostate  gland  is  not  a  discovery  of 
modern  times.  It  was  accurately  described  by  Santorini  in  1739,  and  subsequently 
by  Camper,  and  is  alluded  to  by  Morgagni  in  the  third  book  of  his  Epistles. 

t  This  part  of  the  urethra  is  about  an  inch  and  a  quarter  long,  and  about  four 
lines  in  diameter. 


PROSTATE    GLAND.  45  I 

shape,  running  backwards  and  upwards,  with  the  narrowest  part  at 
the  orifice,  and  its  length  is  about  five  or  six  lines.  It  ascends 
between  the  lateral  lobes  of  the  prostate,  and  beneath  the  middle  ; 
its  coats  are  comparatively  thick  with  some  muscular  tissue 
enclosed  in  them,  and  it  is  lined  with  squamous  epithelium. 
Practically  it  deserves  attention,  because  in  some  persons  it  is 
large  enough  to  catch  the  end  of  a  small  catheter.  The  minute 
orifices  of  the  proper  ducts  of  the  prostate,  from  fifteen  to  twenty 
in  number,  are  seen  opening  into  the  floor  of  the  prostatic  sinus.* 
The  substance  of  the  gland  is  permeated  by  the  divisions  and  sub- 
divisions of  the  ducts.  They  are  not  visible  to  the  naked  eye,  but 
if  traced  out  with  the  microscope,  they  are  seen  to  terminate  in 
blind  sacculated  extremities,  upon  which  the  capillaries  ramify  in 
rich  profusion.f 

The  prostate  is  composed  of  muscular  as  well  as  glandular 
tissue.  Nearly  two-thirds  of  it  is  made  up  of  plain  muscular 
fibres,  arranged  in  a  circular  manner  round  the  urethra,  at  its 
vesical  orifice,  so  as  to  form  in  conjunction  with  the  vesical 
muscular  tissue,  a  sphincter.  The  anterior  part  of  the  prostate 
is  chiefly  muscular,  its  fibres  being  continuous  with  those  of  the 
membranous  part  of  the  urethra.  The  prostate  is  remarkable  for 
its  dilatability.  If  a  small  incision  be  made  through  the  anterior 
part  of  the  gland,  the  base  being  left  entire,  the  gland  may  be 
dilated  by  the  finger  sufficiently  to  allow  the  extraction  of  even 
large  calculi. 

Any  change  in  the  dimensions  of  the  prostate  affects  the  canal 
which  runs  through  it,  and  more  or  less  obstructs  the  flow  of  urine. 
If  the  entire  gland  be  uniformly  enlarged,  the  length  of  the  pro- 

*  In  the  ducts  of  the  prostate  we  often  find  small  calculi,  of  a  brown  colour,  con- 
sisting of  phosphate  of  lime.  Cases  are  sometimes  met  with  in  which  these  calculi 
by  degrees  attain  a  considerable  size,  and  distend  the  prostate  into  a  sac,  which 
when  examined  by  the  rectum  feels  not  unlike  a  bag  of  marbles. 

f  This  was  first  demonstrated  by  the  late  Mr.  Quekett.  The  same  anatomist 
has  also  discovered  that  the  secreting  cells  of  the  gland  contain  calculi  of  microscopic 
minuteness.  He  finds  them,  almost  without  exception,  in  the  prostate  at  every  period 
of  life.  For  further  detail  concerning  them  consult  the  article  '  Prostate  '  in  Todd's 
'  Cyclopaedia.' 

a  G  2 


452  VESICULJ3    SEMINALES. 

static  urethra  is  increased ;  if  the  enlargement  preponderate  at 
one  part  more  than  another,  then  the  canal  will  deviate  more  or 
less  from  its  natural  track  and  assume  a  more  angular  or  a  lateral 
eurve  according  to  the  part  enlarged.  When  the  middle  lobe 
becomes  enlarged,  there  arises,  at  the  neek  of  the  bladder,  a 
growth  which  will,  in  proportion  to  its  size,  more  or  less  obstruct 
the  passage  of  the  urine.  In  the  efforts  made  to  introduce  a 
catheter  into  the  bladder,  it  sometimes  happens  that  the  end  of 
the  instrument  is  pushed  through  this  hypertrophied  lobe.* 

VESICUL.E  The  external  appearance  of  these  bodies  has 

SEMINALES.  been  already  described  (p.  437).  Respecting  their 

structure,  we  find  that  they  have  an  external  coat  derived  from 
the  recto-vesical  fascia ;  a  middle  or  fibrous,  strong  and  somewhat 
elastic,  and  an  internal  or  mucous.  The  mucous  membrane  is 
lined  by  a  scaly  epithelium,  and  presents  a  honey-combed  structure, 
not  unlike  that  of  the  gall-bladder.  Unstriped  muscular  fibres 
exist  in  the  fibrous  investment  of  the  vesicula3  seminales,  for 
the  purpose  of  expelling  their  contents,  and  are  arranged  partly 
transversely,  on  their  posterior  part,  and  partly  longitudinally,  in 
connection  with  the  vesical  muscular  fibres.  The  duct  emerges 
from  the  anterior  part  of  the  vesicula,  and  joins  at  an  acute  angle 
the  vas  deferens  behind  the  prostate,  to  form  the  common  ejacula- 
tory  duct  (p.  435).  The  function  of  these  bodies  is  twofold:  they 
act  as  reservoirs  for  the  semen,  and  secrete  a  fluid  accessory  to 
generation. 

COWPEE'S  The  glands  of  Cowper  have  been  examined  in 

GLANDS.  8HU  jn  the  dissection  of  the  perineum  (p.  425). 

They  are  placed  close  to  the  urethra,  one  on  either  side,  imme- 
diately behind  the  bulb  and  between  the  two  layers  of  the  trian- 
gular ligament.  They  consist  of  a  number  of  lobules  united 
by  firm  connective  tissue,  and  their  collective  size  is  somewhat 
larger  than  a  pea.  Each  pours  its  secretion  by  a  minute  duct 
about  an  inch  long  into  the  bulbous  part  of  the  urethra.  The 
use  of  these  glands  is  analogous  to  that  of  the  vesiculae  seminales 
and  the  prostate :  namely,  to  pour  into  the  urethra  a  fluid  acces- 

*  See  the  Museum  of  St.  Bartholomew's  Hospital,  Prep.  8  and  21,  Series  xxix. 


URETHRA.  453 

sory  in  some  way  to  generation.  They  are  found  in  all  mam- 
malia, and  in  some — e.g.  the  mole — they  increase  in  size 
periodically  with  the  testicle. 

The  urethra  is  the  canal  which  extends  from 
the  bladder  to  the  end  of  the  penis,  and  serves 
not  only  as  the  outlet  for  the  urine,  but  to  transmit  the  secretion 
of  the  testicles  and  the  several  glands  accessory  to  generation. 
It  is  surrounded  by  different  structures  in  different  parts  of  its 
course.  The  first  inch,  or  thereabouts,  is  surrounded  by  the 
prostate  gland  (p.  433) ;  the  second  inch,  which  passes  under  the 
pubic  arch,  is  surrounded  by  the  compressor  urethra?  (p.  433); 
the  remainder  of  its  course  along  the  penis  is  surrounded  by 
erectile  tissue,  termed  corpus  spongk>sum.  Hence  it  is  divided 
into  the  prostatic,  the  membranous,  and  the  spongy-  parts.  The 
length  of  the  whole  is  about  seven  or  eight  inches,  but  this  varies 
according  to  the  condition  of  the  penis. 

The  direction  of  the  urethra,  when  the  penis  hangs  flaccid,  is 
like  the  letter  S  reversed ;  but  if  the  penis  be  held  straight,  the 
canal  forms  only  one  curve  through  the  pubic  arch,  with  the  con- 
cavity upwards.  The  degree  of  this  curvature  varies  at  different 
periods  of  life.  In  the  child,  the  bladder  being  more  an  abdominal 
than  a  pelvic  viscus,  the  curve  forms  part  of  a  much  smaller 
circle  than  in  the  adult ;  but  it  gradually  widens  as  age  increases, 
and  catheters  are  shaped  accordingly.*  However,  the  parts,  when 
in  a  sound  state,  will  yield  sufficiently  to  admit  the  introduction 
of  a  straight  instrument  into  the  bladder,  A  straight  staff  is 
sometimes  used  in  lithotomy. 

In  its  contracted  state,  the  sides  of  the  urethra  are  in  close 
apposition;  the  appearance  it  presents  on  a  transverse  section 
differs  in  the  different  parts  of  its  course.  Through  the  glans  it 
is  flattened  vertically;  through  the  prostate  it  is  crescentic,  with 
the  convexity  upwards,  owing  to  the  veru  montanum.  But 

*  The  sharper  curve  of  the  urethra  in  the  child  was  well  known  to  Camper.  '  In 
recenter  natis,  vesica  basi  sua  elatius  sita,  pedetentim  descendit,  unde  necessario  se- 
quitur  curvaturam  urethrse  majorem  esse  in  junioribus  quam  in  adultis.' — '  Demon. 
Anat.  Pathol.'  lib.  ii.  p.  13. 


454  UBETHRA. 

throughout  the  rest  of  its  course  the  canal  exhibits  on  section  the 
appearance  of  a  transverse  slit  (fig,  102). 

The  urethra  must  be  laid  open  from  end  to  end,  to  see  that  the 
canal  is  not  of  uniform  calibre  throughout.  The  external  orifice 
is  the  narrowest,  and  the  least  dilatable  part ;  so  that  the  urine 
may  be  expelled  in  a  jet.  Therefore,  any  instrument  which  will 
enter  the  meatus  ought  to  pass  into  the  bladder,  if  there  be  no 
stricture.  The  junction  of  the  membranous  with  the  bulbous  part 
is  almost  as  narrow. 

The  prostatic  and  the  membranous  parts  have  been  de- 
scribed (p.  438). 

The  spongy  part  of  the  urethra,  so  termed  because  it  is  sur- 
rounded by  the  erectile  tissue  of  the  corpus  spongiosum,  is  about 
six  inches  long.  That  part  of  it  running  through  the  bulb  is 

FIG.  102. 


A  Ho 

TBANSVEHSE   SECTIONS    OF    THE    TJKETHRA. 

A.  Through  the  prostate.  B.  Through  the  corpus  spongiosum. 

c.  Through  the  glaus  penis. 

called  the  bulbous  portion,  and  is  the  most  dilatable  part  of  the 
canal  except  the  prostatic.  In  the  centre  of  the  glans  penis  the 
canal  widens  into  a  sinus,  termed  fossa  navicularis. 

The  most  dilatable  part  of  the  urethra  is  the  prostatic.  Even 
the  narrowest  parts  of  the  canal  must  admit  of  considerable  dila- 
tation, since  calculi  of  from  three  to  four  lines  in  diameter  can 
pass  through  it. 

The  common  ejaculatory  ducts  open  into  the  prostatic  part  of 
the  urethra,  by  the  side  of  the  veru  montanum.  The  ducts  of 
Cowper's  glands  open  into  the  bulbous  part.  Besides  these  glands, 
a  number  of  ducts  open  into  the  urethra,  proceeding  from  small 
glands  situated  in  the  submucous  tissue.  These  ducts,  called 
lacunce,  are  large  enough  to  admit  a  bristle,  and  run  in  the  same 


UEETHRA.     PENIS.  455 

direction  as  the  stream  of  the  urine.  Most  of  them  are  on  the 
lower  surface  of  the  urethra  ;  but  one,  called  lacuna  magna,  is  on 
the  upper  surface,  about  one  inch  and  a  half  down  the  canal. 

Beneath  the  mucous  membrane  of  the  urethra  is  a  layer  of 
areolar  tissue,  the  submucous  tissue,  external  to  which  is  a  layer 
of  vascular  tissue  of  variable  thickness ;  outside  this  is  a  layer  of 
unstriped  muscular  fibres.  It  has  been  demonstrated  that  the 
urethra  is  surrounded  throughout  its  whole  course  by  muscular 
fibres  of  the  involuntary  kind.  Therefore,  the  whole  of  the  canal 
having  a  muscular  coat  similar  to  an  intestine,  any  part  of  it  is 
liable  to  spasmodic  contraction. 

The  urethra  is  lined  by  columnar  stratified  epithelium,  except 
near  the  glans,  where  there  are  papillae,  covered  with  squamous 
epithelium ;  this,  therefore,  is  the  most  sensitive  part. 

Lastly,  the  urethra  is  provided  with  a  closely-set  network  of 
lymphatic  vessels,  which  has  been  demonstrated  by  quicksilver 
injections.*  They  run  from  behind,  forwards,  and  join  the  lym- 
phatics of  the  glans  penis.  Eventually,  their  contents  are  trans- 
mitted down  the  great  trunks  on  the  dorsum  penis  to  the  inguinal 
glands.  This  explains  the  pathology  of  a  bubo. 

The  skin  of  the  penis  is  remarkably  thin  and 
extensible,  and  connected  to  the  body  of  the  organ 
by  loose  areolar  tissue,  destitute  of  fat.  At  the  extremity  the 
skin  forms  the  prepuce,  or  foreskin,  for  the  protection  of  the  ' 
glans ;  f  and  the  thin  fold  which  passes  from  the  under  surface  of 
the  glans  to  the  prepuce  is  called  frcenum  preputii.  The  skin, 

*  Panizza,  '  Osservazioni  antropo-zootom.'  &c  ,  Pavia,  1830.  This  anatomist  has 
also  displayed  by  injections  an  extremely  fine  network  of  lymphatics  which  cover 
the  glans  penis.  The  interstices  of  this  network  are  smaller  than  the  diameter  of  the 
tubes. 

f  "When  the  foreskin  is,  from  birth,  so  tight  that  the  glans  cannot  be  uncovered, 
such  a  state  is  called  a  congenital  phimosis.  This  condition  occasions  no  inconveni- 
ence in  childhood,  but  is  apt,  after  puberty,  to  become  troublesome  and  painful,  so 
that  it  may  become  necessary  to  slit  up  the  prepuce  and  set  the  glans  at  liberty.  In 
persons  who  have  a  tight  foreskin,  it  sometimes  happens  that,  when  the  glans  has 
been  uncovered,  the  prepuce  cannot  be  again  drawn  over  it:  this  is  called  a  para- 
phimosis.  The  neck  of  the  glans  becomes  tightly  girt ;  great  distension  and  in- 
flammation are  the  consequences  unless  the  foreskin  be  reduced. 


456  PENIS. 

altered  in  character,  is  reflected  over  the  glans,  to  which  it  is 
intimately  adherent,  and  at  the  orifice  of  the  urethra  is  continuous 
with  the  mucous  membrane. 

The  surface  of  the  glans  is  covered  with  minute  vascular 
papillae,  endowed  with  keen  sensibility  by  the  dorsal  nerves  of 
the  penis.  Round  its  margin — termed  the  corona  glandis — are 
a  number  of  minute  sebaceous  glands,  which  secrete  a  substance 
called  smegma  preputii. 

The  bulk  of  the  penis  consists  of  two  cylindrical  bodies,  of 
erectile  structure,  named  from  the  appearance  of  their  interior 
corpora  cavernosa.  In  a  groove  along  their  under  surface  is 
lodged  a  third  cylindrical  body,  the  corpus  spongiosum,  composed 
of  vascular  spongy  tissue,  through  which  runs  the  urethra  ;  an  ex- 
pansion of  this  at  the  end  of  the  organ  forms  the  glans.  These 
structures,  then — the  corpora  cavernosa  and  the  corpus  spongiosum 
— together  form  the  penis  ;  though  the  corpus  spongiosum  appears 
closely  united  to  the  corpora  cavernosa,  yet  it  is  quite  distinct 
from  them,  as  shown  in  the  transverse  section  (fig.  103). 

The  upper  part  of  the  penis  is  connected  to  the  symphysis 
pubis  by  an  elastic  triangular  ligament,  called  ligamentum  sus- 
pensorium  penis. 

CORPORA  The  corpora   cavernosa  constitute  more  than 

CAVEHNOSA.  two-thirds  of  the  bulk  of  the  penis.     Each  com- 

mences posteriorly  by  a  gradually  tapering  portion,  called  the  cms 
penis,  which  is  attached  along  a  groove  in  the  rami  of  the  ischium 
and  pubes,  where  it  is  embraced  by  the  erector  penis  (p.  420). 
The  two  crura  converge,  come  into  apposition  at  the  root  of  the 
penis,  and  then  run  together  side  by  side  to  form  the  body  of  the 
organ.  Anteriorly,  each  terminates  in  a  rounded  extremity,  received 
into  a  corresponding  depression  in  the  glans,  to  which  it  is  con- 
nected by  fibrous  tissue. 

A  section  through  the  corpus  cavernosum  shows  that  its  inte- 
rior is  composed  of  a  delicate  reticular  structure,  surrounded  by 
a  white  fibrous  and  elastic  coat,  from  half  a  line  to  a  line  in 
thickness. 

The   septum  pectiniforme  is   a    median    vertical    partition 


PENIS.  457 

between  the  two  corpora  cavernosa ;  it  is  only  complete  near  the 
root  of  the  penis  ;  along  the  rest  of  the  organ  there  are  vertical  slits 
in  it,  giving  it  the  appearance  of  a  comb :  hence  its  name.  Through 
the  intervals  in  this  partition  the  blood-vessels  of  the  two  corpora 
cavernosa  communicate  freely  with  each  other. 

From  the  interior  of  the  fibrous  coat  a  number  of  delicate 
septa,  trabeculce,  pass  inwards  into  the  corpus  cavernosum,  inter- 
secting each  other  in  all  directions,  and  forming  a  multitude  of 
small  spaces.  The  trabeculse  consist  of  fibrous  lamellae,  with 
elastic  and  some  non-striated  muscular  tissue.  The  spaces  com- 
municate freely  with  each  other,  as  may  be  readily  ascertained  by 
blowing  air  into  the  penis ;  they  are  smaller  and  their  component 
septa  thicker  at  the  circumference  than  in  the  centre  of  the  corpora 

FIG.  103. 


1.  Corpus  cavernosum.  /^^^prvjf^         *.  «•  ™*°*  Aeries. 

2.  Corpus  spongiosum  urethra.    ±  [j^|>.*^fJ§«/.»/.*;»3]        5,  5.  Dorsal  nerve.. 

3.  Vena  dorsalis. 


TRANSVERSE   SECTION    THROUGH    THE    PENIS. 


cavernosa,  at  the  root  than  towards  the  glans.  Each  corpus 
cavernosum  thus  consists  of  innumerable  spaces  mainly  occupied 
by  dilated  venous  sinuses,  from  which  the  blood  is  conveyed  by 
the  dorsal  vein,  the  prostatic  plexus,  and  the  pudendal  veins. 
When  the  penis  is  flaccid,  these  spaces  are  empty  ;  when  it  is 
erect,  they  are  distended  with  blood. 

The  arteries  of  the  corpora  cavernosa  come  from  the  branches 
of  the  pudic  (p.  427),  which  enter  the  inner  side  of  each  crus, 
and  proceed  forwards  near  the  septum,  distributing  numerous 
ramifications.  These  are  supported  in  the  middle  of  the  fibrous 
septa,  and  end,  some  in  capillaries  which  convey  their  blood 
at  once  into  the  inter-trabecular  spaces,  others  in  tendril-like 
prolongations  with  dilated  extremities  which  project  into  the 


458  PENIS. 

cavities  of  the  veins.  These  arteries,  called  helicine,  are  ab- 
sent near  the  glans,  and  are  best  marked  at  the  root  of  the 
penis. 

The  blood  from  the  inter- trabecular  spaces  of  the  penis  returns 
partly  through  veins  which  pass  out  on  the  upper  surface  of  the 
penis  into  the  dorsal  vein  (which  joins  the  prostatic  plexus), 
partly  through  the  deep  veins  which  leave  the  inner  side  of  each 
crus,  and  the  bulb,  to  join  the  internal  iliac. 

CORPUS  The  corpus  spongiosum  is  the  erectile  tissue 

SPONGIOSUM.  which  surrounds  the  urethra  as  it  runs  along  the 

penis.  It  commences  in  the  middle  of  the  perineum,  anterior  to 
the  triangular  ligament,  in  a  bulb-Aike  form — the  bulb — and  at 
the  end  of  the  penis  it  expands  to  form  the  glans.  It  receives 
posteriorly  an  expansion  from  the  triangular  ligament,  and  pre- 
sents a  median  groove,  marking  its  development  from  two  lateral 
halves.  The  urethra  does  not  pass  through  the  middle  of  the 
spongy  body,  but  runs  nearer  to  its  upper  surface.  The  bulb 
hangs  more  or  less  pendulous  from  the  urethra,  and  is  surrounded 
by  the  accelerator  urinae  muscle  (p.  420).  In  old  persons  it  ex- 
tends lower  down  than  in  children,  and  is,  consequently,  more 
exposed  to  injury  in  lithotomy. 

The  corpus  spongiosum  has  a  much  thinner  external  coat  than 
the  corpus  cavernosum,  but  resembles  it  very  much  in  its  internal 
appearance.  The  reticular  structure,  however,  is  somewhat  finer. 
Its  interior  is  composed  of  a  plexus  of  minute  tortuous  veins. 
This  is  easily  demonstrated  by  injecting  the  dorsal  vein  of  the 
penis  with  wax.  In  this  way  we  not  only  fill  the  spongy  body, 
but  also  the  glans  and  the  large  veins  which  form  the  plexus 
round  the  corona  glandis.* 

The  chief  nerves  of  the  penis  are  the  pudic,  and  its  superficial 
perineal  branch.  The  largest  branches  run  along  the  dorsum  to 
the  surface  of  the  glans :  a  few  only  enter  the  erectile  tissue  of  the 
organ.  This,  it  has  already  been  mentioned  (p.  446),  is  supplied 

*  In  the  Museum  of  the  Royal  College  of  Surgeons  there  is  a  preparation  in  which 
the  glans  penis  is  injected  with  quicksilver,  clearly  showing  it  to  consist  of  a  plexus 
of  reins.— Physiol.  Series,  No.  2588  A. 


DISSECTION   OP   THE   FEMALE   PERINEUM.  450 

by  filaments  of  the  sympathetic  nerve  proceeding  from  the  hypo- 
gastric  plexus.* 

The  lymphatics  proceeding  from  the  glans  and  the  integument 
of  the  penis  join  the  inguinal  glands.  The  lymphatics  of  the 
glans  communicate  freely  all  round  it :  this  explains  why  a 
venereal  sore  on  one  side  sometimes  affects  the  inguinal  glands 
on  the  other.  The  deep  lymphatics  from  the  corpora  cavernosa 
and  the  corpus  spongiosum  join  the  lymphatics  of  the  pelvis. 


DISSECTION  OF  THE  FEMALE  PERINEUM. 

The  pudenda  in  the  female  consist  of  folds  of  the  integument, 
called  the  labia.  Between  these  is  a  longitudinal  fissure  which 
leads  to  the  orifices  of  the  urinary  and  genital  canals. 

The  pubic  region  is  generally  surmounted  by  an 

accumulation  of  fat,  called  mons  Veneris,  which 
is  covered  with  hair.  From  this,  two  thick  folds  of  skin  descend, 
one  on  either  side,  constituting  the  lakia  majora,  and  gradually 
diminish  in  thickness  towards  the  perineum.  Their  junction, 
about  one  inch  above  the  anus,  is  called  the  posterior  commissure, 
or  frcenulum  labiorum:  it  is  generally  torn  in  the  first  labour. 
The  inner  layer  of  the  skin  of  the  labium  is  thinner,  softer,  and 
more  like  mucous  membrane  than  the  outer :  for  this  reason, 
whenever  pus  forms  in  the  labium,  the  abscess  bursts  on  the 
inner  side.  Where  the  labia  are  in  contact,  they  are  provided 
with  small  sebaceous  glands,  of  which  the  minute  ducts  are  observ- 
able on  the  surface. 

In  form  and  structure  the  clitoris  resembles  the 

penis  on  a  diminutive  scale,  being  about  an  inch 
and  a  half  long.  It  has,  however,  no  corpus  spongiosum,  or 
urethra.  Like  the  penis,  it  is  attached  to  the  sides  of  the  pubic 
arch  by  two  crura  (fig.  104,  p.  461),  each  of  which  is  grasped  by 
its  special  erector  clitoridis.  The  crura  are  continued  forward 

*  Krause  has  described  end-bulbs  on  the  nerves,  and  Pacinian  corpuscles  have 
likewise  been  discovered  on  the  nerves  of  the  glans. 


460  DISSECTION    OP    THE    FEMALE    PEEINEUM. 

like  the  corpora  cavernosa  of  the  male,  and  unite  to  form  the  body 
of  the  organ,  which  is  surmounted  by  a  small  glans.  The  glans  is 
provided  with  extremely  sensitive  papillae,  and  covered  by  a  little 
prepuce.  Its  dorsal  arteries  and  nerves  are  large  in  proportion  to 
its  size,  and  have  precisely  the  same  course  and  distribution  as  in 
the  penis.  Its  internal  structure  consists  of  a  plexus  of  blood- 
vessels, which  freely  communicate  with  those  of  the  labia  minora ; 
for  one  cannot  be  injected  without  the  other. 

By  separating  the  external  labia,  two  small  and 

LABIA  MINORA.        ..  .        -  fT    \T^   *  J 

thin  folds  of  integument  are  exposed,  one  on 
either  side,  termed  labia  minora.  These  folds  converge  an- 
teriorly, and  form  a  covering  for  the  clitoris,  called  preputium 
clitoridis ;  posteriorly  they  are  gradually  lost  on  the  inside  of  the 
labia  majora.  They,  unlike  the  labia  majora,  do  not  contain  fat, 
but  are  composed  of  minute  veins.  Between  the  nymphse  and 
about  the  clitoris  are  a  number  of  sebaceous  glands. 

Between  the  labia  minora,  and  below  the  clitoris,  is  an  angular 
depression  called  the  vestibule,  at  the  back  of  which  is  the  meatus 
urinarius.  Immediately  below  this  is  the  vagina,  of  which  the 
orifice  is  partially  closed  in  the  virgin  by  a  thin  fold  of  mucous 
membrane  called  the  hymen. 

A  smooth  channel  called  the  vestibule,  three- 
quarters  of  an  inch  in  length,  leads  from  the 
clitoris  down  to  the  orifice  of  the  urethra.  This  orifice,  meatus 
urinarius,  is  not  a  perpendicular  fissure  like  that  of  the  penis, 
but  rounded  and  puckered,  and  daring  life  has  a  peculiar 
dimple-like  feel,  which  assists  us  in  finding  it  when  we  pass  a 
catheter.  You  should  practise  the  introduction  of  the  catheter  in 
the  dead  subject,  for  the  operation  is  not  so  easy  as  might  at  first 
be  imagined,  provided  the  parts  are  not  exposed.  The  point  of 
the  forefinger  of  the  left  hand  should  be  placed  at  the  entrance  of 
the  vagina,  and  the  meatus  felt  for ;  when  the  catheter,  guided  by 
the  finger,  slips,  after  a  little  manoeuvring,  into  the  urethra.  The 
canal  is  about  one  inch  and  a  half  in  length,  and  runs  along  the 
upper  wall  of  the  vagina  (p.  464).  The  two  canals  are  in  such 
close  apposition  that  you  can  feel  the  urethra  embedded  in  the 


DISSECTION    OP    THE    FEMALE    PERINEUM.  461 

vagina  like  a  thick  cord.  The  urethra  is  slightly  curved  with  the 
concavity  upwards  ;  but  for  all  practical  purposes  it  may  be  con- 
sidered straight.  Its  direction,  however,  is  not  horizontal.  In 
the  unimpregnated  state  it  runs  nearly  in  the  direction  of  the 
axis  of  the  outlet  of  the  pelvis ;  so  that  a  probe  pushed  on  in  the 
course  of  the  urethra  would  strike  against  the  promontory  of  the 
sacrum.  But,  after  impregnation,  when  the  uterus  begins  to  rise 
out  of  the  pelvis,  the  bladder  is  more  or  less  raised  also  in  con- 
sequence of  their  mutual  connection  ;  therefore  the  urethra,  in 
the  latter  months  of  utero-gestation,  acquires  a  much  more  per- 
pendicular course. 

The  female  urethra  is  provided  with  a  compressor  muscle, 
similar,  in  origin  and  arrangement,  to  that  which  surrounds  the 

FIG.  104. 


1.  Meatus  urinarius.  /    &jjf3tfe^&.    \  3-  Bulb  of  vagina. 

2.  Vagina.  /~/M^iiL\    \  4.  Clitoris  with  its  two  crura. 

4 

2/ 

BULB    OF    THE    VAGINA.* 

membranous  part  of  the  urethra  in  the  male.  It  also  passes 
through  the  triangular  ligament  (fig.  105,  p.  464).  The  prostate 
gland  is  wanting,  but  there  are  minute  glands  scattered  around 
the  neck  of  the  bladder.  In  consequence  of  the  wider  span  of  the 
pubic  arch,  and  the  more  yielding  nature  of  the  surrounding 
structures,  the  female  urethra  is  much  more  dilatable  than  the 
male.  By  means  of  a  sponge  tent,  it  may  be  safely  dilated  to 
admit  the  easy  passage  of  the  fore-finger  into  the  bladder.  Ad- 
vantage is  taken  of  this  great  dilatability  in  the  extraction  of 
calculi  from  the  bladder. 

The  mucous  coat  of  the  urethra  is  arranged  in  longitudinal 
folds,  and  is  lined  by  squamous  epithelium,  which  changes  to  the 
spheroidal  variety  near  the  bladder.  Next  to  the  mucous  coat  is 

*  Taken  from  an  injected  preparation  in  the  Musee  Orfila,  at  Paris. 


462  DISSECTION  or  THE  FEMALE  PERINEUM. 

a  layer  of  elastic  and  non  striped  muscular  fibres  intermixed. 
Externally  there  is  a  plexus  of  veins  bearing  a  strong  resemblance 
to  erectile  tissue. 

The  vagina  is  the  canal  which  leads  to  the 
uterus ;  at  present,  only  the  orifice  of  it  can  be 
seen.  It  is  surrounded  by  a  sphincter  muscle,  easily  displayed  by 
removing  the  integument.  The  muscle  is  about  three-fourths  of 
an  inch  broad,  and  connected  with  the  cutaneous  sphincter  of  the 
anus  in  such  a  manner  that  they  together  form  something  like  the 
figure  8. 

On  each  side  of  the  orifice  of  the  vagina,  between  the  mucous 
membrane  and  the  sphincter,  is  a  plexus  of  tortuous  veins,  termed 
the  bulb  of  the  vagina,  from  its  analogy  to  the  bulb  of  the  urethra 
in  the  male.  This  vaginal  bulb  is  about  an  inch  long  and  extends 
across  the  middle  line  between  the  meatus  urinarius  and  the 
clitoris,  as  shown  in  fig.  104. 

The  hymen  is  a  thin  fold  of  mucous  membrane 
which,  in  the  virgin,  extends  across  the  lower 
part  of  the  entrance  of  the  vagina,  about  half  an  inch  behind  the 
fourchette.  In  most  instances  its  form  is  crescent-shaped,  with 
the  concavity  upwards.  There  are  several  varieties  of  hymen: 
sometimes  there  are  two  folds,  one  on  either  side,  so  as  to  make 
the  entrance  of  the  vagina  a  mere  vertical  fissure;*  or  there  may 
be  a  septum  perforated  by  several  openings,  hymen  cmbriformis, 
or  by  one  only,  hymen  circularis.  Again,  there  may  be  no  open- 
ing at  all  in  it,  and  then  it  is  called  hymen  imperforatus.  Under 
this  last  condition  no  inconvenience  arises  till  puberty.  The 
menstrual  discharge  must  then  necessarily  accumulate  in  the 
vagina:  indeed,  the  uterus  itself  may  become  distended  by  it  to 
such  an  extent  as  even  to  simulate  pregnancy.f 

When  the  hymen  is  ruptured,  it  shrivels  into  a  few  irregular 
eminences,  called  carunculce  myrtiformes. 

The  presence  of  the  hymen  is  not  necessarily  a  proof  of  vir- 
ginity, nor  does  its  absence  imply  the  loss  of  it.     Cases  are  re- 

*  Such  a  one  may  be  seen  in  the  Museum  of  the  College,  Phys.  Series,  No.  2843. 
f  See  Burns'  Midwifery. 


PELVIC    VISCERA    IN    THE    FEMALE.  463 

lated  by  writers  on  midwifery  in  which  a  division  of  the  hymen 
was  requisite  to  facilitate  parturition.  In  Meckel's  Museum,  at 
Halle,  are  preserved  the  external  organs  of  a  female  in  whom  the 
hymen  is  perfect  even  after  the  birth  of  a  seven-months'  child. 

BAHTHOLIN'S  Between  the  orifice  of  the  vagina  and  the  erector 

OR  DUVERNEY'S  clitoridis  is  embedded  in  the  loose  tissue  on  either 
GLANDS.  s{^e  a  smail  gland,*  which  corresponds  to  Cow- 

per's  gland  in  the  male.  Each  is  about  half  an  inch  in  length. 
Its  long  slender  duct  runs  forwards  and  opens  on  the  inner  side 
of  the  nympha.  In  cases  of  virulent  gonorrhoea  these  glands 
are  apt  to  become  diseased,  and  give  rise  to  the  formation  of  an 
abscess  in  the  labium,  very  difficult  to  heal. 

The  description  of  the  perineal  branches  of  the  pudic  vessels 
and  nerves,  given  in  the  dissection  of  the  male  perineum,  applies, 
mutatis  mutandis,  to  the  female,  excepting  that  they  are  propor- 
tionably  small,  and  that  the  artery  which  supplies  the  bulb  of  the 
urethra  in  the  male  is  distributed  to  the  bulb  of  the  vagina  in  the 
female. 

DISSECTION   OF  THE  FEMALE  PELVIC  VISCERA. 

The  internal  organs  of  generation — viz.  the  vagina,  uterus,  and 
its  appendages — should  now  be  examined. 

Their  relative  position  should  first  be  noticed ;  and  afterwards, 
their  special  anatomy. 

.,  The  uterus  is  interposed  between  the  bladder  in 

GENERAL  r 

POSITION  OF  THE  front,  and  the  rectum  behind.  From  each  side  of 
UTERUS  AND  ITS  it  a  broad  fold  of  peritoneum  extends  transversely 
APPENDAGES.  ^o  ^e  s^e  of  ^he  peivis>  dividing  that  cavity  into 

an  anterior  and  a  posterior  part.  These  folds  are  called  the  broad 
ligaments  of  the  uterus  (fig.  106,  p.  473).  On  the  posterior  sur- 
face of  the  ligament  are  the  ovaries,  one  on  each  side.  They  are 
completely  covered  by  peritoneum,  and  suspended  to  the  ligament 
by  a  small  peritoneal  fold.  Each  ovary  is  attached  to  the  uterus 
by  a  cord  termed  the  ligament  of  the  ovary.  Along  the  upper 

*  See  Tiedemann,  '  Von  den  Duverneyschen  Driisen  desWeibs.'  Heidelberg,  1840. 


464 


PELVIC    VISCERA    IN    THE    FEMALE. 


part  of  the  broad  ligament  we  find  between  its  layers  a  tube  about 
four  inches  long,  called  the  Fallopian  tube,  which  conveys  the 
ovum  from  the  ovary  into  the  uterus.  For  this  purpose,  one  end 
of  it  terminates  in  the  uterus,  while  that  nearer  to  the  ovary 
expands  into  a  wide  mouth,  furnished  with  prehensile  fringes — 
fimbrice — which,  like  so  many  tentacles,  grasp  the  ovum  as  soon 
as  it  escapes  from  the  ovary.  One  of  these  fimbrise  is  attached  to 
the  ovary.  Lastly,  there  run  up  to  the  ovary,  between  the  layers 

FIG.  105. 


Urethra  surround- 
ed by  its  compres- 
sor muscle .  .  . 


Vagina    .     .     . 


Rectum    .    .    . 


Peritoneum     in 
dotted  outline. 


Uterus. 


VERTICAL    SECTION    THROUGH   THE    FEMALE    PELVIC    VISCEHA. 

of  the  broad  ligament,  the  ovarian  vessels,  which  arise  from  the 
aorta  in  the  lumbar  region,  like  the  spermatic  arteries  in  the  male, 
because  the  ovaries  are  originally  formed  in  the  loins. 

On  the  anterior  surface  of  the  broad  ligament,  on  either  side 
between  its  layers,  is  the  round  ligament  of  the  uterus.  This 
cord  proceeds  from  the  fundus  of  the  uterus,  anterior  to  the 
Fallopian  tube,  through  the  inguinal  canal,  like  the  spermatic 
cord  in  the  male,  and  terminates  in  the  mons  Veneris.  Besides 


PELVIC    VISCERA    IN    THE    FEMALE.  465 

one  or  two  small  blood-vessels,  it  contains  muscular  fibres  analo- 
gous to  those  of  the  uterus :  these  increase  very  much  in  preg- 
nancy, so  that,  about  the  full  term,  the  cord  becomes  nearly  as 
thick  as  the  end  of  the  little  finger.  In  early  life,  the  round  liga- 
ment receives  a  covering  from  the  peritoneum  which  advances  in  a 
tubular  form  into  the  inguinal  canal.  It  corresponds  to  the  pro- 
cessus  vaginalis  of  the  peritoneum  in  the  male.  It  is  called  the 
canal  of  Nuck,  and  is  generally  obliterated  in  the  adult.  It  may 
be  the  seat  of  a  hernia. 

SIDE  VIEW  OF  After  the  removal  of  the  innominate  bone,  as 

THE  FEMALE  described    at  p.  428,   the   vagina,   rectum,   and 

PELVIC  OBGANS.  bladder  should  be  moderately  distended,  and  a 
catheter  passed  into  the  urethra.  This  done,  the  reflections  of  the 
peritoneum  must  be  traced. 

EEFLECTIONS  From  the  front  of  the  rectum  the  peritoneum 

OF  THE  PEBI-  is  reflected  on  to  a  small  part  of  the  posterior  wall 

TONEUM.  of  ^0  vagina,  thus  forming  what  is  called  the 

recto-vaginal  pouch.  From  the  vagina  the  peritoneum  is  con- 
tinued over  the  posterior  surface,  but  only  about  half-way  down 
the  front  of  the  uterus ;  thence  it  is  reflected  over  the  posterior 
surface  of  the  bladder,  on  to  the  wall  of  the  abdomen.  Laterally 
it  is  reflected  from  the  uterus  to  the  sides  of  the  pelvis,  forming 
the  broad  ligaments  (p.  473). 

In  cases  of  ascites  the  fluid  might  distend  the  recto-vaginal 
pouch,  and  bulge  into  the  vagina,  so  that  it  would  be  practicable 
to  draw  it  off  through  this  channel. 

To  the  description  of  the  fascia  already  given  in 
PELVIC  FASCIA.. 

the  dissection  of  the  male  pelvis  (p.  430)  nothing 

need  be  added  except  that  from  the  side  of  the  pelvis  it  is  reflected 
over  the  side  of  the  vagina  and  the  uterus,  as  well  as  the  bladder. 
It  is  this  fascia  which  in  great  measure  supports  the  uterus  in 
its  proper  level  in  the  pelvis.     When,  from  any  cause,  the  fascia 
becomes  relaxed,  there  is  a  liability  to  prolapsus  uteri. 
LEVATOB  ANI.  For  the  description  of  this  muscle  see  p.  439. 

The   female    bladder    is  broader    transversely, 
BLADDEB. 

and,  upon  the  whole,  more  capacious  than  the  male. 

H  H 


466  PELVIC    VISCERA   IN    THE    FEMALE. 

The  vesical  plexus  of  veins  is  not  so  large,  and  there  are  no  vasa 
deferentia  or  prostate  gland.  The  short  urethra  has  a  constrictor 
muscle,  as  in  the  male,  and  is  supported  in  a  similar  manner  by 
the  pelvic  fascia. 

VENOUS  Though  the  veins  round  the  neck  of  the  bladder 

PLEXUS  ABOUT  are  comparatively  small  in  the  female,  attention 
THE  VAGINA.  should  be  directed  to  the  plexus  of  large  veins 

which  surround  the  vagina.  They  communicate  freely  with  the 
veins  about  the  rectum,  and  empty  themselves  into  the  internal 
iliac.  Their  congestion  in  pregnancy  sufficiently  accounts  for  the 
dark  colour  of  the  vagina  and  the  external  organs,  and  the  frequent 
occurrence  of  hsemorrhoidal  tumours.*  These  veins  must  be  re- 
moved, with  the  connective  tissue  in  which  they  are  embedded, 
before  a  clear  view  of  the  parts  can  be  obtained. 

The  urethra  has  already  been  described  (p.  460). 

But,  in  the  side  view  of  the  parts,  we  have  the 
opportunity  of  observing  how  closely  the  bladder  and  urethra  are 
connected  to  the  upper  wall  of  the  vagina ;  and  we  can  understand 
how,  in  cases  of  protracted  delivery,  it  sometimes  happens  that  the 
contiguous  coats  of  the  bladder  and  the  vagina  give  way,  and  that 
a  fistulous  communication  remains  between  them,  through  which 
urine  constantly  dribbles. 

It  is  necessary  to  slit  open  the  whole  of  the 

vagina  along  the  side,  to  obtain  a  clear  idea  of  the 
manner  in  which  it  embraces  the  lower  end  of  the  uterus,  and  of 
the  extent  to  which  the  neck  of  the  uterus  projects  into  it. 

The  length  of  the  vagina,  in  the  unimpregnated  adult,  is,  on 
an  average,  about  4^  inches.  It  may  be  more,  or  less ;  the  dif- 
ference in  each  case  depending  upon  the  depth  of  the  pelvis,  the 
stature  and  age  of  the  individual.  Owing  to  the  curved  direction 
of  the  vagina,  the  anterior  wall  is  about  an  inch  shorter  than  the 
posterior.  The  vagina,  however,  is  never  so  long  that  we  cannot, 

*  During  pregnancy,  varicose  tumours  may  form  even  in  the  vagina.  In  the 
Berlin  '  Med.  Zeitung,'  1840,  No.  11,  a  case  is  related  of  a  woman  who,  at  the  sixth 
month,  bled  to  death  from  the  bursting  of  a  large  vein  in  the  vagina.  Other  cases  of 
the  kind  are  related  by  Siebold. 


PELVIC    VISCEEA    IN    THE    FEMALE.  467 

during  life,  feel  the  neck  of  the  uterus  projecting  at  the  top  of  it ; 
higher  up,  or  lower  down,  according  to  circumstances.  For  in- 
stance, it  is  a  little  lower  down  in  the  erect  than  in  the  recumbent 
position  ;  again,  in  the  early  months  of  utero-gestation,  the  uterus 
descends  a  little  into  the  vagina,  so  that  this  canal  becomes 
shorter :  the  reverse  holds  good  when  the  uterus  begins  to  rise  out 
of  the  pelvis. 

The  axis  of  the  vagina  is  slightly  curved  with  the  concavity 
upwards  ;  it  corresponds  with  the  axis  of  the  outlet  of  the  pelvis. 

The  width  of  the  vagina  is  not  uniform  throughout.  The 
narrowest  part  is  at  the  orifice  ;  it  is  also  a  little  constricted  round 
the  neck  of  the  uterus.  The  widest  part  is  about  the  middle  : 
here  a  transverse  section  through  it  presents  the  appearance  of  a 
broad  horizontal  fissure.  If,  therefore,  you  would  insert  the  bivalve 
speculum  with  the  least  amount  of  pain,  the  blades  of  the  speculum 
should  be  vertical  when  introduced  into  the  orifice,  and  afterwards 
turned  horizontally. 

The  uterus  is  the  hollow  muscular  organ  which 
UTEBUS. 

receives  the  ovum,  retains  it  for  nine  months  to 

bring  it  to  maturity,  and  then  expels  it  by  virtue  of  its  muscular 
walls.  Its  situation  and  peritoneal  connections  have  been  de- 
scribed (p.  463).  Its  axis  slants  forwards,  so  that,  upon  the  whole, 
the  axis  of  the  vagina  and  uterus  describes  a  curve  nearly  parallel 
to  the  axis  of  the  pelvis.  The  uterus,  then,  is  so  placed  that  it  is 
ready  to  rise  out  of  the  pelvis  into  the  abdomen  after  the  embryo 
has  attained  a  certain  size. 

The  uterus  in  the  unimpregnated  state  is  pyriform,  or  rather 
triangular  with  the  angles  rounded,  and  is  somewhat  flattened 
antero-posterioiiy.  Its  average  si/e  is  about  three  inches  long, 
two  inches  broad,  and  one  inch  thick,  at  the  upper  part ;  but  there 
is  variety  in  this  respect,  arising  from  age,  the  effect  of  preg- 
nancies, and  other  causes. 

For  convenience  of  description,  the  uterus  is  divided  into  the 
fundus,  the  body,  and  the  cervix.  The  term  fundus  is  applied  to 
the  broadest  part,  which  lies  above  the  level  of  the  Fallopian 
tubes  (p.  464).  The  body  is  the  central  part,  while  the  cervix  is 

H  H    2 


468  PELVIC    VISCERA   IN   THE    FEMALE. 

the  narrow  part  which  projects  into  the  vagina.  The  vagina  is 
very  closely  attached  round  the  neck  of  the  uterus :  observe  that 
it  is  attached  higher  up  behind  than  in  front.  The  mouth  of  the 
uterus,  os  uteri,  is  at  the  apex  of  the  neck. 

Postponing  for  the  'present  the  examination  of  the  interior 
of  the  vagina  and  uterus,  let  us  pass  on  to  the  vessels  and  nerves 
of  these  organs. 

UTERINE  AND  ^n  addition  to  the  ovarian  arteries  (which  corre- 

VAGINAI,  spond  to  the  spermatic  arteries  in  the  male)  given 

ABTEEIES.  .off  from  the  abdominal  aorta  (p.  385),  each  inter- 

nal iliac  artery  furnishes  a  branch  to  the  uterus  and  another  to  the 
vagina. 

The  uterine  artery  proceeds  from  the  anterior  division  of  the 
internal  iliac,  towards  the  neck  of  the  uterus,  between  the  layers 
of  the  broad  ligament,  and  then  ascends  tortuously  by  the  side  of 
the  uterus,  giving  off  numerous  branches  to  it,  which  anastomose 
freely  with  each  other,  and  with  a  small  branch  from  the  ovarian 
artery.  The  fundus  of  the  uterus  is  mainly  supplied  with 
branches  from  the  ovarian  arteries. 

The  vaginal  artery  ramifies  along-  the  side  of  the  vagina,  and 
distributes  branches  to1  the  lower  part  of  the  bladder  and  the 
rectum. 

The  veins,  corresponding  with  the  arteries,  form  the  uterine  and 
vaginal  plexuses,  which  empty  themselves  into  the  internal  iliac. 
'  NERVES  OF  THE          The  nerves  of  the  uterus  are  derived  from  the 
UTERUS.  third  and  fourth   sacral  nerves,  from  the  hypo- 

gastric  and  ovarian  plexuses  (p.  408).  They  accompany  the  blood- 
vessels in  the  broad  ligament  to  the  neck  of  the  uterus,  and  ascend 
with  them  along  its  sides. 

Some  small  filaments  continue  with  the  vessels,  and  form 
around  them  plexuses,  upon  -which  minute  ganglia  are  found.* 
But  most  of  the  nerves  soon  leave  the  vessels,  and,  subdividing, 
sink  into  the  substance  of  the  -uterus,  chiefly  about  its  neck  and 
the  lower  part  of  its  body.  A  branch  may  be  traced  passing  up 
to  the  fundus  of  the  uterus,  and  another  to  the  Fallopian  tube. 
*  Beck,  'Philosophical  Transactions  '  for  1846. 


PELVIC    VISCERA    IN    THE    FEMALE.  409 

The  nerves  of  the  uterus  enlarge  during,  pregnancy  like  the 
arteries.  Surgically  speaking,  the  os  uteri  may  be  said  to  have  no 
nerves ;  for  it  is  insensible  to  the  cautery  and  to  the  knife. 

The  lymphatics -of  the  uterus  are  small  in  its  unimpregnated 
state,  but  greatly  increase  in  size  when  it  is  gravid.  Those  from 
the  fundus  and  the  ovaries  proceed  with,  the  ovarian  vessels  to  the 
lumbar  glands ;  thus  explaining  the  affection  of-  these  glands  in 
ovarian  disease.  Those  from  the  body. and  the  lower  part  of  the- 
uterus  accompany  the  uterine  arteries,, and  join,  the  glands  in  the 
pelvis  ;  some,  however,  run  with  the  round  ligament  to  the  groin ; 
hence,  in  certain  conditions  of  the  uterus  the  inguinal  glands  may 
be  affected. 

g  The  uterus,  vagina,  ovaries,  and  Fallopian  tubes 

THE  VAGINA,  should  now  be  collectively  removed  from  the  pelvis 

UTERUS,  OVARIES,     for  the  purpose  of  examining  their  internal  struc- 
AND  FALLOPIAN          ture 

The  vagina  having  already  been  laid  open, 
(p.  466),  we  observe  that,  it  is  lined  by  a  mucous  membrane  of  a 
pale  rose  colour;  and 'that  it  is  rougtu-and  <  furrowed,  especially 
near  the  orifice.  Two  ridges,  columnce  ruganum,  run  one ,  along 
its  anterior,  another  along  its  posterior  wall.  From  either  side  of 
these  proceed  a  series  of  transverse  ridges — rugce — with  rough, 
jagged  margins  directed  forwards.  They  are  well  marked  in 
virgins,  but  repeated  parturition  and  increasing  age  gradually 
smooth  them  down.  The  .use  of  the  vaginal  rugae  is  to  excite  the 
sensibility  of  the  glans  in .  coition.  They  themselves  also  possess 
keen  sensibility,  being  richly  endowed  with  papillae. 

The  mucous  membrane  is  provided  with  numerous  papilla?, 
conical  and  filiform,  and  covered  with  a  thick  lining  of  squamous 
epithelium..  In  the  submucous  tissue  is  an  abundant  supply  of 
muciparous  glands,  which  increase  in  number  and  size  towards 
the  uterus. 

The  chief  strength  of  the  vagina  depends  upon,  a  fibre-cellular 
coat,  about  one-twelfth  of  an  inch  in  thickness.  If  this  coat  be 
minutely  injected,  we  find  that  it  is.  composed 'mainly  of  the  inos- 
culations of  blood-vessels,  so  much  so  that  by  some  it  is  regarded 


470  PELVIC   VISCERA    IN    THE    FEMALE. 

as  erectile  tissue.  In  this  coat,  muscular  fibres,  longitudinal  and 
circular,  have  been  demonstrated.  The  orifice  of  the  vagina  is 
surrounded  by  a  circular  muscle,  called  sphincter  vagince  (p.  462). 
Superiorly,  the  vagina  is  intimately  attached  to  the  neck  of  the 
bladder,  while  to  the  rectum  it  is  but  loosely  connected. 

Before  the    uterus  is  laid    open,   examine   the 
UTERUS 

shape  of  that  portion  of  the  neck  which  projects 

into  the  vagina.  The  back  part  of  the  cervix  appears  to  project 
into  the  vagina  more  than  the  front ;  but  this  arises  from  the 
vagina  being  attached  higher  up  posteriorly.  If  the  vagina  were 
cut  away  from  the  cervix,  the  anterior  lip  of  the  uterus  would 
appear  to  project  a  trifle  more  than  the  posterior.  For  this 
reason,  as  well  as  on  account  of  the  natural  slope  forwards  of  the 
uterus,  the  front  lip  is  felt  first  in  an  examination  per  vaginam.* 
The  length,  however,  and  the  general  appearance  of  the  vaginal 
part  of  the  cervix  vary  according  to  the  age ;  it  is  also  consider- 
ably altered  by  parturition.  In  the  adult  virgin  it  is  smooth  and 
round,  and  projects  about  half  an  inch  :  its  mouth  is  a  small 
transverse  fissure.  But  after  parturition,  it  loses  its  plumpness, 
the  lips  become  flaccid  and  fissured,  and  the  mouth  larger  than  it 
was  before,  f 

The  uterus  must  now  be  laid  open  by  a  longitudinal  incision, 
to  examine  its  interior.  In  doing  so,  observe  the  thickness  of  its 
walls,  which  is  greatest  towards  the  fundus.  Before  coming  into 
the  proper  cavity  in  the  body  of  the  uterus,  slit  up  a  long  narrow 
canal  which  leads  up  into  it  through  the  neck.  This  canal,  which 

*  This  is  the  only  way  to  reconcile  the  discrepancies  one  meets  with  in  anatomical 
works,  respecting  the  comparative  length  of  the  lips  of  the  uterus.  Krause,  Weber, 
Busch,  and  others,  say  the  anterior  is  the  longer ;  Mayer,  Meckel,  Quain,  and  others, 
the  posterior. 

f  Instances  are  recorded  in  which  the  neck  of  the  uterus  is  preternaturally  long. 
It  has  been  known  to  project  even  as  much  as  an  inch  and  a  half  into  the  vagina.  In 
such  cases  it  gradually  tapers,  and  terminates  in  a  very  narrow  mouth.  This  is  said 
to  be  one  cause  of  sterility,  and  it  is  recommended  either  to  dilate  the  mouth,  or  to 
cut  off  a  portion  of  the  neck.  In  support  of  this  opinion,  it  is  stated  that  Dupuytren 
was  once  consulted  by  a  lady  on  account  of  barrenness ;  finding  the  neck  of  the  uterus 
unusually  elongated,  he- removed  a  portion  of  it;  and  shortly  the  lady  became  preg- 
nant. (Hyrtl,  '  Handbuch-der  ^op.  Anatoiri.') 


PELVIC    VISCEEA    IN   THE    FEMALE.  471 

is  about  an  inch  in  length,  is  not  of  the  same  dimensions  through- 
out :  it  is  dilated  in  the  middle,  and  gradually  narrows  towards 
each  end.  The  upper  end,  which  leads  into  the  body  of  the 
uterus,  is  called  os  internum;  the  lower  end,  which  leads  into  the 
vagina,  os  externum.  The  passage  is  called  the  canal  of  the  cer- 
vix. It  remains  unchanged  in  pregnancy  for  some  time  after  the 
cavity  in  the  body  has  expanded,  but  gradually  disappears  with 
the  increasing  size  of  the  embryo. 

The  shape  of  the  cavity  in  the  body  of  the  uterus  is  triangular, 
with  the  apex  towards  the  cervix.  In  a  virgin  uterus  the  cavity 
is  very  small,  and  its  sides  are  convex  ;  but  in  a  uterus  which  has 
borne  many  children,  the  cavity  has  lost  the  convexity  of  its  sides, 
and  has  increased  in  capacity.  Each  angle  at  the  base  is  some- 
what prolonged,  and  leads  to  the  minute  opening  of  the  Fallopian 
tube.  This  prolongation  of  the  angles  is  noticed  more  or  less  in 
different  females,  and  is  the  last  indication  of  the  two  horns  of  the 
uterus  in  some  orders  of  mammalia. 

The  interior  of  the  uterus  is  smooth  at  the  fundus;  but  the 
reverse  at  the  cervix.  Here  there  is  a  central  longitudinal  ridge, 
both  in  front  and  behind  (as  in  the  vagina);  from  these,  other 
closely  set  oblique  ridges  curve  off  laterally,  like  the  branches  of  a 
palm-tree.  In  olden  time  it  was  called  '  arbor  vitce."1  The  rough- 
ness produced  by  these  ridges  occasions  an  impression  as  though  we 
were  touching  cartilage  when  a  sound  is  introduced  into  the  uterus. 

The  neck  of  the  uterus  is  provided  with  small  muciparous 
glands,  of  which  the  minute  ducts  open  in  the  furrows  between 
the  ridges  referred  to.  The  secretion  of  these  glands  is  glairy, 
albuminous,  and  slightly  alkaline.  Soon  after  impregnation,  the 
secretion  becomes  so  firm  as  to  plug  the  mouth  of  the  uterus,  but 
shortly  before  and  during  parturition  it  is  poured  out  in  great 
quantity,  to  facilitate  the  passage  of  the  child.  It  happens  oc- 
casionally that  one  or  more  of  the  ducts  of  these  glands  become 
obstructed,  and  then  dilate  into  small  transparent  vesicles,  which 
gradually  rise  to  the  surface  and  burst.* 

*  These  were  first  described  by  Naboth,  and  supposed  to  be  true  ova :  hence  their 
name  ovula  Nabothi.     '  De  sterilitate  mulierum.'     Lips.,  1707. 


472  PELVIC    VISCERA   IN   THE    FEMALE. 

The  mucous  membrane  of  the  uterus  is  more  delicate  and 
softer  than  that  of  the  vagina,  with  which  it  is  continuous, 
and  is  closely  united  to  the  subjacent  tissue.  The  greater  part  of 
it  is  lined  by  a  columnar  ciliated  epithelium,  but  that  which  lines 
the  lower  part  of  the  cervix  is  squamous,  like  that  of  the  vagina. 
Examined  with  a  lens,  the  mucous  membrane  lining  the  body  of 
the  uterus  is  seen  to  be  covered  with  minute  follicles  or  tubes 
(uterine  glands)  arranged  at  right  angles  to  its  surface.  These 
tubes  pass  outwards  in  a  more  or  less  spiral  manner,  some 
of  them  appearing  branched  and  dilated  at  their  extremities. 
They  become  greatly  developed  shortly  after  impregnation,  and 
take  an  important  part  in  the  formation  of  the  membrana 
decidua. 

The  greater  part  of  the  walls  of  the  uterus  consists  of  non- 
striped  or  involuntary  muscular  fibres,  which  are  chiefly  aggre- 
gated at  the  fundus,  less  so  at  the  junction  of  the  Fallopian  tubes. 
The  texture  of  these  fibres  is  so  close  and  so  interwoven  that  in 
the  unimpregnated  uterus  it  is  useless  to  attempt  to  trace  them. 
The  fibres  are  arranged  in  three  layers,  an  external,  a  middle, 
and  an  internal.  The  external  layer,  placed  immediately  beneath 
the  peritoneum,  is  thin,  and  its  fibres  run  transversely  round  the 
uterus,  some  of  them  being  continued  in  an  oblique  direction  into 
the  round  and  broad  ligaments.  A  band  of  longitudinal  fibres 
passes  from  the  anterior  surface  of  the  uterus  round  the  fundus  to 
its  posterior  aspect.  The  middle  layer  runs  in  all  directions,  and 
chiefly  surrounds  the  blood-vessels.  The  internal  and  thickest 
layer  is  composed  mainly  of  concentric  circles  which  surround  the 
orifices  of  the  Fallopian  tubes;  at  the  cervix  its  fibres  are  ar- 
ranged transversely,  forming  a  sphincter.  Upon  the  whole  their 
collective  disposition  is  such  as  to  exert  equal  pressure  on  all 
sides,  when  called  into  operation. 

At  the  same  time  that  they  expel  the  fcetus,  the  muscular 
fibres  perform  another  very  important  function:  they  close  the 
large  venous  sinuses  consequent  upon  the  great  increase  in  the 
amount  of  blood  during  pregnancy.  Therefore,  little  haemorrhage 
accompanies  the  expulsion  of  the  placenta,  provided  it  have  been 


PELVIC    VISCERA    IN    THE    FEMALE. 


473 


attached  to  the  fundus  or  the  side  of  the  uterus.  But  everyone 
knows  the  danger  of  what  is  called  placenta  prcevia.  Here,  the 
placenta,  placed  entirely  or  partly  over  the  orifice  of  the  uterus, 
is  attached  to  a  part  of  the  organ  which  must  of  necessity  expand 
during  labour;  and  every  uterine  contraction  increases,  instead  of 
checking,  the  bleeding.  For  the  same  reason,  paralysis  of  the 
muscular  fibres  in  immediate  connection  with  the  placenta,  be  it 
where  it  may,  is  likely  to  be  a  source  of  serious  haemorrhage  in 
parturition. 

FALLOPIAN  The  Fallopian  tubes  or  oviducts  are  situated, 

TUBES,  one  on  each  side,  along  the  upper  border  of  the 

Fra.  .106, 


DIAOBAM    OF    THE    UTEBTIS,    ITS    BEOAD    LIGAMENTS,    THE    OVAHIES  AND  FALLOPIAN  TUBES. 
SEEN  •  FfiOM  .  BEHIND. 


1.  Uterus. 

2.  Ovary,  with  its  ligaments. 

3.  Fallopian  tube. 


4.  Fimbriated  extremity  of  Fallopian  tube. 

5.  5.  Broad  ligament. 

6.  Vagina. 


broad  ligament  of  the  uterus,  and  convey  the  ovum  from  the 
ovary  to  the  uterus  (fig.  106).  They  are  about  three  or  four  inches 
in  length.  One  end  opens  into  the  uterus ;  the  other  terminates  in 
a  wide  funnel-shaped  mouth,  surrounded  by  fringe-like  processes 
called  the  fimbriated  extremity.  This  termination  of  the  Fal- 
lopian tube  extends  about  an  inch  beyond  the  ovary ;  and,  by  float- 
ing it  in  water,  one  or  two  of  the  fimbriaB  may  be  seen  connected 
with  the  outer  end  of  the  ovary.  If  the  Fallopian  tube  be  opened 
from  the  expanded  end,  and  a  probe  introduced  into  it,  you  will 


474  PELVIC    VISCERA    IN    THE    FEMALE. 

find  that  the  tube  runs  very  tortuously  at  first,  then  straight  into 
the  uterus,  gradually  contracting  in  size,  so  that  the  uterine  orifice 
scarcely  admits  a  bristle.  Its  mucous  lining  is  gathered  into 
longitudinal  wavy  folds,  especially  at  the  ovarian  end,  and  is  pro- 
vided with  a  columnar  ciliated  epithelium.  The  free  end  of  the 
tube  communicates  with  the  cavity  of  the  peritoneum.  This  is 
the  only  instance  where  a  mucous  membrane  is  directly  con- 
tinuous with  a  serous  one.  It  explains  how  the  embryo  may 
escape  into  the  peritoneal  cavity  ;  though  this  is  an  extremely 
rare  occurrence.  It  also  explains  what  is  said  to  have  occurred  : 
namely,  the  escape  of  the  fluid  in  dropsy  through  the  Fallopian 
tubes.  In  a  well-injected  subject,  the  Fallopian  tubes  are  seen  to 
be  well  supplied  with  blood  from  the  ovarian  arteries.  They  are 
provided  with  non-striped  muscular  fibres :  the  outer  layer  being 
arranged  longitudinally;  the  inner,  in  circles. 

The  ovaries  (called  by  Galen,  testes  muliebres) 
are  situated  at  the  back  of  the  broad  ligament  of 
the  uterus,  between  its  two  layers,  but  more  or  less  suspended 
by  a  short  fold  of  peritoneum.  Besides  this,  they  are  con- 
nected on  their  inner  side  to  the  uterus  by  a  thin  cord,  called  the 
ligament  of  the  ovary.  They  are  oblong,  with  the  long  axis 
transverse,  and  a  little  smaller  than  the  testicles.  In  females 
who  have  not  often  menstruated,  their  surface  is  smooth  and 
even ;  in  after-life,  they  become  puckered  and  scarred  by  the 
repeated  escape  of  the  ova. 

The  ovary  is  about  an  inch  and  a  half  long,  and  weighs  about 
a  drachm  and  a  half.  It  has  nearly  the  same  coverings  as  the 
testicle :  viz.  a  serous  coat,  which  is  covered  with  columnar 
epithelium,  and  beneath  it  a  proper  fibrous  coat,  the  tunica  albu- 
ginea.  If  a  section  be  made  through  the  ovary,  you  find  that 
it  contains  transparent  vesicles,  embedded  in  a  soft  fibro-nuclear 
tissue,  remarkably  vascular  when  well  injected,  called  the  stroma 
of  the  ovary.  The  outer  part  of  the  ovary  is  chiefly  occupied  by 
these  vesicles ;  the  central  part,  in  which  there  are  very  few,  is 
composed  almost  entirely  of  the  stroma. 

The  transparent  vesicles  just  alluded  to  are  the  ovisacs  or 


STRUCTURE    OF   THE    LIVER.  475 

Graafian  vesicles.*  They  vary  in  number  from  eight  to  thirty, 
and  in  size  from  that  of  a  pin's  head  to  a  pea.f  The  smallest  are 
near  the  centre;  but  as  they  advance  towards  maturity,  they 
gradually  approach  the  surface,  increasing  at  the  same  time  in 
size.  Their  proper  tunic  is  very  vascular  and  lined  by  several  layers 
of  granular  prismatic  epithelium  cells,  called  the  tunica  granulosa, 
and  they  contain  a  transparent  albuminous  fluid.  On  examining 
the  contents  of  one  of  the  larger  vesicles  under  the  microscope, 
you  find  in  it  the  ovum  or  germ,|  surrounded  by  a  layer  of 
granular  cells  called  the  discus  proligerus.  It  is  this  ovum  which, 
escaping  from  the  Graafian  vesicle  on  the  surface  of  the  ovary, 
is  grasped  by  the  fimbriated  end  of  the  Fallopian  tube  and  con- 
veyed into  the  uterus.  The  ruptured  vesicle  is  converted  soon 
afterwards  into  a  yellowish-looking  mass  called  corpus  luteum, 
which  persists  for  a  while,  and  degenerates  afterwards  into  a  small 
stellate  fibrous  cicatrix. 

The  ramifications  of  the  ovarian  artery  through  the  ovary  are 
remarkable  for  their  convolutions :  they  run  in  parallel  lines,  as  in 
the  testicle.  Its  nerves  are  derived  from  the  ovarian  plexus.  The 
ovarian  veins  form,  like  the  spermatic  veins,  near  the  ovary  the 
pampiniform  plexus,  and  then  terminate,  the  right  in  the  inferior 
vena  cava,  the  left  in  the  renal. 


DISSECTION   OF   THE    ABDOMINAL    VISCERA. 

The  liver  is  the  largest  gland  in  the  body,  and 
THE  LIVER.  .  .         &         &  •    , 

in  the  adult  weighs  trom  nity  to  sixty  ounces. 

Its  surface  is  entirely  covered  by  peritoneum,  except  a  small  part 
behind,  which  is  connected  to  the  diaphragm  and  the  upper  part 
of  the  right  kidney  by  cellular  tissue,  and,  again,  in  the  hollow  for 

*  So  called  after  De  Graaf,  a  Dutch  anatomist,  who  discovered  them  in  1672,  and 
believed  they  were  the  true  ova. 

f  From  the  y^tti  to  the  ^th  of  an  inch  in  diameter. 

J  This  was  first  distinctly  pointed  out  by  Von  Baer  in  1827. 


476  STRUCTURE    OF    THE    LIVER. 

the  gall-bladder.  Behind,  the  liver,  is  thick  and,  round,  but 
towards  the  front  it  gradually  slopes  to  a  sharp,  border..  The 
upper  surface  is  smooth  and -convex,  in  adaptation  to  the  dia- 
phragm, and  is  marked  by  a  white  line  which  indicates  its  divi- 
sion into  a  right  and  left  lobe,  the  right  being  the  larger.  The 
under  surface  is  irregular  and  marked  by  five  fissures  which  map 
out  the  five  lobes  (fig.  107) : — 1.  The  lonqitu- 

FlSSUEES  . 

dinal  fissure,  dividing  the  right  from  the  left 
lobe,  contains  the  round  ligament  (the  remains -of  the  umbilical 
vein).  2.  The  continuation  of  the  longitudinal  fissure  to  the  pos- 
terior border  of  the  liver,  contains  the  remains  of  what  was,  in 
the  foetus,  .the  ductus  venosusr  and  is  therefore  called  the  fissure, 
for  the  ductus  venosus.  3..  The  KolLow  or  fissure  for  the  gall- 
bladder. In  the  same  line  with  this  is,  4,  the  fissure  for  the 
inferior  vena  cava,  which  passes  obliquely  inwards  towards  the 
posterior  border  of  the  liver.  5.  The  transverse  or  portal  fissure 
unites  the  other  fissures,  and  transmits  the  great  vessels  which 
enter  the  liver  in  the  following  _  order  :  in  front  is  the  hepatic 
duct,  behind  is  the  vena  portay  and  between  them  the  hepatic 
artery.  The  relative  position  of  these  fissures  (the  liver  being  in 
situ)  may  be  best  impressed  on. the  memory  by  comparing  them 
collectively  to  the  letter  H.  The  transverse  fissure  represents  the 
cross-bar  of  the  letter;  the  longitudinal  fissure  and  the  fissure  of 
the  ductus  venosus  represent  the  left  bar ;  the  fissures  of  the  gall- 
bladder and  vena  cava  make  the  right  bar. 

The  lobes  of  the  liver,  five  in  number,  are  also 

seen  on  its  under  surface.  The  right  lobe,  much 
larger  than  the  left,  is  separated  from  it  by  the  longitudinal  fissure. 
On  the  under  surface  of  the  right  lobe  are  two  shallow  fossce ;  the 
anterior  is  for  the  hepatic  flexure,  of  the  colon,  the  posterior  for 
the  right  kidney.  The  remaining  lobes  may  be  considered  as 
forming  parts  of  the  right  lobe,  and  are  the  lobulus  Spigelii, 
the  lobulus  caudatus,  and  the  lobulus  quadratus.  The  lobulus 
Spigelii  is  placed  between  the  fissures  for  the  ductus  venosus,  and 
the  vena  cava,  and  the  transverse  fissure ;  and,,  behind  the  trans- 
verse fissure,  it  is  connected  to  the  right  lobe  by  a  ridge — the 


STRUCTUBE    OP    THE    LIVER. 


477 


lobulus  caudatus.  The  lobulus  quadratus  is  situated  between 
the  gall-bladder,  the  longitudinal,  and  the  transverse  fissure.  This 
lobe  is  occasionally  connected  with  the  left  lobe  by  a  bridge  of 
hepatic  substance  (ports  hepatis)  which  arches  over  the  longi- 
tudinal fissure. 

The  liver  has  five  ligaments,  of  which  the  coronary,  the  right 
and  left  lateral,  and  the  falciform  are  reflections  of  the  peritoneum  ; 
the  fifth  is  the  round  ligament  in  the  anterior  free  border  of  the 
falciform  ligament ;  it  consists  of  the  remains  of  the  umbilical 
vein.  The  ligaments  have  been  previously  described  (p.  377). 

FIG.  107. 


1.  Longitudinal  fis- 
sure. 

?.  Continuation  of 
the  longitudi- 
nal fissure  (for 
the  ductus  ve- 
nosus). 

3,  Transverse  fis- 
sure. 

4.  Gall-bladder. 


5.  Venacavainits 

groove. 

6.  Right  lobe. 

7.  Left  lobe. 

8.  Lobulus  Spigelii. 

9.  Lobulus  cauda- 

tns. 

10.  Lobulus     quad- 
rat us. 


DIAGRAM    OF    THE    UNDEB    SURFACE    OF   THE   LITEH. 

The  liver  is  surrounded  by  a  thin  areolar  coat  or  capsule,  best 
seen  on  those  parts  of  it  not  covered  with  peritoneum.  This  coat 
is  connected  to  the  areolar  tissue  which  surrounds  the  lobules, 
but  does  not  send  down  partitions  to  form  a  framework  for  the 
interior  of  the  gland.  It  is  continuous,  at  the  transverse  fissure, 
with  the  sheath  of  loose  areolar  tissue  called  Glisson's  capsule, 
which  surrounds  the  vessels  as  they  enter  that  fissure,  and  in- 
closes them  in  a  common  sheath  in  their  ramifications  through 
the  liver. 

The  inter-lobular  areolar  tissue  is  exceedingly  delicate ;  hence 


478 


STRUCTURE    OF    THE    LIVER. 


LOBULES. 


the  great  liability  of  the  liver  to  be  lacerated  by  external  violence, 
or  by  the  action  of  the  abdominal  muscles. 

The  liver  consists  of  an  aggregation  of  small 
polyhedral  masses  called  lobules,  which  range  from 
an  inch  in  diameter.  These  lobules  are  marked 
out  by  septa  of  areolar  tissue,  and  in  a  transverse  section  have  the 
appearance  of  mosaic  pavement  (fig.  108) ;  but  in  a  perpendicular 
section  they  somewhat  resemble  an  oak-leaf  (fig.  109).  Each 
lobule  consists  of  a  minute  plexus  of  blood-vessels,  ducts,  and  cells 


To  of 


«.  Inter-lobular  vein. 


6.  Intra-lobular   or  cen- 
tral vein. 


TRANSVERSE    SECTIONS    OF    THREE   LOBULES    OF    THE    LITER,    MAGNIFIED    TO   SHOW 
THE    POBTAL    VENOUS    PLEXUS. 

(After  Kiernan.) 

— hepatic  cells — which  latter  fill  up  the  spaces  between  the  rami- 
fications of  the  vessels.  It  will  facilitate  the  understanding  of  the 
branchings  of  the  different  hepatic  vessels,  if  it  be  borne  in  mind, 
1,  that  the  portal  vein,  hepatic  artery,  and  hepatic  duct,  ramify 
together  from  first  to  last — inclosed  in  a  sheath  of  areolar  tissue, 
called  Glissori's  capsule ;  2,  that  the  hepatic  veins  run  alone  from 
first  to  last,  and  terminate  in  the  inferior  vena  cava  as  it  passes 
under  the  liver. 

The  portal  vein,  on  entering  the  substance  of  the  liver,  gives 
off  numerous  small  branches,  which  pass  between  the  lobules  and 


STRUCTURE    OF   THE    LIVER. 


479 


LONGITUDINAL  SECTIONS  OF  THB 
LOBULES  OF  THE  L1VEB.  INTRA- 
LOBULAB  TEINS  SEEN  JOINING  THE 
STJB-LOBULAB. 


form  the  inter-lobular  or  peripheric  veins  (fig.  108).     The  inter- 

lobular   veins   give    off    a    minute  FIG.  109. 

capillary  network  which  penetrates 

into  the  interior  of  the  lobules  and 

freely  communicates  in  the   centre 

with  a  single  trunk  called  the  intra- 

lobular  or  central  vein.     This  cen- 

tral vein  returns  the  blood  from  the 

lobule,  and  opens  immediately  into 

a  sub-lobular  vein,  larger  or  smaller 

as  the  case  may  be,  upon  which  the 

lobule  is  sessile  (fig.  109)..  The  sub- 

lobular  veins  empty  themselves  into   the  smaller  hepatic  veins  ; 

these  unite  to  form  the  main  hepatic  trunks  which  open  into  the 

inferior  vena  cava. 

The  hepatic  artery  Centering  the  liver  at  the  transverse  fissure, 
divides  and  subdivides  with  the  portal  vein  and  the  biliary  ducts, 
and  ramifies  with  them  between  the  lobules.  The  artery  distri- 
butes branches  which  supply  the  coats  of  the  hepatic  vessels  and 
Grlisson's  capsule  —  vaginal  branches  —  and  the  capsule  of  the  liver 
—  capsular  branches  ;  other  branches  pass  into  the  lobules  and 
join  the  capillary  network  which  leads  to  the  radicles  of  the  cen- 
tral vein. 

The  minute  capillary  network  which  forms  the  basis  of  the 
lobule  radiates  from  the  periphery  to<the  centre.  The  capillaries 
average  about  -^  sVo  °^  an 


The  biliary  ducts  form  a  close  network  round  the  circum- 
ference of  each  lobule.  From  this  network  of  biliary  capillaries 
branches  proceed  on  all  sides,  and  accompany  the  portal  vein. 
Doubt  still  exists  as  to  the  commencement  of  the  ducts.  The 
prevalent  opinion  is  that  they  begin  within  the  lobules  by  a  minute 
plexus,  surrounded  by  hepatic  cells.  The  interior  of  each  lobule  — 
that  is,  the  space  left  between  the  several  vessels  —  is  filled  by  the 
hepatic  cells.  They  are  nucleated,,  and  have  a  diameter  vary- 
ing from  g-i-o-  to  j-oVo  °f  an  incn-  They  contain  more  or  less 
granular-matter,  and  in  some  cases  fat-globules  :  when  these 


480  STKTTCTUBE    OF   THE    LIVEE. 

accumulate  in  large  quantities,  they  constitute  what  is  called  a 
fatty  liver.  The  office  of  these  cells  is  to  separate  the  bile  from 
the  blood,  and,  when  filled  with  bile,  to  discharge  their  contents 
into  the  hepatic  ducts.* 

The  lymphatics  of  the  liver,  superficial  and  deep,  commence 
in  the  spaces  in  the  interior  of  the  lobule,  accompany  the  inter- 
lobular  vessels,  and  pass  out  at  the  transverse  fissure.  The 
superficial  lymphatics  are  in  connection  with  the  areolar  sheath 
and  the  upper  surface  of  the  liver. 

The  nerves  of  the  liver  are  derived  from  the  pneumogastric, 
chiefly  the  left ;  and  from  the  hepatic  plexus  which  comes  from 
the  cceliac  plexus.  These  plexuses  enter  the  liver  at  the  trans- 
verse fissure,  surround  the  hepatic  artery  and  the  portal  vein,  and 
accompany  these  vessels  in  their  ramifications  through  it.  The 
ultimate  termination  of  these  nerves  is  not  known. 

The  functions  of  the  liver  may  be  thus  briefly  expressed: — 
1 .  It  renders  the  albuminous  matter  (albuminose)  brought  to  it  by 
the  portal  vein  capable  of  being  assimilated.  2.  It  forms  a  sub- 
stance, glycogen,  easily  converted  into  sugar,  which  passes  into  the 
hepatic  veins,  and  being  consumed,  helps  to  maintain  animal  heat. 
3.  It  secretes  the  bile,  which  assists  in  converting  the  chyme  into 
chyle,  and  reducing  it  into  a  state  fit  to  be  absorbed  by  the  lac- 
teals.  4.  The  bile  acts  as  a  natural  aperient.  5.  The  bile  is  an 
antiseptic,  and  probably  prevents  the  decomposition  of  the  food 
during  its  passage  through  the  intestine. 

The   gall-bladder,  or  reservoir  for  the  bile,  is 

GALL-BLADDER.  °  . 

confined  by  the  peritoneum  in  a  slight  depression 

on  the  under  surface  of  the  right  lobe  of  the  liver  (p.  477).  It  is 
pyriform  in  shape,  is  about  four  inches  long,  and  capable  of  hold- 
ing about  1  ^  oz.  of  fluid.  Its  narrow  end,  or  neck,  makes  a  bend 
downwards,  and  terminates  in  a  duct,  called  the  cystic,  which, 
after  a  course  of  about  an  inch  and  a  half,  joins  the  hepatic  duct 
at  an  acute  angle  (fig.  81,  p.  387).  The  common  duct,  ductus 
communis  choledochus,  formed  by  their  union,  is  about  three  or 

*  For  further  information  on  this  subject  see  the  original  observations  of  Kiernan 
in  the  '  Philosoph.  Trans.'  for  1833. 


STRUCTURE  OF  THE  SPLEEN.  481 

four  inches  long,  and  opens  into  the  back  of  the  descending  part 
of  the  duodenum,  after  running  very  obliquely  through  the  coats  of 
the  bowel. 

Exclusive  of  its  partial  peritoneal  covering,  the  gall-bladder 
has  two  coats  :  the  outer,  consisting  of  connective  tissue,  contains 
involuntary  muscular  fibres,  which  run  mainly  in  the  long  axis  of 
the  gall-bladder;  the  inner  is  the  mucous  coat. 

It  is  supplied  with  blood  from  the  cystic  branch  of  the  right 
hepatic  artery;  its  blood  is  returned  by  the  cystic  vein  which 
opens  into  the  vena  portse ;  its  nerves  are  derived  from  the  cystic 
branches  of  the  hepatic  plexus. 

The  gall-bladder  should  now  be  laid  open.  Its  mucous  mem- 
brane is  generally  tinged  yellow  by  bile,  and  gathered  into  ridges 
which  give  it  a  honey-combed  appearance.  This  appearance  is 
most  marked  in  the  middle  of  the  gall-bladder:  in  the  de- 
pressions between  the  ridges  may  be  seen,  with  a  lens,  numerous 
openings  leading  down  to  mucous  follicles.  It  is  covered  by 
columnar  epithelium,  which  secretes  an  abundance  of  viscid 
mucus.  At  the  bend  of  the  neck  of  the  gall-bladder,  both  its 
coats  project  very  much  into  the  interior,  making  the  opening 
considerably  narrower  than  it  appears  to  be  outside.  In  the  cystic 
duct,  the  mucous  membrane  presents  a  series  of  folds,  so  arranged, 
one  after  the  other,  as  to  form  a  complete  spiral  valve.  The  pro- 
bable use  of  this  is  to  prevent  the  too  rapid  flow  of  the  bile.  The 
gall-bladder  appears  to  serve  mainly  as  a  reservoir  for  the  bile, 
while  digestion  is  not  going  on.  The  bile  becomes  during  its 
.sojourn  in  the  gall-bladder  very  viscid  and  intensely  bitter. 

The  spleen  is  a  very  vascular  sponge-like  organ, 
and  belongs  to  the  class  of  ductless  glands.  It 
varies  in  size  according  to  the  amount  of  blood  in  it,  fluctuating 
in  weight,  consistently  with  health,  between  five  and  ten  ounces. 
It  is  of  a  reddish-blue  colour.  It  is  more  or  less  elliptical  in  shape, 
and  in  its  natural  position  is  placed  with  its  long  axis  nearly 
vertical.  Its  outer  surface,  which  corresponds  to  the  ninth,  tenth, 
and  eleventh  ribs,  is  adapted  to  the  diaphragm  and  ribs,  and  is 
smooth  and  convex;  its  inner,  adapted  to  the  great  end  of  the 

i  i 


482  STRUCTURE  OP  THE  SPLEEN. 

stomach,  is  concave,  and  divided  into  an  anterior  and  a  posterior 
portion  by  a  vertical  fissure — the  hilus — at  the  bottom  of  which 
are  large  openings  through  which  the  vessels  enter  and  emerge 
from  the  spleen. 

The  spleen  is  invested  with  two  coats,  a  peritoneal  and  a 
fibrous.  The  peritoneal  coat  entirely  covers  the  organ,  except  at 
the  hilus,  from  which  it  is  reflected  to  the  stomach,  forming  the 
gastro-splenic  omentum.  Its  fibrous  capsule,  tunica  propria, 
not  only  covers  the  spleen,  but  sends  throughout  its  substance 
fibrous  cords  (trabeculoe),  which  cross  in  various  directions,  and 
thus  form  an  intricate  network  of  what  are  called  trabecular  spaces. 
Besides  this,  the  "trabeeulse  form  sheaths  and  supports  for  the  splenic 
vessels  throughout  their  ramifications.  The  whole  of  this  fibrous 
framework  is  exceedingly  elastic  to  admit  of  the  varying  size  of  the 
spleen,  and  contains  more  or  less  non-striped  muscular  tissue. 

The  trabecular  spaces,  above  described,  are  filled  with  what  is 
called  the  pulp  ^)f  the  spleen.  This  pulp  is  a  soft  reddish-brown 
substance,  and,  under  the  microscope,  is  found  to  consist  of  con- 
nective-tissue corpuscles,  which,  with  their  communicating  pro- 
cesses, make  up  a  fine  retiform  tissue,  the  interstices  between  which 
are  filled  with  red  and  white  blood-corpuscles.  Broadly  speaking, 
then,  the  spleen  pulp  is  composed  chiefly  of  cells. 

The  splenic  artery  enters  at  the  hilus  of  the  spleen,  by  several 
branches,  which  ramify  in  its  substance  ensheathed  and  supported 
by  the  fibrous  framework*  The  smallest  branches  leave  the 
trabeculse,  and,  entering  the  splenic  pulp,  terminate  in  minute 
vessels,  arranged  in  pennicillate  tufts.  They  open,  and  therefore 
pour  their  blood  directly,  into  the  pulp  tissue.  The  veins  are  said 
to  commence  in  the  pulp  tissue  in  the  same  way  as  the  arteries 
terminate  in  it,  and  to  travel  along  the  trabeculse  like  the  arteries  ; 
but  they  communicate  freely,  and  are  so  far  unlike  the  arteries. 

In  the  pulp  of  the  spleen  we  also  find  what  are  called  the 
Malpighian  corpuscles.-f  They  are  about  -^  of  an  inch  in 

*  The  ramifications  of  the  splenic  artery  may  be  seen  by  washing  away  the  pulp, 
and  floating  the  flocculeat-looking  spleen  in  water. 

•{•  It  is  useless  to  lojk  for  them  in  the  human  spleen,  unless  the  subject  be  ei- 


STRUCTURE    OP    THE    KIDNEY.  483 

diameter,  visible  to  the  naked  eye,  and  look  like  white  spots  scat- 
tered through  the  dark  pulp.  They  are  attached  to  the  sides  of 
the  arteries,  and  are  said  to  be  lymphoid  expansions  of  the  con- 
nective tissue  coat  or  outside  coat  of  the  arteries.  These  curious 
spherical  bodies  are  filled  with  lymph-corpuscles.  They  appear 
not  to  have  definite  boundaries,  but  to  communicate  freely  with 
the  reticular  spaces  of  the  pulp. 

The  lymphatics  of  the  spleen  run  between  the  layers  of  the 
gastro-splenic  omentum  to  the  lymphatic  glands. 

The  function  of  the  spleen  is  not  yet  accurately  ascertained. 
It  appears  to  be,  essentially,  a  great  blood-gland ;  and  that  it 
consists  of  chambers  filled  with  gland- cells  of  various  size, 
between  which  ramify  minute  arteries  and  veins.  It  is  pre- 
sumed that  the  gland  elaborates  the  albuminous  materials  of 
food,  and  stores  them  up  for  a  time  before  they  pass  into 
the  blood.  It  is  considered  to  be  a  nursery  for  the  production 
of  the  white  corpuscles  of  the  blood ;  and  a  grave-yard  too,  where 
many  of  the  worn-out  red  ones  undergo  disintegration. 

The  kidneys,  two  in  number,  are  situated  in 
-the  lumbar  region,  embedded  in  fat.  Their 
colour  is  reddish-brown.  Each  is  about  4  inches  in  length,  and 
2£  inches  in  breadth,  and  weighs  about  4^  ounces  in  the  male, 
rather  less  in  the  female.  The  left,  usually  situated  higher 
than  the  right,  is  generally  longer  and  somewhat  heavier. 
The  anterior  surface  of  each  is  smooth  and  convex ;  the  posterior 
rather  flattened.  The  upper  end  of  the  kidney  is  larger  and 
thicker  than  the  lower ;  the  outer  border  is  rounded ;  the  inner 
presents  a  deep  notch — the  hilus — for  the  entrance  and  exit  of 
the  renal  vessels  and  duct.  These  have  the  following  relations 
to  one  another  :  in  front  lies  the  renal  vein  ;  behind  is  the  ureter  ; 
between  is  the  renal  artery. 

The  kidney  is  surrounded  by  a  thin  fibrous  capsule,  to  which 
it  is  loosely  connected  by  areolar  tissue  and  minute  vessels.  The 

ceedingly  fresh,  for  they  soon  soften  and  melt  in  the  pulp.  It  is  better,  therefore,  to 
examine  them  in  the  spleen  of  a  sheep  or  bullock,  in  which  animals  they  are  about  J. 
of  an  inch  in  diameter. 

I  i  2 


484 


STRUCTURE    OF   THE   KIDNEY. 


FIG.  110. 


capsule  does  not  penetrate  into  the  interior  of  the  kidney,  and 
can  be  readily  stripped  off  when  healthy,  leaving  the  surface 
perfectly  smooth. 

A  longitudinal  section  should  be 
made  through  the  kidney  to  ex- 
amine its  interior.  This  section 
displays  two  distinct  substances, 
an  outer  or  cortical,  and  an  inner 
or  medullary. 

The  medullary  structure  is  col- 
lected into  from  ten  to  sixteen 
pyramidal  bundles  (pyramids  of 
Malpighi,*  fig.  110);  the  apices 
of  these,  termed  papillae,  project 
into  one  of  the  terminal  divisions 
of  the  excretory  tube.  The  pyra- 
mids are  surrounded  by  the  cor- 
tical substance  which  dips  down 
between  them  ;  they  are  composed 
of  minute  straight  tubes,  which 
proceed  from  the  cortical  portion 
to  end  on  the  papillae. f 

The  cortical  structure  is  deeper 
in  colour  than  the  medullary, 
forms  the  outer  part  of  the  kidney,  and  dips  down  between  the 
pyramids.  It  consists  of  convoluted  tubes,  which  become  dilated 
at  their  extremities  into  what  are  called  the  Malpighian  capsules. 
At  the  hilus  is  the  dilated  commencement  of  the  ureter,  called 
the  pelvis  of  the  kidney.  It  is  funnel-shaped,  and  its  broad  part 
divides  into  two  principal  channels,  which  again  branch  and  form 

*  So  named  after  Malpighi,  a  celebrated  Italian  anatomist  who  lived  during  the 
middle  and  latter  part  of  the  seventeenth  century. 

f  Each  pyramid  represents  what  was,  in  the  early  stage  of  the  kidney's  growth, 
a  distinct  and  independent  lobe.  In  the  human  subject  the  lobes  gradually  coalesce, 
and  no  trace  of  their  primordial  state  remains,  except  the  pyramidal  arrangement  of 
the  tubes.  But  in  the  kidneys  of  the  lower  mammalia,  of  birds  and  reptiles,  the 
lobes  are  permanently  separate. 


SECTION    OF   THE    KIDNEY. 


1.  Ureter. 

2.  Pelvis  of  the  kidney. 

3.  3,  3.  Papulae. 


STRUCTURE  OP  THE  KIDNEY. 


485 


from  eight  to  twelve  cup-like  excavations,  called  the  calyces.  Into 
each  of  these  calyces  one,  sometimes  two  or  more  papillae  project. 
Between  the  calyces  the  branches  of  the  renal  artery  ascend  to 
ramify  in  the  kidney,  lying  embedded  in  fat.  With  a  lens,  the 
papillae  may  be  seen  studded  with  minute  apertures,  which  are 

FIG.  111. 


1.  Malpighian  capsule. 

2.  Convoluted  tube. 

3.  Descending  limb. 

4.  Ascending    limb    of 

Henle's  loop. 

5.  Junctional  tube. 


6,  7.  Different  portions  of 

straight  tube. 
8.  Excretory  tube. 

a.  Apex  ol  pyramid. 

b.  Base  of  pyramid. 
C.  Cortical  portion. 


DIAGRAM    OF   THE    COURSE   AND   ARRANGEMENT   OF   THE    URINIFEROUS   TUBES. 

(Ludwig.) 

the  terminations  of  the  uriniferous  tubes.  These  tubes  as  they 
pass  outwards  run  straight,  bifurcate  repeatedly  at  very  acute 
angles,  and  reach  the  sides  and  the  bases  of  the  pyramids.  They 
then  enter  the  cortex  in  bundles  of  straight  tubes,  forming  the 
pyramids  of  Ferrein.  They  vary  from  the  -^-^th  to  the  -^  Oth  of 


486 


STRUCTURE    OF    THE    KIDNEY. 


an  inch  in  diameter,  and  are  largest  towards  their  termination.  On 
entering  the  cortex,  the  tubes  become  convoluted,  and  are  sur- 
rounded by  minute  plexuses  of  blood-vessels.  The  tubuli  uriniferi, 
the  pelvis  of  the  kidney,  and  the  ureter,  are  lined  by  spheroidal 
epithelium.  Between  the  straight  tubes  in  the  Malpighian 
pyramids,  there  have  been  discovered  numerous  smaller  tubules, 
named  the  looped  tubes  of  Henle.  These  come  off  from  the 
straight  tubes  in  the  cortical  portion,  descend  towards  the  apex  of 
the  pyramid,  where  they  form  loops,  and  again  ascend  to  terminate 
in  the  Malpighian  capsules. 

The  Malpighian  capsules  are  situated  in  the  cortical  portion, 
average  about  y^th  of  an  inch  in  diameter,  and  are  visible  to  the 
naked  eye  as  minute  red  points.  According 
to  Bowman,*  each  is  formed  by  the  dilatation 
of  the  uriniferous  tube.  It  is  composed  of  a 
homogeneous  membrane,  and  is  pierced  by  a 
small  artery,  afferent  vessel,  which  enters  the 
capsule  opposite  to  the  commencement  of  the 
urinary  tube.  In  the  capsule  the  artery  breaks 
up  into  a  coil  of  minute  vessels,  glomerulus, 
and  returns  its  blood  by  a  vein  (efferent  vessel), 
which  emerges  from  the  capsule  close  to  where 
the  artery  entered  (fig.  112).  Instead  of  leaving 
^ne  kidney,  as  in  other  organs,  the  vein  forms  a 
c  '  catsuit  efferent  vesse1'  plexus  round  the  convolutions  of  the  urinary 
a.  urinary  tube.  tube.f  The  purpose  of  this  plexus  appears  to 

be  the  secretion  of  the  solid  matter  of  the  urine;  while  the  Malpig- 
hian body  filters  the  watery  part  of  the  urine  into  the  capsule, 
and  washes  the  mere  solid  part  down  the  tube.|  The  coil  of  vessels 

*  '  Philosoph.  Trans.'  for  1842  ;  part  i. 

f  For  a  summary  of  the  opinion  held  by  various  observers,  respecting  these  Mal- 
pighian corpuscles,  consult  a  paper  by  E.  Southej,  M.D.,  '  St.  Bartholomew's  Hosp. 
Reports,'  vol.  i.  1865. 

J  That  the  vessel  leaving  the  Malpighian  body  is  a  vein,  and  that  a  constituent 
part  of  the  urine  is  secreted  by  venous  blood,  is  inferred  from  two  reasons:  1.  From 
the  analogous  case  of  the  vena  portse,  out  of  which  the  bile  is  elaborated  in  the  liver  ; 
2.  from  the  fact  that  in  reptiles  the  urine  is  secreted  from  venous  blood. 


a  Artery 


STRUCTURE  OF  THE  SUPRA-RENAL  CAPSULES.      487 

in  the  capsule  is  surrounded  by  the  epithelium  lining  the  interior 
of  the  capsule. 

The  renal  artery  enters  the  hilus  between  the  pelvis  -and  the 
renal  vein.  It  shortly  divides  into  four  or  five  branches,  which 
pass  outwards  between  the  papillae,  and  then  enter  the  cortical 
portion  between  the  pyramids.  In  this  portion  they  ascend  as  far 
as  the  bases  of  the  pyramids,  and  then  coursing-  along  their  bases 
they  form  arches  between  the  cortical  and  medullary  structure, 
from  which  small  vessels  are  given  off,  which  pass  to  the  Mal- 
pighian  capsules. 

The  nerves  forming  the  renal  plexus  are  derived  from  the 
lesser  splanchnic  nerve  and  the  solar  plexus.  The  lymphatics, 
consisting  of  a  deep  and  a  superficial  set,  pass  to  the  lumbar 
glands. 

SUPBA-EENAL  These  bodies,'situated  at  the  top  of  the  kidneys, 

CAPSULES.  belong  to  the  class  of  ductless  glands.     The  right 

resembles  a  cocked  hat ;  the  left  is  more  almond-shaped.  They 
measure  about  1^  inch  in  their  long  diameter,  and  weigh  from  one 
to  two  drachms.  They  are  surrounded  by  a  thin  fibrous  covering, 
which  sends  down  partitions  into  the  interior  through  furrows  upon 
their  surface. 

A  perpendicular  section  shows  that  it  consists  of  a  firm  exterior 
or  cortical  part,  and  of  an  interior  or  medullary  substance,  soft  and 
pulpy.  The  cortical  portion  is  of  a  yellow  colour,  and  forms  the 
principal  part  of  the  organ.  Examined  under  the  microscope,  it 
appears  to  be  composed  of  a  delicate  fibrous  stroma,  in  which 
run  parallel  columns  of  cells  about  y^th  of  an  inch  in  diameter, 
arranged  perpendicularly  to  the  surface.  These  columns  do  not 
run  completely  through  the  thickness  of  the  cortical  portion, 
but  have  a  zone  of  cells  arranged  above  and  below  them.  The 
columns  are  stated  by  some  to  be  tubes  having  a  distinct 
lining  membrane;  by  others,  to  be  closed  vesicles;  by  others, 
to  be  cavities  in  the  cortical  portion.  Small  arteries  are  abun- 
dantly supplied  to  the  cortex,  and  dip  down  between  the  columns. 
The  medullary  part  varies  in  colour  according  to  the  amount  of 
blood  contained  in  it,  being  sometimes  of  a  dark-brown  colour, 


488  STEUCTURE  OF  THE  STOMACH. 

sometimes  nearly  white.  It  consists  of  a  plexus  of  minute  veins, 
among  which  are  numerous  cells,  some  of  which  appear  branched.* 
The  stroma  is  composed  of  areolar  tissue,  which  forms  a  delicate 
network  throughout  the  central  part. 

The  supra-renal  capsules  are  well  supplied  with  nerves  derived 
from  the  solar  and  renal  plexuses  of  the  sympathetic.  Of  late 
years  the  minute  structure  and  functions  of  the  supra-renal 
capsules  have  been  much  investigated,  in  consequence  of  the  dis- 
covery, made  by  Dr.  Addison,  of  the  close  relation  which  exists 
between  certain  diseases  in  these  bodies  and  a  brown  discolouration 
of  the  skin.  Their  precise  function  is  still  unknown. 

STOMACH  AND  The  alimentary  canal  is  composed  of  four  coats  ; 

INTESTINE.  a  serous,  a  muscular,  a  submucous,  and  a  mucous. 

First,  is  the  serous  or  peritoneal  coat,  described  at  p.  379. 
Secondly,  under  the  serous  is  a  muscular  coat,  upon  which  the 
chief  strength  of  the  canal  depends.  It  consists  of  two  distinct 
strata  of  plain  muscular  fibres  ;  the  outer  stratum  is  longitudinal, 
the  inner  circular.  This  arrangement  not  only  makes  the  bowel 
stronger,  but  regulates  its  peristaltic  action  :  for  the  longitudinal 
fibres,  by  their  contraction,  tend  to  shorten  and  straighten  the 
tube,  while  the  circular  fibres  contract  upon  and  propel  its  con- 
tents to  greater  advantage.  Connecting  this  coat  and  the  mucous, 
is  a  layer  of  areolar  tissue  called  the  submucous  coat,  in  which 
the  arteries  break  up  before  entering  the  mucous  membrane.  The 
mucous  is  the  most  complicated  of  all  the  coats,  for  it  presents 
different  characters  in  different  parts,  according  to  the  functions 
which  it  has  to  perform. 

The  stomach  should  be  moderately  distended 
STOMACH.  . 

to  see  its  size,  which  varies  in  different  subjects 

according  to  the  habits  of  the  individual.  When  distended,  an 
average  stomach  would  be  about  ten  or  twelve  inches  in  length 
and  four  in  width.  The  stomach  forms  a  large  bulge  to  the  left 
of  the  oesophagus,  called  the  cardiac  or  splenic  end  :  on  the 
right  side,  where  the  food  passes  out,  it  becomes  small  and  con- 

*  Consult  '  A  Physiological  Essay  on  the  Thymus  Gland,'  by  Simon :  London, 
1845. 


STRUCTURE  OF  THE  STOMACH.  489 

tracted,  and  is  called  the  pyloric  end.  Just  before  the  pylorus, 
the  stomach  bulges  into  a  pouch,  called  antrum  pylori.  Anato- 
mists describe  the  stomach  as  having  two  borders  and  two  sur- 
faces. The  upper  border  is  concave,  and  called  the  lesser  curve : 
the  lower  border  is  convex,  and  called  the  greater  curve.  On 
removing  the  serous  investment  of  the  stomach,  the  muscular 
coat  is  exposed.  The  fibres  are  of  the  non-striped  variety,  and 
arranged  in  three  layers,  an  external  or  longitudinal,  a  middle  or 
circular,  and  an  internal  or  oblique. 

The  longitudinal  fibres  are  continuous  with  the  longitudinal 
fibres  of  the  oesophagus,  and  spread  out  over  the  stomach :  they 
are  most  numerous  along  the  curves  of  the  stomach.  The  circular 
fibres  are  well  marked  about  the  middle  of  the  stomach,  but  are 
most  abundant  at  the  pylorus,  where  they  form  a  powerful  sphincter. 
The  oblique  fibres  are  scattered  over  the  sides  of  the  stomach,  and 
are  most  distinct  at  the  entrance  of  the  ossophagus,  with  the 
well-marked  circular  fibres  of  which  they  are  continuous. 

When  the  stomach  is  laid  open,  the  mucous  membrane  is  seen 
to  be  of  a  pale  colour,  and  gathered  into  longitudinal  folds — rugce 
— which  disappear  when  the  stomach  is  full.  The  mucous  mem- 
brane is  connected  to  the  muscular  layer  by  a  distinct  stratum  of 
areolar  tissue,  called  the  submucous  coat.  It  permits  the  mus- 
cular and  mucous  coats  to  move  freely  on  each  other,  and  serves 
as  a  bed,  in  which  the  blood-vessels  ramify  minutely  before  they 
enter  the  mucous  membrane. 

If  a  portion  of  the  mucous  membrane  be  examined  under  a 
microscope,  its  surface  will  be  seen  to  be  mapped  out  into  small 
hexagonal  pits  or  alveoli,  giving  it  a  honey-combed  appearance. 
The  pits  vary  from  the  y^-g-  to  -^fa  of  an  inch  in  diameter.  At  the 
bottom  of  them  are  a  number  of  minute  pores,  the  orifices  of  the 
gastric  tubes.  In  a  perpendicular  section,  the  tubes  are  arranged 
in  parallel  lines  at  right  angles  to  the  surface,  and  terminate  in 
blind  sacculated  ends  set  in  the  submucous  tissue.  The  entire 
thickness  of  the  mucous  membrane  is  made  up  of  these  tubular 
glands.  The  tubules  are  on  an  average  about  -^  of  an  inch  long 
and  the  -^-^  of  an  inch  in  diameter.  In  the  cardiac  end  they  are 


490         STEUCTUEE  0$  THE  SMALL  INTESTINE. 

simple  tubes,  but,  at  the  pyloric,  they  are  frequently  branched. 
Their  upper  fourth  is  lined  with  columnar  epithelium  ;  their  lower 
three-fourths,  with  spheroidal  or  glandular.  It  is  presumed  that 
these  glandular  cells  contain  the  gastric  juice.  As  fast  as  formed, 
during  digestion,  they  pass  into  the  stomach,  discharge  their  con- 
tents, and  disappear.  Other  glands — pyloric — are  found  near  the 
pyloric  end  of  the  stomach,  and  are  probably  mucous  glands.  There 
are  also  glands  more  numerous  than  these,  called  peptic  glands. 
They  are  lined  for  a  short  distance  with  columnar  epithelial  cells, 
which  at  the  neck  become  spheroidal  and  granular,  and  are  called 
peptic  cells ;  towards  the  lower  part  or  fundus  of  the  gland  the 
cells  are  only  found  here  and  there,  and  cause  a  more  or  less  bulging 
of  the  basement  membrane. 

The  mucous  membrane  of  the  stomach  is  lined  by  columnar 
epithelium.  It  is  exceedingly  thin  and  delicate,  and  can  only  be 
seen  in  the  stomach  of  an  animal  recently  killed. 

The  tubes  of  the  stomach  are  richly  supplied  with  blood.  The 
arteries  form  a  stratum  of  minute  inosculations  in  the  submucous 
tissue,  in  which  the  closed  ends  of  the  tubes  are  set ;  from  this 
stratum  the  vessels  run  up  between  the  tubes  to  the  surface  of  the 
stomach,  where  they  again  inosculate,  and  form  the  hexagonal 
spaces  before  alluded  to. 

The  stomach  is  supplied  with  nerves  from  the  pneumogastric 
and  from  the  solar  plexus. 

SMALL  The  small  intestine,  consisting  of  the  duodenum, 

INTESTINE.  jejunum,  and  ileum,  forms  a  tube  from  sixteen  to 

twenty-six  feet  in  length,  according  to  the  height  of  the  individual. 
The  duodenum  is  about  twelve  fingers'  breadth  in  length  ;  the 
jejunum  comprises  two-fifths,  the  ileum  three-fifths,  of  the  remain- 
ing part  of  the  small  intestine.  As  regards  their  external  cha- 
racter, the  duodenum  and  jejunum  are  more  vascular  than  the 
ileum,  and  feel  thicker  in  consequence  of  the  peculiar  arrangement 
of  their  mucous  membrane  ;  but  there  are  no  defined  limits  between 
the  different  portions  of  the  intestinal  canal.  Its  peritoneal  and 
muscular  coats  are  the  same  throughout.  The  muscular  coat 
consists  of  an  outer  longitudinal  layer  and  an  inner  circular  thicker 


STRUCTURE  OP  THE  SMALL  INTESTINE.         491 

layer,  which,  however,  becomes  thinner  towards  the  end  of  the  ileum. 
It  is  connected  to  the  mucous  membrane  by  the  submucous  coat. 
Immediately  beneath  the  mucous  membrane  there  is  a  very  thin 
layer  of  non-striped  muscular  fibre,  termed  muscularis  mucosce. 

When  the  small  intestine  is  cut  open  from  the  upper  end, 
we  see  that  the  mucous  membrane  is  arranged  in  close  transverse 
folds,  called  valvulce  conniventes.  These  differ  from  other  folds 
in  the  alimentary  canal — e.g.  in  the  oesophagus  and  stomach —  in 
that  they  are  not  obliterated  when  the  tube  is  distended.  Each  fold 
extends  about  one-half  or  two-thirds  round  the  intestine  ;  but 
they  are  not  all  of  equal  size.  They  commence  immediately 
below  the  opening  of  the  biliary  and  pancreatic  ducts,  and  are 
most  developed  in  the  duodenum  and  the  upper  part  of  the 
jejunum.  Below  this  part  of  the  tube  they  gradually  decrease 
in  size,  and  become  wider  apart,  till  they  finally  disappear  near 
the  middle  of  the  ileum.  The  use  of  the  valvulse  conniventes 
is  to  increase  the  extent  of  surface  for  the  absorption  of  chyle ; 
to  prevent  the  food  passing  too  rapidly  through  the  intestine, 
and  for  secretion. 

If  a  portion  of  small  intestine  be  washed  and  placed  in  water, 
the  surface  of  the  mucous  membrane  appears  like  the  soft  fur  or 
pile  upon  velvet.  This  appearance  is  produced  by  small  processes 
called  villi.  These  are  extremely  vascular  projections  of  the 
mucous  membrane,  about  a  fourth  of  a  line  in  length,  and  are 
so  numerous  that  a  square  line  contains  from  forty  to  ninety  of 
them.*  Their  size,  however,  and  their  number,  bear  a  direct  ratio 
to  that  of  the  valvulse  conniventes.  Under  the  microscope  a  villus 
is  seen  to  consist  of  an  outstanding  process  of  the  mucous  mem- 
brane, covered  by  a  layer  of  columnar  epithelium,  which  rests  upon 
a  basement  membrane.  Each  villus  is  furnished  with  an  artery 
which  forms  a  network  of  inosculations  in  it,  and  then  returns  its 
blood  by  a  single  vein.  Down  its  middle  runs  a  lacteal  or  absorb- 
ing vessel,  which  commences  in  a  closed  end  near  the  summit  of 
the  villus,  where  it  is  surrounded  by  a  layer  of  pale  non-striped 
muscular  fibres  proceeding  from  the  muscularis  mucosce.  The 
*  Krause  estimates  the  total  number  of  villi  at  four  millions. 


492  STRUCTURE    OF   THE    SMALL   INTESTINE. 

cylindrical  cells  which  cover  the  villi  are  believed  to  be  the  agents 
in  the  absorption  of  the  chyle,  and  to  possess  the  power  of  selection. 
INTESTINAL  There  are  four  kinds  of  glands*  in  the  small  in- 

GLANDS.  testine,  called  the  glands  of  Lieberkiihn,  Brunner, 

Peyer,  and  the  solitary  glands.  The  first  and  last  are  distributed 
over  the  whole  tract  of  the  intestinal  mucous  membrane ;  the  other 
two  over  particular  parts. 

The  glands  of  LieberkuhnJ  the  most  numerous  of  all,  are 
minute  tubes  with  blind  ends,  very  thickly  distributed  over  the 
small  and  the  large  intestines.  Under  the  microscope,  their 
orifices  are  seen  between  the  villi,  like  so  many  minute  dots. 
These  vary  in  depth  from  -^  to  -^  of  a  line,  and  about  the  J^  of 
a  line  in  diameter,  and  are  lined  with  columnar  epithelium. 

The  glands  of  Brunner  \  are  found  only  in  the  duodenum. 
They  are  just  visible  to  the  naked  eye,  and  may  be  seen  by  re- 
moving the  muscular  coat.  Their  structure  exactly  resembles  the 
'  round  compound  glands  of  the  mucous  membrane  of  the  mouth. 

The  glands  of  Peyer  §  (glandulse  agminatse)  abound  most  in 
the  ileum,  and  are  seen  most  distinctly  in  children.  They  are 
arranged  in  groups,  from  twenty  to  forty  in  number,  on  that  part 
of  the  intestine  most  distant  from  the  attachment  of  the  mesen- 
tery. These  groups  are  from  half  an  inch  to  three  inches  long,  of 
an  oval  form,  and  increase  in  size  and  number  towards  the  lower 
part  of  the  ileum.  If  a  group  be  examined  by  dissecting  away  the 
muscular  coat,  you  find  that  it  is  composed  of  a  number  of  small 
oval  vesicles,  like  Florence  flasks,  embedded  in  the  sub-mucous 
tissue.  They  are  composed  of  masses  of  lymphoid  tissue,  of  about 
three-fourths  of  a  line  in  diameter,  and  contain  an  opaque  greyish 
fluid.  No  excretory  ducts  have  been  traced  from  these  vesicles, 
but  they  are  supposed  to  discharge  their  contents  by  rupture  of 

*  A  satisfactory  examination  of  the  intestinal  glands  can  be  made  only  in  speci- 
mens quite  recent,  taken  from  young  persons  who  have  died  suddenly,  or  from  a 
rapidly  fatal  disease. 

f  J.  N.  Lieberkiihn,  'Diss.  de  fabric,  etactione  villorum  intestin.  ten.,'  1782. 

\  J.  C.  Brunner,  '  Gland,  duoden.  seu  pancreas  secundarium,'  1715. 

§  Peyer,  '  De  glandulis  intestinorum,'  1682.  These  glands  were  first  described  by 
Nehemiah  Grew,  in  1681. 


STRUCTURE  OP  THE  LARGE  INTESTINE.          493 

their  capsules.  Between  the  vesicles  are  found  Lieberkiihn's 
follicles  ;  and  the  surface  of  the  patches  is  covered  with  villi. 
These  glands  are  liable  to  be  ulcerated  in  typhoid  fever.  They 
diminish  in  number  and  size  with  old  age. 

The  solitary  glands  are  scattered  over  all  parts  of  the  small 
and  large  intestines.  They  consist  of  the  same  lymphoid  structure 
as  the  glands  of  Peyer,  and  only  differ  from  them  in  being  solitary 
instead  of  being  aggregated  into  groups.  » 

The  lymphatics  consist  of  two  sets,  those  of  the  muscular 
and  those  of  the  mucous  coats;  the  latter  receive  those  from  the 
villi,  at  the  base  of  which  they  form  a  minute  plexus,  and,  after 
piercing  the  muscular  coat,  join  with  the  former,  which  are 
chiefly  found  between  the  longitudinal  and  the  circular  layers  of 
muscular  fibres. 

•  The  nerves  are  derived  from  the  superior  mesenteric  plexus, 
and  accompany  the  superior  mesenteric  artery  and  its  branches, 
between  the  layers  of  the  mesentery ;  after  reaching  the  intestinal 
walls  the  nerve-filaments  separate  from  the  arteries.  They  then 
pierce  the  external  longitudinal  muscular  fibres  and  form  a  very 
minute  gangliated  plexus,  Auerbach's  plexus  or  plexus  myen- 
tericus,  which  distributes  filaments  to  the  muscular  layer  of  the  en- 
tire intestinal  canal.  From  this  plexus  numerous  branches  perforate 
the  internal  circular  muscular  layer,  and  unite  to  form  a  largely 
gangliated  plexus,  Meissner's  plexus,  in  the  submucous  tissue. 
The  intermuscular  plexus  probably  supplies  the  muscular  coat  and 
regulates  the  peristaltic  action  of  the  bowel ;  the  submucous 
plexus  determines  the  calibre  of  the  blood-vessels. 

LABGE  The  principal  external  characters  of  the  large 

INTESTINE.  intestine  are  that  it  is  pouched  or  sacculated,  and 

that  it  has  attached  to  it  little  pendulous  portions  of  fat  covered 
by  peritoneum,  called  appendices  epiploicce.  The  pouches  (sac- 
culi)  are  produced  by  a  shortening  of  the  longitudinal  muscular 
fibres,  and  by  their  being  collected  into  three  bands,  about  half  an 
inch  wide,  nearly  equidistant  from  each  other.  One  of  these  bands 
corresponds  with  the  attached  part  of  the  circumference  of  the 
bowel;  another  with  the  front  part;  a  third  with  its  concavity.  If 


494         STEUCTUKE  OF  THE  LAEGE  INTESTINE. 

at  any.  given  part  the  three  bands  be  divided,  the  pouches  imme- 
diately disappear. 

In  a  colon  moderately  distended  and  dried,  we  observe  that  the 
mucous  membrane  forms  numerous  ridges  or  incomplete  septa 
(see  fig.  113):  they  correspond  to  the  grooves  on  the  external 
surface  of  the  bowel,  and  disappear,  like  the  sacculi,  when  the 
longitudinal  bands  are  divided. 

The  rectum  differs  from  the  rest  of  the  large  intestine  in  that 
its  longitudinal  muscular  fibres  are  not  collected  into  bands,  but 

FIG.  113. 


1.  Ileum. 

2.  Caecum  or  caput  coli. 


SECTION    THROUGH    THE    JUNCTION    OF   THE   LARGE    AND    SMALL     INTESTINE,    TO   SHOW 
THE    ILIO-C.SCAL    VALVE. 

distributed  equally  over  its  whole  circumference.  Moreover,  both 
the  longitudinal  and  circular  fibres  are  of  considerable  strength, 
like  those  of  the  oesophagus,  as  one  might  expect  from  the  parti- 
cular functions  which  these  parts  of  the  alimentary  canal  have  to 
perform.  For  an  inch  and  a  half,  or  thereabouts,  above  the  anus, 
the  circular  fibres  are  remarkably  developed,  and  constitute  the 
internal  sphincter  ani, 

The  mucous  membrane  of  the  large  intestine  differs  consider- 
ably from  that  of  the  small.     There  are  neither  valvulae  conni- 


8TEUCTUBE  OP  THE  LABGE  INTESTINE.          495 

ventes  nor  villi ;  but  the  glands  of  Lieberkiihn  and  the  lymphoid 
follicles  may  be  seen  studding  the  mucous  membrane.  The 
follicles  are  more  abundant  in  the  caecum  and  in  the  appendix 
vermiformis  than  in  any  other  part  of  the  alimentary  canal.  The 
blood-vessels  present  the  same  hexagonal  arrangement  on  the  sur- 
face as  that  of  the  stomach.  That  the  mucous  membrane  of  the 
large  intestine  may  be  temporarily  used  as  a  substitute  for  the 
stomach  is  proved  by  the  fact  of  persons  having  been  nourished 
for  many  weeks  solely  by  injections.  The  mucous  membrane  is 
lined  throughout  with  columnar  epithelium. 

ILIO-CJECAL  At  the  junction  of  the  small  with  the   large 

VALVB.  intestine  the  mucous  membrane  is  folded  so  as  to 

form  a  valve :  but  it  is  not  a  perfect  one,  as  is  proved  by  pouring 
water  into  the  large  intestine,  or  by  the  occasional  vomiting  of 
injections.  The  arrangement  of  the  valve  is  best  examined  in  a 
dried  preparation.  The  opening  is  a  transverse  fissure  like  a 
button-hole ;  and  the  two  flaps  are  arranged  like  an  upper  and  a 
lower  eyelid.  The  upper  lid  of  the  valve  projects  more  than  the 
lower,  so  that  the  contents  of  the  ileum  drop  naturally  down  into 
the  caput  coli,  where  they  are  apt  to  collect  and  form  hard  lumps. 
The  flaps  of  the  valve  consist  of  mucous  membrane  and  the  cir- 
cular fibres  of  the  ileum.  The  longitudinal  fibres  of  the  ileum 
are  continued  directly  on  to  the  caecum :  if  these  be  divided,  the 
ileum  can  be  drawn  out,  and  the  valve  disappears.* 

FOLDS  i»  THE  In  many  subjects  we  observe  that  transverse  or 

RECTUM.  oblique  folds  of  the   mucous   membrane  project 

into  the  rectum.  These  cannot  be  seen  to  advantage  unless  the 
bowel  be  hardened  by  alcohol  in  its  natural  position.  Three, 
more  prominent  than  the  rest,  and  half  an  inch,  or  thereabouts, 
in  width,  were  first  pointed  out  by  Mr.  Houston.-f-  One  projects 
from  the  upper  part  of  the  rectum,  opposite  the  prostate  gland ; 
another  is  situated  higher  up,  on  the  side  of  the  bowel;  while 
the  third  is  still  higher.  When  thickened  or  ulcerated,  these  folds 
are  apt  te  occasion  great  pain  and  obstruction  in  defaecation. 

*  It  is  interesting  to  note  that  the  surface  of  the  valve,  towards  the  ileum, 
covered  with  villi ;  not  so  the  surface  towards  the  large  intestine. 

t  'Dubli»  Hospital  Reports,'  yol.  T. 


496 


DISSECTION  OF  .THE  LOWER  EXTREMITY. 

THE  body  having  been  placed  on  its  back,  the  thigh  should 
be  slightly  flexed  and  abducted.  An  incision  should  be  made 
along  the  groin,  from  the  anterior  superior  spine  of  the  ilium  to 
the  spine  of  the  pubes ;  another,  from  the  middle  of  the  first, 
down  the  thigh  for  about  six  inches.  The  skin  being  reflected, 
the  superficial  fascia  and  vessels  will  be  exposed. 

SUPERFICIAL  This  fascia    varies    in  thickness,    according  to 

FASCIA.  the  condition  of  the  body.     Like  other  superficial 

fasciae,  it  is -divisible  into  two  layers,  between  which  are  situated 
the  inguinal  glands,  and  the  cutaneous  vessels.  The  upper  layer 
is  continuous  with  that  of  the  abdomen ;  the  deeper  layer  is  best 
marked  in  the  upper  part  of  the  thigh,  especially  where  it 
stretches  across  the  saphenous  opening  to  form  the  cribriform 
fascia,  and  is  attached  to  Poupart's  ligament. 

The  cutaneous  vessels  come  from  the  femoral  artery  and  are 
three  in  number,  the  superficial  epigastric,  the  su,perficial  ex- 
ternal pudic,  and  the  superficial  circumflexa  ilii  arteries  :  the  first 
ascends  over  Poupart's  ligament  to  the  abdomen  (p.  355) ;  the  second 
crosses  inwards  towards  the  pubes  ;  and  the  third  passes  outwards 
to  the  ilium.  Each  artery  is  accompanied  by  one,  sometimes 
by  two  veins,  which  empty  themselves,  either  directly  into  the 
femoral,  or  into  the  great  cutaneous  vein  of  the  thigh,  called  the 
saphena. 

SupEBFidAL  These   g^nds    are   easily   recognised,  by  their 

INGUINAL  oval  form  and  reddish-brown  colour.     There  are 

GLANDS.  two  sets :  one  set  runs  parallel  to  Poupart's  liga- 

ment, and  receives  the  lymphatics  from  the  penis,  the  scrotum, 
the  perineum,  the  anus,  the  buttock,  the  lower  part  of  the  ab- 


SUPERFICIAL    VESSELS    OF    THE    GROIN.  497 

dominal  wall,  and  the  upper  and  outer  aspect  of  the  thigh ;  the 
other  set  lies  along  the  saphena  vein,  and  receives  the  lymphatics 
from  the  foot,  the  leg,  and  the  lower  part  of  the  thigh.  This 
explains  why  in  cancer  of  the  scrotum  and  syphilitic  disease  of 
the  penis  the  first  set  becomes  enlarged  ;  and  the  second,  in  dis- 
eases of  the  lower  extremity.  The  lymphatic  vessels  which  pass 
to  and  from  the  glands  are  small,  and  may  escape  observation, 
unless  specially  looked  for.  They  all  pass  through  the  femoral 
ring  into  the  abdomen,  and  eventually  empty  themselves  into  the 
receptaculum  chyli. 

The  glands  mentioned  in  the  preceding  paragraph  are  all 
superficial.  There  are  others,  more  deeply  seated,  close  to  the 
great  vessels  of  the  thigh  :  these  are  much  smaller,  and  sometimes 
cannot  be  found. 

SUPERFICIAL  ^he  superficial  epigastric  artery  comes  through 

ARTERIES  OF  the   fascia   lata,   half   an  inch   below   Poupart's 

THE  GROIN.  ligament,  supplies  the  inguinal  glands,  and  anas- 

.tomoses  with  the  deep  epigastric  artery.  Its  further  course  is 
described  at  p.  355. 

The  superficial  circumfiexa  ilii  runs  parallel  to  Poupart's' 
ligament  towards  the  crest  of  the  ilium,  and  ends  in  the  skin  and 
subcutaneous  tissue. 

The  superficial  external  pudic  comes  through  the  saphenous 
opening,  crosses  over  the  spermatic  cord,  and  supplies  the  penis 
and  scrotum  in  the  male,  and  the  labium  in  the  female.  This 
artery  is  liable  to  be  divided  in  the  operation  for  femoral  hernia  ; 
also  in  that  for  phimosis,  since  it  runs  along  the  penis  to  supply 
the  prepuce.  Arising  directly  from  so  large  an  artery  as  the 
femoral,  it  sometimes  bleeds  profusely ;  for  it  is  an  admitted 
fact  that  when  even  a  small  branch,  coming  directly  from  a 
principal  artery,  is  divided  near  its  origin,  it  will  sometimes  pour 
out  as  much  blood  as  if  an  opening  were  punched  out  of  the 
trunk  as  large  as  the  area  of  the  divided  branch.*  There  is 
another  pudic  artery,  called  the  deep  or  inferior  external  pudic  : 

*  Mr.  Listen  had  occasion  to  tie  the  external  iliac  artery  for  a  supposed  injury  (by 
a  pistol-ball)  to  the  femoral.     It  was  discovered,  after  the  deatfi  of  the  patient,  that 

K  K 


498 


SUPERFICIAL   VESSELS    OF   THE    GROIN. 


this  runs  between  the  fascia  lata  and  the  pectineus,  supplying 
that  muscle,  the  scrotum  in  the  male,  and  the  labium  in  the  female. 
The  incision  should  be  prolonged  down  the  thigh,  over  the 
knee  to  the  tubercle  of  the  tibia.  The  skin  must  then  be  re- 
flected, to  expose  the  subcutaneous  tissue  over  the  whole  of  the 


FIG.  114. 


SUPERFICIAL    VESSELS   AND    GLANDS   OF    THE    GROIN.       SAPHENOUS    OPENING    WITH    THE 
CBIBRIFORM    FASCIA. 


1\  Saphenous  opening  of  the  fascia  lata. 

2.  Saphena  vein. 

3.  Superficial  epigastric  artery. 

4.  Superficial  circumflexa  ilii  artery. 


5.  Superficial  pudic  artery. 

6.  External  abdominal  ring. 

7.  Fascia  lata  of  the  thigh. 


front  of  the  thigh.      In  it  will  be  found  the  cutaneous  vessels  and 
nerves,  which  must  be  carefully  dissected. 


the  ball  had  injured  onJy  one  of  the  superficial  branches  of  the  femoral,  about  an  inch 
from  its  origin.     See  his  paper  in  the  'Med.-Chir.  Trans.'  vol.  xxix.  1846. 


.**. 


CUTANEOUS  NERVES  AND  VEINS.  499 

This  is  the  chief  subcutaneous  vein  of  the  lower 
SAPHENA  VEIN.      ,.,,-,  .   .  ,,  .,        ,.  , , 

limb.     Its  roots,  arising  on  the  inner  side  of  the 

foot,  unite  into  a  single  trunk,  which  ascends  in  front  of  the  inner 
ankle,  along  the  inner  side  of  the  leg,  behind  the  knee,  along  the 
inner  and  front  part  of  the  thigh,  where  it  passes  through  an  open- 
ing— the  saphenous  opening—  in  the  fascia  lata,  to  join  the  femoral 
vein,  immediately  below  the  crural  arch  (fig.  114).  In  this  long 
course  it  receives  several  tributary  veins,  some  of  which  are  often 
large  ;  and,  just  before  its  termination,  it  is  joined  by  the  super- 
ficial veins  which  accompany  the  arteries  of  the  groin  already 
alluded  to  (p.  497).  Like  all  subcutaneous  veins,  it  is  provided  at 
intervals  with  valves,  chiefly  where  joined  by  other  veins,  to  sup- 
port the  column  of  the  blood. 

CUTANEOUS  The  distribution  of  the  cutaneous  nerves-  of  the* 

NEETES.  thigh  varies  considerably,    but    they  are-  al-ways 

found  more  abundantly  -  on  the  inner  than  on  the  outer  aspect 
of  the  thigh.  The  nerves  are  divided  into  external?  middle, 
and  internal.  All  directly  or  indirectly  proceed  from  the  lumbar 
plexus,  and,  perforating  the  fascia,  divide  in-  the  subcutaneous- 
tissue. 

a.  The  external  cutaneous  nerve- is  a  branch  of 'the  second 
lumbar  nerve.     It  enters  the-<  thigh  beneath-  Poupart's  ligament 
close  to  .the  anterior  superior  spine  of  the  iliiirh.     Here  it  divides 
into  two  branches,  an  anterior  and  a  posterior.     The  anterior 
branch  comes  through  the  fascia  lata   about  four  inches  below 
Poupart's  ligament  and:  can  be  traced  down  the  outer  side  of  the 
thigh  as  far  as  the  knee,  giving  off  numerous  branches.      The 
posterior  branch,  after  coming  through  the  fascia,  divides  into 
filaments,  which  are  distributed  to  the  skin,  over  the  nates  and  the 
posterior  part  of  the-thigh.  : 

b.  The  middle  cutaneous  nerves,  one  or  two  in  number,  are 
given  off  by  the  anterior  crural.     They  pass  through  the  sartorius 
about  four  inches  below  Poupart's  ligament,  -  perforate  the  fascia 
lata,  and  descend  along  the  front  and  inner  part  of  the  thigh  as 
far  as  the  knee,  distributing  branches  on  either  side  ;  some  of 
which  communicate  with  the  long  .saphenous  nerve.     In  its  course 

K   K   2 


500  FASCIA    LATA. 

along  the  front  of  the  thigh  it  joins  with  the  crural  branch  of  the 
genito  crural  and  the  internal  cutaneous  nerves. 

c.  The  internal  cutaneous  nerve,  also  a  branch  of  the  anterior 
crural,  crosses  obliquely  over  the  femoral  artery.     It  then  divides 
into  branches  which  perforate  the  fascia  Ma,  and  supply  the  skin 
on  the  inner  side  of  the  thigh,  over  the  patella,  and  the  inner  side 
of  the  leg.  Some-  of  these  communicate  with  the  middle  cutaneous, 
the  long  saphenous  and  the  cutaneous  branch  of  the  obturator.* 

d.  The  crural  branch  of  the  genito-crural  nerve  perforates  the 
fascia  external  to  the  femoral  artery,  immediately  below  Poupart's 
ligament,  and  supplies  the  skin  in  front  of  the  thigh.     About  two 
or  three  inches  below  the  crural  arch  it  usually  communicates  with 
the  middle  cutaneous  nerve.  '  It  'also  distributes  a  few  filaments 
to  the  femoral  artery  in  its  passage  under  the  crural  arch. 

e.  The  ilio-inguinal  nerve,  after  emerging  from  the  external 
abdominal  ring,  supplies  the  skin  on  the  inner  aspect  of  the  thigh. 

Remove  the  subcutaneous  fat  to  examine  the 
I1  AS  CIA  LATA. 

fascia  lata  of  the  thigh.  The  use  of  this  fascia  is  to 
cover  the  muscles  of-  the  thigh  collectively,  and  to  form  separate 
sheaths  for  each ;  so  that; -it  not  only  keeps  them  together,  but 
maintains  each  in  its  proper  position.  A  knowledge  of  these 
sheaths  is  important,  because  they  interfere  with  the  progress  of 
deep-seated  matter  towards  the  surface,  and  cause  it  to  burrow  in 
this  or  that  direction  according  to  the  part  in  which  it  forms. 

The  fascia  is  not  of  equal  strength  all  round  the  thigh.  It  is 
comparatively  thin  on  the  inner  side ;  exceedingly  thick  and  strong 
down  the  outer  side  ;  here,  indeed,  it  has  the  appearance  of  a  dense 
expanded  aponeurosis,  strapping  down  the  vastus  externus  muscle  ; 
and  it  certainly  performs  the  office  of  a  tendon,  for  it  gives  inser- 
tion to  two  powerful  muscles — namely,  the  tensor  fasciae  femoris, 
and  the  gluteus  maximus  (fig.  115). 

The  fascia  lata  is  attached  to  the  margin  of  the  bones  whicli 
constitute  the  framework  of  the  lower  extremity.  Beginning  from 

*  It  is  important  to  note  that  one,  or  sometimes  two,  of  these  internal  cutaneous 
nerves  cross  the  sheath  of- the  femoral  arterj  just  where  thesartorius  begins  to  over- 
lap it ;  and  therefore  at  the  spot  where  it  is  usually  tied.  See  diag.,  p.  511. 


SAPHENOUS    OPENING. 


501 


FIG.  115. 


above,  its  attachment  can  be  traced  from  the  posterior  surface  of 
the  sacrum  and  coccyx,  along  the  crest  of  the  ilium,  thence  along 
the  crural  arch  to  the  body  of  the  pubes,  and  down  the  rami  of  the 
pubes  and  ischium.  Proceeding  down  the  thigh,  it  penetrates,  on 
either  side  of  the  limb,  to  the  linea  aspera,  forming  what  are  called 
the  external  and  internal  intermuscular  septa, 
which  separate  the  extensor  from  the  flexor 
muscles.  Below,  it  can  be  traced  round  the 
knee-joint,  and  is  particularly  strong,  especially 
on  the  outer  side,  where  it  is  attached  to  the 
head  of  the  tibia  and  fibula,  and  forms  the  inser- 
tion of  the  tensor  fascia?  femoris. 

There  are  numerous  small ,  apertures  in  the 
fascia,  through' which  the  cutaneous  nerves  and 
vessels  are  transmitted  ;  but  the  most  important 
one  is  the  large  opening — the  saphenous  opening 
— through  which  the  saphena  vein  passes  to  join 
the  femoral.  That  part  of  the  fascia  lata  situated 
external  to  the  saphenous  .opening  is  termed  the 
iliac  portion  of  the  fascia  lata ;  that  internal  to 
it,  the  pubic  portion. 

SAPHENOUS  The  saphenous  opening  is  an 

OPENING  IN  THE       oval  aperture  in  the  fascia  lata, 
FASCIA  LATA.  immediately  below    the    crural 

arch,  on  the  inner  side  of  .the  front  of  the  thigh, 
through  which  the  saphena  vein  passes  to  join 
the  femoral.  There  is  no  definite  border  to  the 
saphenous  opening  until  the  fascia,-  which  covers  FASCIA  ON  THE  OUT- 
the  opening  and  blends  with  its  margin,  has  been  SIDB  °F  T«E  THIGH. 
removed.  The  term  cribriform  has  been  given  i.  Tensor  fasciae  femoris. 

.  ..  111         2-  Glutens  maximus. 

to  this  tascia,  because  it  is  perforated  with  holes  3.  Lower  fibres  of  ditto. 

4.  Fascia  lata. 

tor   the   passage    of  the  superficial  vessels  and 
lymphatics.     It  is  a  thin  covering  over  the  saphenous  opening,  and 
is  prolonged  from  the  outer  edge  of  the  opening  over  the  sheath 
CRIBRIFORM          of  the  femoral  vessels,  and  adheres  on  the  inner 
FASCIA.  sj(je  to  the  fascia  .lata,  over  the  pectineus  muscle. 


502 


SAPHENOUS    OPENING. 


Some  anatomists  describe  this  fascia  as  a  portion  of  the  superficial 
fascia  ;  others  consider  it  as  a  thin  prolongation  of  the  fascia  lata 
itself  across  the  opening.  Its  chief  surgical  importance  is  de- 
rived from  the  fact  that  it  forms  one  of  the  coverings  of  a  femoral 
hernia. 

The  cribriform  fascia  must  now  be  removed  so  as  to  display 
the  saphenous  opening,  which  mil  appear  as  represented  in 
fig.  116. 

Keverting  to  the  saphenous  opening,  we  observe  that  it  is 
situated  just  below  the  crural  arch,  not  far  from  the  pubes  ;  that 
it  is  oval  with  the  long  axis  vertical,  and  about  one  inch  and  a  half 


1.  Crural  arch. 

Saphenous  opening  of 
the  fascia  lata. 

Saphena  vein. 
4.  Femoral  *ein. 


5.  Gimbernat's  ligament. 

6.  External       abdominal 

ring. 

7.  Position  of  the  internal 

ring   in  dotted   out- 
line. 


DIAGRAM   OF    THE    FEMORAL    RING    AN»   THE    SAPHENOUS    OPKNING. 

(The  arrow  is  introduced  into  the  femoral  ring.) 

long  and  an  inch  broad.  Its  border  on  the  inner  side  is  not  de- 
fined ;  for  here  the  fascia  lata  ascends  under  the  femoral  vessels, 
rand  is  continuous  with  the  iliac  fascia  of  the  pelvis.*  But  the 
outer  or  iliac  border  is  clearly  defined.  This  lies  in  front  of  the 
femoral  vessels,  is  crescent-shaped,  with  the  concavity  towards  the 
pubes,  and  called  the  falciform  process  of  Burns.  The  lower 
horn  of  the  crescent  curves  under  the  saphena  vein  with  a  well- 
defined  border,  and  on  being  traced  upwards  becomes  less  well 

*  On  the  inner  side  of  the  femoral  .vessels  the  pubic  portion  of  the  fascia  is  at- 
.tached  to  the  linea  ilio-pectinea. 


PARTS  CONCERNED  IN  FEMORAL  HERNIA.         503 

marked  until  it  is  gradually  lost  in  the  fascia  on  the  inner  side  of 
the  opening.  The  upper  horn,  Hey's  ligament,*  arches  over  the 
femoral  vein,  and  then  descending  slightly  is  continued  uninter- 
ruptedly into  Gimbernat's  ligament — Le.  into  that  part  of  the  crural 
arch  which  is  inserted  into  the  lineailio-pectinea.  The  upper  horn 
deserves  especial  attention,  because  it  forms  the  upper  boundary 
of  the  aperture  through  which  a  femoral  hernia  takes  place  ;  and, 
being  chiefly  concerned  in  the  constriction  of  the  rupture,  must 
be  divided  for  its  relief.  This  may  be  easily  ascertained  by  intro- 
ducing the  little  ringer  under  the  crural  arch,  on  the  inner  side  of  the 
femoral  vein — in  other  words,  into  the  femoral  ring  (see  the  arrow 
in  the  diagram). .  Feel  how  the  upper  horn  of  the  crescent  would 
girt"  the  neck  of  a  hernia,  and  that  its  tension  is  greatly  influenced 
by  the  position  of  the  limb  ;  for  if  the  thigh  be  bent  and  brought 
over  to  the  other  side,  the  tension  of  all  the  parts  is  materially 
lessened. f 

ANATOMY   OF    THE   PARTS   CONCERNED   IN   FEMORAL   HERNIA. 

The  anatomy  of  the  parts  concerned  in  femoral  hernia  cannot 
be  thoroughly  understood  without  the  assistance  of  special  dis- 
sections. The  following  demonstration,  therefore,  takes  for  granted 
that  the  student  has  the  opportunity  of  seeing  the  parts,  not' only 
on  their  femoral,  but  also  on  their  abdominal  side. 

The  different  parts  of  the  subject  should  be  examined  in  the 
following  order : — 

a.  The  formation  of  the  crural  arch. 

b.  The  arrangement  of  the  parts  as  they  pass  under  the  arch. 

c.  The  sheath  of  the  femoral  vessels. 

*  This  upper  horn  is  sometimes  called  '  Hey's  ligament,'  after  the  surgeon  who 
first  drew  attention  to  it:  'Observations  in  Surgery,' by  W.  Hey,  F.R.S.  London, 
1810. 

f  We  must  always  bear  in  mind  that,  though  the  crural  arch  and  the  fascia  at- 
tached to  it  have  received  particular  names,  they  are  not,  on  that  account,  distinct  and 
separate  ;  but  all  are  intimately  connected,  and  portions  merely  of  one  continuous  ex- 
pansion. Thus  all  the  parts  are  kept  in  a  condition  of  mutual  tension,  which  depends 
very  much  on  the  position  of  the  thigh. 


50  l<  PARTS    CONCERNED    IN    FEMORAL    HERNIA. 

d.  The  crural  canal  and  ring. 

e.  The  practical  application  of  the  subject. 

POUPART'S  The    lower   border   of  the   aponeurosis   of  the 

LIGAMENT  OB  external  oblique  muscle  extends  from  the  anterior 

CRURAL  ARCH.  superior  spine  of  the  ilium  to  the  spine  of  the 
pubes,  and  forms,  over  the  bony  excavation  beneath,  the  crural 
arch  or  Pouparfs  ligament.  (It  is  marked  by  the  dark  line  in 
Sg.  116.)  The  direction  of  the  arch  is  at  first  somewhat  oblique, 
but  towards  its  inner  half,  becomes  nearly  horizontal.  In  conse- 
quence of  its  intimate  connection  with  the  muscular  fascia  of  the 
thigh,  the  line  of  the  arch  describes  a  gentle  curve  with  the  con- 
vexity downwards.  The  arch  is  attached  to  the  spine  of  the  pubes, 
and  also  for  some  distance  along  the  linea  ilio-pectinea  (fig.  116). 
This  additional  attachment,  called  Gimbernatfs  ligament,*  is  of 
importance,  for  it  is  frequently  the  seat  of  stricture  in  femoral 
hernia. 

GIMBERNAT'S  The  best  view  of  Gimbernat's  ligament  is  ob- 

LIOAMENT.  tained   from  within  the  abdomen ;    it  being  only 

necessary  to  remove  the  peritoneum.  It  is  placed  nearly  horizon- 
tally, in  the  erect  posture,  and  is  triangular  with  its  apex  at  the 
pubes  and  its  base  directed  outwards.  In  front,  it  is  continuous 
with  the  crural  arch ;  behind,  it  is  inserted  into  the  linea  ilio- 
pectinea  ;  externally,  it  is  continuous  with  the  fascia  lata  through 
Hej's  ligament  (fig.  116).  Its  length  is  from  f  of  an  inch  to  1 
inch ;  but  it  is  usually  longer  in  the  male  than  the  female. 

On  putting  your  finger  into  the  femoral  ring,  you  feel  the 
sharp  and  wiry  edge  of  this  ligament :  observe,  too,  that  as  the 
body  lies  on  the  table,  the  plane  of  the  ligament  is  perpendicular, 
and  therefore  that  it  recedes  from  the  surface. 

ARRANGEMENT           The  crural  arch  transmits  from  the  abdomen  into 

OF  THE  PARTS           the  thigh    (proceeding  in  order  from  the  outer 

WHICH  PASS  UNDER     side)  the  following  objects,  shown  in  fig.  117): 

1.  The  external  cutaneous  nerve;  2.  The  iliacus 

and  psoas  muscles,  with  the  anterior  crural  nerve   between  them ; 

"*  Don  Antonio  de  Gimbernat  was  a  Spanish  surgeon,  who  published,  in  1793,  '  A 
new  Method  of  Operating  for  the  Femoral  Hernia.'     Madrid. 


PARTS  CONCERNED  IN  FEMORAL  HERNIA. 


505 


3.  The  femoral  artery  and  vein  with  the  crural  branch  of  the 
genito-crural  nerve.  These  muscles  and  vessels  fill  up  the  space 
beneath  the  crural  arch,  except  on  the  inner  side  of  the  femoral 
vein,  where  a  space  is  left  for  the  passage  of  the  lymphatics  :  this 
is  called  the  crural  or  femoral  ring.  The  muscles  are  separated 
from  the  vessels  by  a  strong  vertical  fibrous  partition  passing  from 
the  arch  to  the  bone,  which  is  nothing  more  than  a  continuation 
of  the  sheath  of  the  psoas.  The  artery,  too,  is  separated  from  the 
vein  by  a  similar,. although  a  much  weaker  partition,  and  there  is 

FIG.  117. 


External  cutaneous  n. . 


Iliacus 

Anterior  crural  n.    .     .     . 


Crural  arch. 
—  -   External  ring. 


r    Femoral  ring. 

Femoral  vein  and  artery. 


POSITION    OF    PARTS    UNDER    THE    CRURAL   ARCH    (VERTICAL   SECTIOS). 

a  third  close  to  the  inner  side  of  the  vein.  These  three  partitions 
not  only  keep  all  the  parts  in  their  right  place,  but  confine  the 
arch  down  to  the  bone,  and  prevent  its  being  uplifted  by  any  pro- 
trusion between  it  and  the  muscles  and  vessels.  This,  coupled 
with  the  close  attachment  of  the  fascia  iliaca  to  the  crural  arch, 
explains  why  a  femoral  hernia*  rarely  takes  place  in  any  other 
situation  than  on  the  inner  side  of  the  femoral  vein.* 

*  If  the  partitions  from  any  cause  yield,  on-become  slock,  then  a  rupture  may  de- 
si-end  in  front  of  the  vessels,  or  oven  (though  this  is  rare)  on  the  outer  side  of  the 
artery. 


506 


PARTS    CONCERNED    IN    FEMORAL    HERNIA. 


SHEATH  OF  THE  The  femoral  vessels  descend  beneath  the  crural 
FEMORAL  VESSELS,  arch,  enclosed  in  a  funnel-shaped  membranous 
sheath.  This  sheath  appears  to  be  derived  immediately  from  the 
arch  itself,  but  it,  is  really  formed,  in  front,  by  a  prolongation 
from  the  fascia  transversalis  of  the  abdomen.  This  prolongation, 
uniting  with  the  continuation  from  the  fascia  iliaca  to  join  the 
fascia  lata  behind  the  femoral  vessels,  forms  a  funnel,  with  the 
wide  part  uppermost,  into  which  the  femoral  vessels  enter.  This 
is  the  funnel-shaped  sheath  of  the  femoral  vessels. 

FIG.  118. 


1, 1.  Fascia  transver- 
salis. 

2.  Internal  ring. 

3.  Crural  arch  re- 

flee  ted. 


4.  Sheath  of  the 

moral  vessels. 

5.  Saphena  vein. 


DIAGRAM    OF   THE    SHEATH    OF    THE    FEMORAL    VESSELS. 

To  examine  this  sheath  satisfactorily,  it  is  necessary  to  reflect, 
from  its  attachment  to  the  crural  arch,  the  upper  horn  of  the 
saphenous  opening,  as  shown  in  fig«  118.  By  this  proceeding, 
we  expose  the  fascia  transversalis  descending  over  the  femoral 
vessels,  and  forming  the  front  part  of  their  sheath.  The  hind 
part  of  the  sheath  is  formed  by  the  fascia  iliaca,  which  runs  down 
behind  the  vessels  to  join  the  pubic  portion  of  the  fascia  lata. 
The  sheath  descends  as  low  as  the  lower  horn  of  the  saphenous 
opening,  where  it  is  gradually  lost  upon  .the  ordinary  fibrous 
investment  of  the  femoral  vessels.  The  outer  part  of  the  sheath 


PARTS    CONCERNED    IN    FEMORAL    HERNIA.  507 

is  perforated  by  the  crural  branch  of  the  genito-crural  nerve,  and 
the  superficial  arteries  of  the  groin ;  the  inner  part,  by  the 
saphena  vein  and  some  lymphatic  vessels. 

The  sheath  of  the  femoral  vessels  is  divided  into  three  com- 
partments separated  from  each  other  by  partitions :  the  outer 
is  occupied  by  the  femoral  artery ;  the  middle,  by  the  femoral 
vein  ;  the  inner  is  the  crural  canal,  into  which  the  femoral  hernia 
descends. 

Practically,  the  sheath  is  important  for  many  reasons  : — 

1.  A  femoral  hernia  descends  within  it.  2.  It  constitutes, 
therefore,  one  of  the  coverings,  fascia  propria,  of  the  hernia. 
3.  It  contains  in  its  substance  bands  of  fibres,  deep  crural  arch, 
running  in  the  same  direction  as  the  crural  arch,  but  quite  inde- 
pendent of  it,  as  shown  in  fig.  118;  these  bands  lie  over  the  neck 
of  the  sac,  and  are  often  the  seat  of  the  stricture  ;  it  is  therefore 
necessary  to  divide  them  before  the  intestine  can  be  returned. 

CRURAL  CANAL  The  hollow  under  the  crural  arch  is  completely 

AND  FEMORAL  occupied  by  the  structures  before  mentioned,  ex- 
RlNG-  cept  for  a  small  space,  called  the  crural  canal, 

on  the  inner  side  of  the  vein.  This  canal  is  from  a  quarter  to 
half  an  inch  in  length.  It  commences,  above,  in  the  femoral 
ring ;  and  ends,  below,  at  the  saphenous  opening.  The  femoral 
ring  is  the  upper  opening  of  the  crural  canal,  and  is  bounded, 
in  front,  by  the  crural  arch;  behind,  by  the  bone;  on  the  outer 
side,  by  the  femoral  vein  ;  on  the  inner  side,  by  the  thin,  wiry 
edge  of  Grimbernat's  ligament.  In  the  undisturbed  condition  of 
the  parts  there  is  no  gap ;  it  is  only  a  weak  place,  which,  when 
a  hernia  escapes  through  it,  feels  like  a  ring :  hence  the  name  of 
femoral  nng.* 

The  femoral  ring  is  surrounded  on  all  sides  by  unyielding 
structures.  This  accounts  for  the  little  benefit  afforded  by  the 
warm  bath  in  cases  of  strangulation.  Sir  W.  Lawrence  was  in 

*  The  femoral  ring  is  naturally  occupied  by  a  little  fat  and  cellular  membrane,  by 
lymphatic  vessels,  and  often  by  a  small  lymphatic  gland,  But  we  have  never  met  with 
anything  deserving  the  name  of  a  '  diaphragm '  or  membranous  septum,  such  as  is 
described  by  Cloquetas  the  '  septum  crurale,'  and  is,  surgically,  of  no  importance. 


508  PARTS    CONCERNED    IN    FEMORAL    HERNIA. 

the  habit  of  saying  that  he  never  saw  a  strangulated  femoral 
hernia  where  the  warm  bath  was  of  any  avail. 

PRACTICAL  From  what  has  been  said,  the  student  ought 

APPLICATION  ov  now  to  understand — 1,  at  what  aperture  a  femoral 
THE  SUBJECT.  hernia  escapes  from  the  abdomen  ;  2,  the  course 

which  it  takes,  and  its  relations  to  the  surrounding  parts  ;  3,  the 
proper  mode  of  attempting  the  reduction ;  4,  the  structure  and 
arrangement  of  its  coverings ;  and,  lastly,  the  probable  seat  of 
stricture. 

The  hernia  escapes  from  the  abdomen  through  the  femoral 
ring — that  is,  under  the  weak  part  of  the  crural  arch,  between 
the  femoral  vein  and  Gimbernat's  ligament.  Here  is  the  mouth  of 
the  hernial  sac,  or  that  part  of  it  which  communicates  with  the 
abdomen.  It  descends  for  a  short  distance  nearly  perpendicu- 
larly, and  projects  as  a  small  tumour  in  front  of  the  pectineus 
muscle.  Its  progress  downwards,  however,  is  soon  arrested,  partly 
by  the  very  close  adhesion  of  the  subcutaneous  structures  to 
the  lower  margin  of  the  saphenous  opening ;  partly  by  the 
flexion  of  the  thigh.  Consequently,  if  the  hernia  increase  in 
size,  it  must  rise  over  the  crural  arch,  where  the  subcutaneous 
tissue  offers  less  resistance;  and  the  bulk  of  the  hernia  extends 
outwards  towards  the  ilium,  assuming  more  or  less  of  an  oblong 
form,  with  the  long  axis  parallel  to  the  crural  arch.  Since,  then, 
the  body  of  the  hernia  forms  a  very  acute  angle  with  the  neck, 
the  right  mode  of  attempting  its  reduction  is,  to  draw  it,  first, 
down  from  the  groin,  and  then  to  make  pressure  on  it,  backwards, 
in  the  direction  of  the  femoral  ring. 

COVERINGS  OF  The  coverings  of  a  femoral  hernia  are  as  fol- 

A  FEMORAL  lows  : — It    first    protrudes    before   it  the  perito- 

HERNIA.  neum,  technically  called  the  hernial  sac.*     The 

sac  is  covered  by  more  or  less  fat,  according  to  the  condition  of 
the  patient,  called  the  sub-peritoneal  fat.  It  next  pushes  before 
it  the  sheath  of  the  femoral  vessels,  which  forms  an  investment 

*  In  some  cases  the  fascia  propria  so  much  resembles  the  hernial  sac,  that  it  is  not 
easy  to  distinguish  between  them.  Generally  speaking  they  are  separated  by  a  small 
quantity  of  fat. 


TARTS    CONCERNED    IN    FEMORAL    HERNIA.  509 

called  the  fascia  propria.  In  front  of  this  is  the  cribriform 
fascia.  Lastly,  there  is  the  subcutaneous  tissue  and  skin. 

SEAT  OF  The  seat  of  stricture  is  usually  at  the  femoral 

STKICTURE.  ring?  and  the  position  of  the  neighbouring  blood- 

vessels indicates  that  the  proper  direction  in  which  to  divide  the 
stricture  is,  either  directly  inwards,  through  Grimbernat's  ligament, 
as  recommended  by  Sir  W.  Lawrence,  or  upwards  through  Key's 
ligament,  as  recommended  by  Sir  A.  Cooper.*  There  is  no  risk 
of  wounding  an  artery,  supposing  the  vessels  to  take  their  ordi- 
nary course.  But  it  occasionally  happens  (p.  441),  that  the  obtu- 
rator artery  runs  above  (in  the  recumbent  position)  the  femoral 
ring ;  in  such  a  case,  the  neck  of  the  sac  would  be  encircled  by 
a  large  blood-vessel. t  From  the  examination  of  two  hundred 
bodies,  the  chances  are  about  seventy  to  one  against  this  unfavour- 
able distribution.  But  the  possibility  of  it  has  given  rise  to  this 
rule  in  practice — not  to  cut  deeply  in  any  one  place  through 
the  stricture,  but  rather  to  notch  it  in  several.  By  this  proceeding 
we  are  much  less  likely  to  wound  the  abnormal  artery,  because  it 
does  not  run  at  the  base  of  Grimbernat's  ligament,  but  about  a 
line  and  a  half  from  the  margin  of  it.J 

Such  is  an  outline  of  the  anatomy  of  the  parts  concerned  in 
a  femoral  hernia.  The  normal  anatomy  in  each  case  being 
similar,  it  might  be  supposed  that  all  operations  for  the  relief 
of  this  kind  of  hernia  would  be  straightforward  and  pretty  much 
alike  ;  but  this  is  very  far  from  being  the  case  :  indeed,  surgeons 
agree  that  they  never  operate  without  the  expectation  of  meeting 
some  peculiarity. 

*  The  operation  recommended  by  Sir  A.  Cooper  is  that  usually  performed  now; 
because,  if  Gimbernat's  ligament  be  divided,  its -cut  edges  often  retract  to  such  an  ex- 
tent, that  no  truss  can  possibly  retain  the  hernia  when  the  patient  assumes  the  erect 
posture. 

f  The  museum  of  St.  Bartholomew's  Hospital  contains  two  examples  of  double 
femoral  herniae  in  the  male,  with  the  obturator  arising  on  each  side  from  the  epigas- 
tric. In  three  out  of  the  four  hernise  the  obturator  runs  on  the  inner  side  of  the 
mouth  of  the  sac.  See  Prep.  55,  69,  Series  17- 

{  During  the  session  of  1867-68  more  than  half  a  dozen  instances  occurred  where 
the  obturator  artery  was  given  off  by  a  common  origin  with  the  epigastric  artery.  In 


510  SCAEPA'S  TRIANGLE. 

The  fascia  must  now  be  removed  from  the  front 
of  the  thigh,  without  disturbing  the  subjacent 
muscles  from  their  relative  positions.  The  mass  of  muscles,  on 
the  inner  side  of  the  thigh,  consists  of  the  adductors  ;  that  in  the 
middle,  of  the  extensors  :  the  long  thin  muscle  crossing  obliquely 
in  front  from  the  outer  to  the  inner  side,  is  the  sartorius.  In  the 
middle  are  seen  the  femoral  vessels,  and  the  anterior  crural  nerve 
emerging  beneath  the  crural^  arch. 

This  muscle  arises  from  the  anterior  superior 
spine  of  the  ilium,  and  from  the  ridge  below  to 
the  extent  of  an  inch.  It  passes  obliquely  like  a  strap  over  the 
front  of  the  thigh  towards  the  inner  side;  and  then  descends 
almost  perpendicularly  on  the.  inner  side  of  the  thigh  as  far  as  the 
knee,  where  it  terminates  in  a  flat  tendon  which  expands,  and  is 
inserted  into  the  inner  and  front  part  of  the  tibia  just  below  its 
tubercle.  The  tendon, ,  appears  all  the  wider  on  account  of  its 
broad  connection  with  the  fascia  of  the  leg,  which  extends  as  low 
as  the  internal  malleolus.  The  broad  insertion  of  this  muscle 
lies  anterior  to  and  covers  the  tendinous  insertions  of  the  gracilis 
and  semi-tendinosus,  and  between  them  is  a  bursa.  A  large  bursa* 
is  interposed  between  the  tendon  and  the  internal  lateral  liga- 
ment. The  chief  action  of  the  muscle  is  to  fix  the  pelvis  steadily 
on  the  thigh.f  It  crosses  one  leg  over  the  other,  as  tailors  sit 
when  at  work.  Its  nerve  comes  from  ,tke  middle  cutaneous  branch 
of  the  anterior  cruraL 

SCAEPA'S  In  consequence  of  the  oblique  direction  of  the 

TBIANGLE.  upper  third  of  the  sartorius,  a  triangle  is  formed, 

which  has  this  muscle  and  the  adductor  longus  for  its  two  sides, 
and  the  crural  arch  for  its  base  t-the  triangle  is  called  Scarpa's.^ 

all  these  cases,  however,  the  artery  passed  close  by  the  bone,  that  is  behind  the  sac,  so 
that  it  -would  not  have  been  injured  in  the  operation  for  relief  of  strangulation. 

*  In  persons,  females  especially,  who  are  in  the  habit  of  riding,  this  bursa  some- 
times becomes  enlarged. 

f  Hence  the  name  given  to  it  bySp'rgelius(De  corporis  hum.  fabric.),  'Quern  ego 
sirtorium  museulum  vocare  soleo,  quod  sartores  eo  maxime  utuntur,  dum  crus  cruri 
inter  consuendum  imponunt.' 

{  So  called  in  compliment  to  the  Italian  anatomist  who  first  tied  the  femoral  in  it 
for  popliteal  aneurysm. 


SCARPA  8    TRIANGLE. 


511 


The  contents  of  this  important  space  should  be  carefully  dis- 
played, and  their  relative  positions  well  studied.  This  triangle 
contains  all  the  parts  which  pass  under  the  crural  arch  :  namely, 
from  without  inwards,  the  external  cutaneous  nerve,  close  to  the 
anterior  spine  of  the  ilium ;  the  iliacus  internus  and  psoas ;  the 
anterior  crural  nerve  and  its  divisions,  especially  the  long 
saphenous  nerve ;  the  common  femoral  artery  with  its  two  large 
divisions,  the  superficial  femoral  and  the  profunda,  which  run 


1.  Sartorius. 

2.  Adductor  longus. 

3.  External  cutaneous 

n. 

4.  Iliacus  int:-rnus. 

5.  Anterior  crural  n. 

6.  Femoral  artery. . 


7.  Femoral  vein. 

8.  Pectineus. 

9.  Long  saphenous  n. 

10.  Internal  cutaneous 
n. 

11.  Nerve  to  vastus  iu- 
ternus. 

12.  Middle  cutaneous  n. 


DIAGRAM    OF   SCARPA's    TRIANGLE. 

down  nearly  parallel  to  each  other,  the  latter  giving  off  the  in- 
ternal and  external  circumflex ;  the  femoral  vein,  joined  by  the 
profunda  vein  and  the  internal  saphena,  and  the  pectineus  muscle 
with  the  deep  external,  pudic  artery. 

The  triangle  is  important  in  a  surgical^  point  of  view,  since  it 
is  in  this  space  that  the  femoral  artery  is  usually  ligatured  for 
popliteal  aneiirysm.  Th 3  guide  "to  the  artery  is  the  inner  border 
of  the  sartorius.  'The  situation  at  which  this  muscle  crosses  over 


512  ADDUCTOR    MUSOTES. 

the  femoral  artery,  varies  from  one. and  a  half  to  four  and  a  half 
inches  below  Poupart's  ligament ;  so  that  no  rule  can  be  laid  down 
as  to  the  exact  situation  where  the  artery  disappears  beneath  the 
sartorius.  The  best  way  to  find  the  inner  border  of  the  muscle 
during  life,  is  to  make  the  patient  put  it  in  action. 

ADDUCTOH  A  strong  group  of  muscles,  called  the  adductors, 

MUSCLES.  extends  along  the  inner  side   of  the  thigh,   from 

the  pelvis  to  the  femur.  Their  two  most  important  actions  are 
to  co-operate  in  balancing  the  pelvis  steadily  on  the  thigh,  as  in 
standing  on  one  leg ;  and  (if  the  fixed  point  be  reversed)  to  draw 
together  or  adduct  the  thighs,  at  the  same  time  rotating  the 
thigh  externally.  They  are  five  in  -number,  and  are  supplied, 
with  one  exception — the  pectineus — by  the  same  nerve — namely, 
the  obturator.  They  are  -termed,  respectively,  the  gracilis,  ad- 
ductor longus,  pectineus,  adductor  l>revis,  and  adductor  magnus. 
The  innermost  is  the  gracilis  ;  to  clean  it  properly,  it  should  be 
stretched  by  separating  one  thigh  from  the  other. 

This  long,  flat  muscle  arises  by  a  broad,  ribbon- 
like  tendon  from  the  pubes  close  to  the  symphysis, 
and  from  the  border  of  the  pubic  arch  nearly  as  low  as  the  tuber 
ischii.  It  descends  almost  perpendicularly  on  the  inner  side  of  the 
thigh,  and  terminates  in  a  round  tendon  which  subsequently  spreads 
out,  and  is  inserted  into  the  inner  side  of  the  tibia  below  the 
tubercle,  immediately  behind  the  sartorius  and  above  the  semi- 
tendinous.  The  tendon  plays  over  the  internal  lateral  ligament 
of  the  knee-joint,  and  there  is  a  bursa  to  diminish  friction.  This 
muscle  assists  in  fixing  the  pelvis,  and  in  adducting  the  thigh  ;  it 
further  helps  to  bend  the  knee.  Its  nerve  comes  from  the  anterior 
division  of  the  obturator. 

ADDUCTOR  This  triangular  muscle  lies  between  the  gracilis, 

LONGUS.  and  the  pectineus,  and  arises  by  a  round  tendon 

from  the  front  of  the  body  of  the  pubes  below  the  crest.  As  it 
descends,  the  muscle  becomes  broader,  and  is  inserted  into  the 
middle  third  of  the  inner  margin  of  the  linea  aspera  of  the  femur. 
It  forms  with  the  sartorius  the  triangular  space  called  Scarpa's 
triangle,  above  described.  It  rests  upon  the  adductor  brevis  and 


ADDUCTOR    MUSCLES.  513 

magnus,  the  profunda  vessels  and  the  obturator  nerve.  It  is  sup- 
plied by  the  anterior  division  of  the  obturator  nerve. 

This  muscle  lies  on  the  same  plane,  but  external 
to  the  adductor  longus,  from  which  it  is  separated 
by  a  slight  interval,  in  which  may  be  seen  the  anterior  division  of 
the  obturator  nerve.  It  arises  from  the  triangular  surface  of  the 
pubes  in  front  of  the  linea  ilio-pectmea,  and  is  inserted  into  the 
upper  part  of  the  ridge  leading  from  the  lesser  trochanter  to  the 
linea  aspera.  It  lies  upon  the  adductor  brevis,  the  obturator 
vessels  and  nerve  and  the  obturator  externus.  Its  nerve  comes 
from  the  anterior  craral,  sometimes  also  from  the  obturator 
(p.  410). 

By  separating  the  contiguous  borders  of  the  pectineus  and  the 
adductor  longus,  the  adductor  brevis  is  exposed  with  the  anterior 
division  of  the  obturator  nerve  lying  upon  it.  To  obtain  a- com- 
plete view  of  it,  the  pectineus  and  adductor  longus  must  be 
reflected  from  their  origins.  The  obturator  nerve  supplies  all  the 
adductors.  It  leaves  the  pelvis  through  the  upper  part  of  the 
obturator  foramen,  and  soon  divides  into  an  anterior  and  posterior 
branch :  the  anterior  runs  in  front  'of  the  adductor  brevis,  and 
supplies  the  hip-joint,  the  adductor  longus,  the  gracilis,  and  some- 
times the  adductor  brevis  and  the  pectineus  ;  the  posterior  runs 
behind  the  adductor  brevis,  and  supplies  it  as  well  as  the  obturator 
externus,  the  adductor  magnus,  and  the  knee-joint. 

ADDUCTOR  This  muscle  arises  from  the  front  surface  of  the 

BBEVIS<  body  of  the  pubes  near  the  symphysis,  and  from 

its  descending  ramus  for  about  an  inch  ;  it  widens  as  it  descends, 
and  is  inserted  behind  the  pectineus  into  the  whole  length  of 
the  ridge  leading  from  the  lesser  trochanter  to  the  linea  aspera. 
Behind,  it  rests  upon  the  posterior  division  of  the  obturator  nerve, 
and  the  adductor  magnus.  Its  nerve  is  derived  from  the  obtu- 
rator. By  reflecting  it  from  its  origin,  the  following  muscle  is 
exposed.* 

*  Beneath  the  adductor  brevis,  and  running  parallel  with  the  upper- border  of  the 
adductor  magnus,  is  seen  the  obturator  externus.  But  the  description  of  this  muscle 
is  deferred  till  the  dissection  of  the  external  rotators  of  the  thigh. 

L  L 


514  ADDUCTOK   MUSCLES. 

ADDUCTOR  This  muscle  arises  from  the  lower  part  of  the 

MAGNUS.  body  of  the  pubes  near  the  symphysis,  from  the 

rami  of  the  pubes  and  ischium,  and  from  the  tuberosity  of 
the  ischium.  Its  fibres  spread  out,  and  are  inserted,  behind  the 
other  adductors,  into  the  lower  part  of  the  linea  quadrati,  into  the 
ridge  leading  from  the  great  trochanter  to  the  linea  aspera,  also 
into  the  whole  length  of  the  linea  aspera,  and  the  ridge  leading 
from  it  to  the  inner  condyle.  The  upper  fibres  pass  transversely 
outwards  to  their  insertion,  -while  the  lower  fibres  descend  nearly 
vertically.  In  front  of  the  muscle  are  the  adductor  longus  and 
brevis,  the  vastus  internus,  the  obturator  nerve  and  artery  and  the 
profunda  artery ;  above  it  are  the  internal  circumflex  artery,  the 
obturator  externus,  and  the  quadratus  femoris ;  behind  it,  the 
biceps,  semi-tendinous  and  semi-membranosus,  the  great  ischiatic 
nerve,  and  the  -gluteus  maximus.  Its  nerve  comes  from  the 
posterior  division  of  the  obturator.  Observe  that  all  the  adductor 
muscles  are  i  inserted  into  the  Jemur  by  flat  tendons  more  or  less 
connected. 

About  the  junction  of  the  upper  two-thirds  with  the  lower 
third  of  the  thigh,  the  femoral  artery  passes  through  an  oval,  open- 
ing in  the  tendon  of  the  adductor  magnus. 

PSOAS  MAGNUS  These  muscles  have  been  fully  described  in  the 

AND  ILIACUS  dissection  of  the  abdomen  (p.  398). 

INTERNUS.  i"-i 

TENSOR  FASCIA          This  muscle  is  situated  at  the  upper  and  outer 
FEMORIS.  part  of  the  thigh.     It  arises  from  the  external  lip 

of  the  crest  of  the  ilium,  close  to  the  anterior  superior  spine.  It 
descends  with  a  slight  inclination  backwards,  and  is  inserted,  at 
the  junction  of  the  upper  with  the  middle  third  of  the  thigh, 
between  two  layers  of  the  strong  aponeurosis,  generally  described 
as  part  of  the  fascia  lata*  (p.  500).  Its  chief  use  is  to  fix  the  pelvis 
steadily  on  the  thigh,  and  to  rotate  the  thigh  inwards ;  in  this  last 
action  it  co-operates  with  the  anterior  fibres  of  the  gluteus  medius, 
with  which  it  is  almost  inseparably  connected.  Anyone  may  con- 
vince himself, of  this  by  placing  his  hand  on  the  hip,  and  rotating 

*  The  deeper  of  these  two  layers  runs  up  to  be  strongly  connected  with  the  ten- 
don of  the  rectus  and  the  front  of  the  capsule  of  the  hip-joint. 


EXTENSOR    MUSCLES.  5J5 

the  thigh  inwards.     Both  these  muscles  are  supplied  by  the  same 
nerve — the  superior  gluteal. 

To  form  an  adequate  idea  of  the  strength,  extent,  and  connec- 
tions of  the  aponeurosis  on  the  outer  side  of  the  thigh,  it  should  be 
separated  from  the  vastus  externus  muscle  upon  which  it  lies. 
There  is  no  difficulty  in  doing  so,  for  it  is  united  to  the  muscle  by 
an  abundance  of  loose  connective  tissue.*  With  a  little  persever- 
ance the  aponeurosis  can  be  traced  to  the  linea  aspera,  the  head  of 
the  tibia,  and  the  fibula,  completely  protecting  the  outer  side  of 
the  knee-joint. 

EXTENSOR  The  powerful  muscles  occupying  the  front  of  the 

MUSCLES  OR  thigh,  and  situated  between  the  tensor  fasciae  on 

QUADRICEPS  the  outer  side  and   the  adductors  on  the  inner, 

are  extensors  of  the  leg.  One  of  them — the 
rectus — arises  from  the  pelvis  ;  the  other — the  triceps — arises 
from  the  shaft  of  the  thigh  bone  by  three  portions,  called,  re- 
spectively, the  crureus,  the  vastus  intemus  and  externus.  All  are 
supplied  by  the  anterior  crural  nerve. 

To  see  the  origins  of  the  rectus  femoris,  dissect  between  the 
origin  of  the  sartorius  and  the  tensor  fasciae  ;  in  doing  so,  avoid 
injuring  the  branches  of  the  external  circumflex  artery. 

EECTUS  This  muscle  arises  from  the  pelvis  by  two  strong 

FEMORIS.  tendons,  which  soon  unite  at  an  acute  angle  :  one 

— round — from  the  anterior  inferior  spine  of  the  ilium,  the  other 
— flat — from  the  rough  surface  of  the  ilium,  just  above  the  aceta- 
bulum.  The  muscle  descends  along  the  front  of  the  thigh,  and  is 
inserted  into  the  common  extensor  tendon,  which  will  be  pre- 
sently examined.  The  structure  of  this  muscle  is  remarkable.  A 
tendon  runs  down  the  centre,  and  the  muscular  fibres  are  inserted 
on  either  side  of  it,  like  the  vane  on  the  shaft  of  a  feather.  Its 
nerve  comes  from  the  anterior  crural. 

This  mass  of  muscle  invests  like  a  cloak  the 

TliTCE!PS  Ex~ 

TENSOR.  greater  part  of  the  front  and  sides  of  the  shaft  of 

the  femur;  therefore  the  whole  of  it  cannot  be 

*  When  this  tissue  becomes  the  seat  of  suppuration,  the  pus  is  apt  to  extend  all 
down  the  outside  of  the  thigh,  not  being  able  to  make  its  way  to  the  surface  by  reason 
of  the  dense  fascia. 

L   L   2 


516  EXTENSOR   MUSCLES. 

seen  without  completely  dissecting  the  thigh.  It  consists  of  an 
outer,  middle,  and  inner  portion,  called,  respectively,  the  vastus 
externus,  the  crureus,  and  the  vastus  internus.  The  vastus  ex- 
ternus arises  by  a  strong  aponeurosis  from  the  outer  side  of  the 
base  of  the  great  trochanter,  and  from  the  outer  lip  of  the  linea 
aspera  nearly  down  to  the  external  condyle.  The  crureus  and 
the  vastus  internus  arise  (conjointly)  from  the  upper  three- 
fourths  of  the  front  and  inner  surfaces  of  the  shaft  of  the  femur, 
and  from  the  entire  length  of  the  inner  lip  of  the  linea  aspera.  The 
ultimate  insertion  of  the  several  parts  of  the  triceps  is  (through 
the  patella)  into  the  common  extensor  tendon  of  the  knee. 

A  few  of  the  deeper  fibres  of  the  crureus  are  inserted  into  the 
fold  of  the  synovial  membrane  of  the  knee-joint  which  rises  above 
the  patella.  These  are  described  as  a  distinct  muscle,  under  the 
name  of  the  sub- crureus.  Their  use  is  to  raise  the  synovial 
membrane,  so  that  it  may  not  be  injured  by  the  play  of  the 
patella.  Since  the  triceps  is  connected  to  the  lower  part  of  the 
shaft  of  the  femur  only  by  loose  connective  tissue,  there  is  nothing 
to  prevent  the  distension  of  the  synovial  membrane,  in  cases 
of  inflammation,  to  the  extent  of  several  inches  above  the  patella. 
COMMON  Ex-  The  tendon  of  the  rectus,  gradually  expanding, 

TENSOR  TENDON.  becomes  connected  on  its  under  surface  with  the 
tendon  of  the  crureus,  and  on  either  side  with  that  of  the  vasti, 
and  is  firmly  fixed  into  the  upper  part  and  sides  of  the  patella. 
From  this  bone  the  common  extensor  tendon,  the  ligamentum 
patellce,  descends  over  the  front  of  the  knee-joint,  and  is  inserted 
into  the  rough  part  of  the  tubercle  of  the  tibia.  Besides  this,  the 
lower  fibres  of  the  vasti  terminate  on  a  sheet-like  tendon,  which 
runs  wide  of  the  patella  on  either  side,  and  is  directly  inserted 
into  the  sides  of  the  head  of  the  tibia  and  fibula,  so  that  the  knee 
is  completely  protected  all  round.  The  patella  is  a  large  sesamoid 
bone,  interposed  to  facilitate  the  play  of  the  tendon  over  the  con- 
dyles  of  the  femur:  it  not  only  materially  protects  the  joint,  but 
adds  to  the  power  of  the  extensor  muscles,  by  increasing  the  angle 
at  which  the  tendon  is  inserted  into  the  tibia. 

To  facilitate  the  play  of  the  extensor  tendon  there  are  two 


EXTENSOR    MUSCLES.  517 

bursse.  One  is  placed  between  the  ligamentum  patellae  and  the 
smooth  part  of  the  tubercle  of  the  tibia,  the  other  between  the 
crureus  and  the  lower  part  of  the  femur.  This  last  is  of  consider- 
able size.  In  early  life  it  is,  as  a  rule,  distinct  from  the  synovial 
membrane  of  the  knee-joint ;  but  after  a  few  years  a  wide  com- 
munication frequently  exists  between  them. 

ACTION  OF  The  extensor  muscles  of  the  thigh  are  among 

THE  EXTENSOE  the  most  powerful  in  the  body.  Great  power  of 
MUSCLES.  extending  the  knee  is  one  of  the  essential  con- 

ditions of  the  erect  attitude.  Without  it,  how  could  we  rise  from 
the  sitting  position  ?  When  erect,  how  could  we  walk,  run,  or 
spring?  The  rectus,  by  taking  origin  from  the  pelvis,  gains  a 
double  advantage  ;  it  acts  upon  two  joints  simultaneously,  bending 
the  thigh  while  it  extends  the  knee,  as  when  we  advance  the  leg  in 
walking :  it  also  contributes  to  balance  the  pelvis  on  the  head  of 
the  thigh  bone,  and  thus  prevents  the  body  from  falling  backwards. 
We  cannot  have  a  better  proof  of  the  power  of  the  extensor 
muscles  than  when  the  patella  is  broken  by  their  sudden  con- 
traction ;  an  injury  which  sometimes  happens  when  a  man, 
slipping  backwards,  makes  a  violent  effort  to  recover  his  balance. 

BTTBSA  OVER  The  skin  over  the  patella  is  exceedingly  loose, 

THE  PATELLA.  and  in  the  subcutaneous  tissue  is  a  bursa  of 
considerable  size.  Since  this  bursa  is  apt  to  enlarge  and  inflame 
in  females  who  are  in  the  habit  of  kneeling  at  their  work,  it  is 
generally  called  the  housemaid's  bursa.  The  bursa  is  not  seated 
precisely  over  the  patella,  but  extends  some  way  down  the  liga- 
mentum patellae;  indeed,  in  some  cases  it  is  entirely  confined  to 
this  ligament.  This  corresponds  with  the  position  of  the  tumour 
which  the  bursa  occasions  when  enlarged.  Generally  speaking,  in 
subjects  brought  for  dissection,  the  wall  of  the  bursa  is  more  or 
less  thickened,  and  its  interior  intersected  by  numerous  fibrous 
cords,  remnants  of  the  original  cellular  structure  altered  by  long- 
continued  friction.  Again,  the  wall  of  the  bursa  does  not  always 
form  a  complete  sac  ;  sometimes  there  is  a  wide  opening  in  it ; 
this  explains  the  rapidity  with  which  inflammation,  in  some  cases, 
extends  from  the  bursa  into  the  surrounding  areolar  tissue. 


518     COURSE  AND  RELATIONS  OF  FEMORAL  ARTERY. 

Below  the  bursa  is  a  layer  of  fascia  lata,  and  under  this  is  a 
network  of  arteries.  The  immediate  covering  of  the  bone,  or 
what  may  be  called  its  periosteum,  is  a  strong  expansion  derived 
from  the  extensor  tendon.  This  is  interesting  for  the  following 
reason  :  in  ordinary  fractures  of  the  patella  from  muscular  action 
the  tendinous  expansion  over  it  is  torn  also  ;  the  ends  of  the  bone 
gape  widely,  and  never  unite  except  by  ligament.  But  in  fractures 
from  direct  mechanical  violence,  the  tendinous  expansion,  being 
entire,  maintains  the  fragments  in  apposition,  so  that  there  is 
commonly  a  bony  union. 

c  The  femoral  artery  is  a  continuation  of  the 

RELATIONS  OF          external  iliac.     Passing  beneath  the  crural  arch 
THE  FEMOKAL  at  a  point  midway  between  the  spine  of  the  ilium 

and  the  symphysis  pubis,  it  descends  along  the 
front  and  inner  side  of  the  thigh.  At  the  junction  of  the  upper 
two-thirds  with  the  lower  third  of  the  thigh,  it  passes  through  an 
opening  in  the  tendon  of  the  adductor  magnus,  and  entering  the 
ham,  takes  the  name  of  popliteal.  A  line  drawn  from  the  point 
indicated  of  the  crural  arch  to  the  adductor  tubercle  on  the  internal 
condyle  corresponds  with  the  course  of  the  artery.  Its  distance 
from  the  surface  increases  as  it  descends.  Immediately  under, 
and  for  a  short  distance  below  the  crural  arch,  it  is  supported  by 
the  inner  border  of  the  psoas  ;  lower  down  it  runs  in  front  of  the 
pectineus,  but  separated  from  it  by  the  profunda  vessels ;  still 
lower  down  it  lies  upon  the  adductor  longus,  and  then  upon  the 
adductor  magnus. 

That  part  of  the  artery  which  extends  from  the  crural  arch  to 
the  giving  off  of  the  profunda,  is  called  the  common  femoral 
artery ;  its  continuation  beyond  the  profunda  is  termed  the  super- 
ficial femoral ;  and  it  is  the  latter  vessel  which  is  ligatured  for 
aneurysm  of  the  popliteal  artery. 

In  the  upper  third  of  the  thigh,  the  artery  is  situated  in 
Scarpa's  triangle,  and  is  comparatively  superficial,  being  covered 
only  by  the  muscular  fascia,  and  the  sheath  of  the  femoral  vessels. 
About  the  middle  third  it  is  more  deeply  seated,  and  is  covered 
by  the  sartorius ;  and  lower  down  by  a  tendinous  aponeurosis, 


HUNTER'S  CANAL.  519 

which  stretches  from  the  adductor  longus  and  magnus  over  to  the 
vastus  interims.  This,  which  forms  part  of  Hunter's  canal,  will  be 
examined  presently. 

At  the  crural  arch  the  anterior  crural  nerve  is  placed  on  the 
outer  side  of  the  artery  (separated  from  it  by  a  few  fibres  of  the 
psoas),  and  the  femoral  vein  on  the  inner  side :  as  the  vein 
descends,  it  gradually  passes  behind  the  artery.  Artery  and  vein 
lie  close  together,  and  are  enclosed  in  a  common  sheath. 

HUNTER'S  In  the  middle  third  of  the  thigh,  the  femoral 

CANAL.  artery  is  contained  in  a  tendinous  canal*  beneath 

the  sartorius,   called  Hunter's   canal.      This  canal  at  its  upper 
part  is  rather  indistinct ;  but  it  gradually  becomes  stronger  to- 
wards the  opening  in  the  tendon  of  the  ad-  FIG.  120. 
ductor   magnus.     Its  boundaries  are  formed 
by  the  tendons  of  the  muscles  between  which 
the  artery  runs.     On  the   inner  side  are  the 
tendons  of  the  adductor  longus  and  magnus ; 
on  the  outer  side  is  the  tendon  of  the  vastus 
internus  ;  in  front  the  canal  is  completed  by 

1  •*  SECTION    THROUGH 

an   aponeurotic   expansion   thrown   obliquely        HUNTER'S  CANAL. 
across  from  the  adductors  to  the  vastus  inter-  *•  vastns  internus. 

2.  Adductor  longus. 

nus,  as  shown  in  fig.  1 20.  In  a  horizontal  section  3.  Aponeurosis  thrown  across 
the  canal  appears  triangular.  The  adaptation  of  this  shape  to  the 
exigencies  of  the  case  is  manifest  when  we  reflect  that  the  muscles 
keep  the  sides  of  the  triangle  always  tight,  and  thereby  prevent 
any  compression  of  the  vessels. 

Hunter's  canal  contains  not  only  the  femoral  artery  and  vein, 
but  the  internal  saphenous  nerve.  The  vein  lies  behind  and  to 
the  outer  side ;  the  nerve  crosses  fcom  the  outer  to  the  inner 
side  of  the  artery. 

A  ligature  can  be  placed  around  the  artery,  in  the  upper  third 
of  the  thigh,  with  comparative  facility;  not  so  easily  in  the 
middle  third.  The  artery  is  tied  .for  an  aneurysm  of  the  popliteal, 

*  Called  Hunter's  canal,  because  it  was -in  this  part  of  its  course  that  John 
Hunter  first  tied  the  femoral  artery  for  aneurysm  of  the  popliteal,  in  St.  George's  Hos- 
pital, A.D.  1785.  The  particulars  of  this  interesting  caee-are  published  in  the  'Trans, 
for  the  Improvement  of  Med.  and  Chir.  Knowledge.' 


520  PEOPUNDA   FEMOEIS. 

just  where  the  sartorius  begins  to  overlap  it,  for  three  reasons: — 
1,  it  is  more  accessible ;  2,  the  coats  of  the  artery  at  this  distance 
are  less  likely  to  be  diseased  ;  3,  the  origin  of  the  profunda  is 
sufficiently  far  off  to  admit  of  the  formation  of  a  clot.  An  incision, 
beginning  about  three  inches,  below  the  crural  arch,  should  be 
made  about  three  inches  long  over  the  line  of  the  artery.  The 
muscular  fascia  should  be  divided  on  a  director  to  the  same  extent. 
Then,  by  gently  drawing  aside  the  inner  border  of  the  sartorius, 
the  artery  is  seen  enclosed  in  its  sheath  with  the  vein.  An  opening 
should  be  made  into  the  sheath,  which  must  be  carefully  separated 
from  the  artery  to  an  extent  sufficient  to  allow  the  passage  of 
the  aneurysmal  needle.  The  needle  should  be  turned  round  the 
artery  from  within  outwards,  great  care  being  taken  not  to  injure 
the  vein.  The  nerves  to  be  avoided  are — the  long  saphenous,  which 
runs  along  the  outer  side  of  the  artery,  and  the  internal  cuta- 
neous which  crosses  obliquely  over  it. 

Having  already  traced  the  superficial  branches  of  the  femoral 
artery  in  the  groin,  namely,  the  superficial  epigastric,  the  external 
pudic,  and  the  superficial  circumflexa  ilii  (p.  497),  we  pass  on- 
now  to  the  profunda. 

PROFUNDA.  The    profunda^    the    chief    branch    of    the 

ARTERY  AND  femoral,    is   the    proper    nutrient    artery    of  the 

BRANCHES.  muscles  of  the  thigh,  and  is  by  many  considered 

as  a  division,  rather  than  a  branch,  of  the  common  femoral 
artery.  It  is  given  off  from  the  outer  and  back  part  of  the 
femoral,  from  one  and. a  half  to  three  inches  below  the  crural 
arch,  and  runs  down  behind  the  femoral  till  it  reaches  the  tendon 
of  .the  adductor  longus  ;  here  the  profunda  passes  behind  the 
adductor,  and  is  finally  lost  in  the  hamstring  muscles.*  In  most 
subjects,  the  profuoda,  for  a  short  distance  after  its  origin,  lies 
rather  on  "the  -outer  side  of  the  femoral  and  on  a  deeper  plane, 
over  the  iliacus  intern  us :  in  this  situation  it  might  be  mistaken 

*  The  point  at  which  the  profunda  is  given  off  below  the  crural  arch  varies  very 

much  even  in  .the  two  limbs  of  the  same  body.     We  have  measured  it  in   19  bodies, 

or  38  femoral  arteries.     It  varied  from  ^  to  3  inches.     In  22  cases  the  profunda  came 

off  between  1£  and  2  inches  ;.in  9  this  distance  was  exceeded;  in  7  this  distance  was 

.  kss. 


BRANCHES  OF  PROFUNDA.  521 

for  the  femoral  itself — indeed,  such  an  error  has  occurred  in 
practice.  It  soon,  however,  gets  behind  the  femoral,  and  lies 
upon  the  pectineus,  the  adductor  brevis  and  magnus ;  it  is 
separated  from  the  femoral  artery  at  first,  by  their  corresponding 
veins ;  lower  down,  by  the  adductor  longus. 

The  branches  of  the  profunda  generally  arise  in  the  following 
order  : — 1,  the  internal  circumflex  ;  2,  the  external  circumflex ;  3, 
the  perforating. 

The  internal  circumflex  is  given  off  from  the  inner  and  back  part  of 
the  profunda,  and  then  sinks  deeply  into  the  thigh  between  the  psoas  and 
pectineus.  At  the  lower  border  of  the  obturator  externus  it  divides  into 
two  branches  :  one— the  ascending — supplies  the  muscles  in  its  neighbour- 
hood, namely,  the  pectineus,  psoas,  adductors,  gracilis,  and  obturator  ex- 
ternus, anastomosing  with  the  obturator  artery ;  the  other — tbe  transverse 
— will  be  seen  in  the  dissection  of  the  back  of  the  thigh,  between  the 
adductor  magnus  and  the  quadratus  femoris.  This  latter  sometimes 
gives  off  a  small  branch  to  the  hip-joint,  which  runs  through  the  notch  in 
the  acetabulum  to  the  ligamentum  teres  ;  it  afterwards  inosculates  with 
the  ischiatic  and  superior  perforating  arteries. 

The  external  circumflex  artery  comes  off  from  the  outer  side  of  the 
profunda,  runs  transversely  outwards  beneath  the  sartorius  and  rectus 
between  the  branches  of  the  anterior  crural  nerve,  and  then  subdivides 
into  three  sets  of  branches,  ascending,  transverse,  and  descending.  The 
ascending  run  up  to  the  outer  side  of  the  ilium,  beneath  the  tensor  fascise 
and  gluteus  medius,  supply  these  muscles,  and  inosculate  with  the  termi- 
nal branches  of  the  gluteal  artery.  The  transverse  pass  directly  outwards 
over  the  crureus,  then  enter  the  vastus  externus,  and  get  between  the 
muscle  and  the  femur.  They  inosculate  with  the  ischiatic,  the  internal 
circumflex,  the  gluteal,  and  the  perforating  arteries.  The  descending, 
one  or  more  in  number,  of  considerable  size,  run  down  between  the 
rectus  and  crureus,  and  supply  both  these  muscles :  one  branch,  larger 
than  the  rest,  runs  down  in  the  substance  of  the  vastus  externus,  along 
with  the  nerve  to  that  muscle,  and  inosculates  with  the  articular  branches 
of  the  popliteal. 

The  perforating  branches  of  the  profunda  are  so  named  because  they 
pass  through  the  adductors  to  supply  the  hamstring  muscles.  There  are 
generally  four.  The  first  passes  through  the  adductor  brevis  and  magnus, 
and  communicates  with  the  internal  circumflex  and  ischiatic  arteries. 


522 


ARTERIAL    INOSCULATIONS. 


The  second,  the  largest,  passes-  through  the  tendons  of  the  adductor  brevis 
and  magnus,  and  usually  furnishes  the  nutrient  artery  of  the  femur.  The 
third,  passes  through  the  tendon  of  the  adductor  magnus.  The  fourth, 
or  terminal  branch,  passes  through  the  tendon  of  the  adductor  magnus,  and 
supplies  the  hamstring  muscles,  and  inosculates  with  the  perforating  and 
articular  arteries.  They  not  only  supply  the  hamstring  muscles — namely, 

FIG.  121. 


1.  Crural  arch. 

2.  Internal  iliac. 

3.  Superficial  femoral. 

4.  Profunda. 

5.  Internal  circumflex. 

6.  External  circumflex. 


7.  First  perforating. 

8.  Second  ditto. 

9.  Third  ditto. 

10.  Gluteal. 

11.  Obturator. 

12.  Ischiatic. 

13.  Anastomotica  magna. 


PLAN    OF    THE    INOSCULATIONS    OF    THE    CIRCUMFLEX   ARTERIES. 

the  biceps,  semitendinosus,  and  semimembranosus — but,  the  vastus  ex- 
ternus  and  even  the  gluteus  maximus.  The  perforating  arteries  inoscu- 
late with  one  another,  with  the  internal  and  external  circumflex,  and  with 
the  ischiatic  arteries. 


ARTERIAL  IN- 
OSCULATIONS. 


If   the   common  femoral  were  tied  above  the 
origin  of  the  profunda,  how  would  the  circulation 


ANOJEEIOE    CRURAL    NERVE.  523 

be  carried  on  ?  The  ascending  branch  of  the  external  circumflex 
communicates  with  the  gluteal  and  the  circumflex  iliac ;  the  in- 
ternal circumflex  communicates  with  the  obturator  and  ischiatic 
(see  fig.  121).  Again — how  is  the  circulation  maintained  when 
the  superficial  femoral  is  tied  beloiv  the  profunda  ?  The  descend- 
ing branch  of  the  external  circumflex  and  the  perforating  branches 
of  the  profunda  communicate  with  the  articular  branches  of  the 
popliteal  and  the  tibial  recurrent.* 

The  anastomotica  magna  arises  from  the  femoral  artery  just 
before  it  leaves  its  tendinous  canal.  It  emerges  through  the 
canal,  and  runs  in  front  of  the  tendon  of"  the  adductor  magnus,  in 
company  with  the  long  saphenous  nerve  to  the  inner  side  of  the 
knee.  Here  it  divides  into  two  branches :  one,  the  superficial, 
accompanies  the  saphenous  nerve,  and  is  subsequently  distributed 
to  the  skin ;  the  other,  the  external?,  ramifies  over  the  capsule  and 
communicates  with  the  other  articular  arteries.f 

ANTEHIOR  The  anterior  crural  nerve  is  the  largest  branch 

CKUBAL  NEKVE.  of  the  lumbar  plexus  (p.  409).  It  comes  from  the 
third  and  fourth  lumbar  nerves,  sometimes  also  from  the  second. 
It  passes  beneath  the  crural  arch,  lying  in  the  groove  between 
the  iliacus  interims  and  psoas^  about  a  quarter  of  an  inch  to  the 
outer  side  of  the  artery,  and  soon  divides  into  branches,  some  of 
which  are  cutaneous,  but  the  greater  number  supply  the  extensor 
muscles  of  the  thigh.  The  cutaneous  branches,  already  described 
(p.  499),  and  the  long  saphenous  nerve,  are  given  off  from  the 
superficial  part  of  the  trunk:;  the  muscular  from  the  deep  part. 

The  long  saphenous-  nerve  descends  close  to  the  outer  side  of  the  fe- 
moral artery,  and  enters  the  tendinous  canal  with  it  in  the  middle  third 
of  the  thigh.  In  the  canal  it  crosses  over  the  artery  to  its  inner  side. 
The  nerve  leaves  the  artery  just  before  it  becomes  popliteal,  and  then 

*  Read  the  account  of  the  dissection  of  an  aneurysmal  limb  by  Sir  A.  Cooper, 
'  Med.  Chir.  Trans.'  vol.  ii. 

f  In  its  course  down  the  thigh  the  femoral  artery  gives  off  several  small  branches 
to  the  sartorius,  and  one  of  considerable  size  for  the  supply  of  the  vastus  internus. 
We  may  trace  this  branch  through  the  substance  of  the  vastus  down  to  the  patella, 
where  it  joins  the  network  of  vessels  on  the  surface  of  that  bone. 


524  OBTURATOR   NERVE. 

runs  in  company  with  the  anastomotica  magna  to  the  inner  side  of  the 
knee,  where  it  becomes  superficial,  between  the  gracilis  and  the  sartorius. 
In  the  middle  third  of  the  thigh  it  gives  off"  a  small  branch  which  com- 
municates beneath  the  fascia  lata  with  the  internal  cutaneous  and  obtu- 
rator nerves;  and  lower  down  another  branch  is  distributed  to  the  skin 
over  the  patella.  Its  further  relations  will  be  seen  in  the  dissection  of 
the  leg  and  foot. 

The  muscular  branches  are  to  be  traced  to  the  sartorius,  rectus,  crureus, 
and  subcrureus ;  the  branch  to  the  vastus  externus  accompanies  the  de- 
scending branch  of  the  external  circumflex  artery,  and  sends  a  filament 
to  the  knee-joint ;  that  to  the  vastus  in  ternus  runs  parallel  with,  but 
external  to,  the  long  saphenous  nerve,  and  supplies  filaments  to  the 
knee-joint.  One  branch  passes  under  the  femoral  artery  and  vein  to  enter 
the  anterior  surface  of  the  pectineus. 

The  obturator  nerve,  also  a  branch  of  the  lumbar  plexus 
(p.  409),  supplies  the  adductor  muscles.  It  enters  the  thigh 
through  the  upper  part  of  the  obturator  foramen  above  the  corre- 
sponding artery,  and  immediately  divides  into  two  branches,  of 
which  one  passes  in  front  of,  the  other  behind,  the  adductor  brevis. 
The  anterior  branch  subdivides  for  the  supply  of  the  gracilis,  the 
adductor  longus,  and  sometimes  the  adductor  brevis  and  pecti- 
neus ;  it,  moreover,  sends  a  filament  to  the  hip-joint,  another  to  the 
femoral  artery ;  and  a  third  forms  a  plexiform  communication  at  the 
lower  border  of  the  adductor  longus  with  the  internal  cutaneous 
and  long  saphenous  nerves.  The  posterior  -branch  supplies  the 
obturator  externus,  the  adductor  brevis  and  magnus.  In  some 
bodies  you  can  trace  a  filament  of  this  nerve  through  the  notch 
of  the  acetabulum  into  the  hip-joint,  and  another,  which  runs 
near  the  popliteal  artery  into  the  back  part  of  the  knee-joint. 
We  have  frequently  seen  cutaneous  branches  from  the  obturator 
on  the  inner  side  of  the  thigh.  This  is  interesting  practically, 
since  it  helps  to  explain  the  pain  often  felt  on  the  inner  side 
of  the  knee  in  disease  of  the  hip-joint. 

The  obturator  artery,  after  passing  through  the  foramen, 
divides  into  two  branches,  an  internal  and  an  external,  which 
form  a  circle  round  the  obturator  membrane.  These  supply 
the  external  obturator  and  adductors  of  the  thigh,  and  inosculate 


DISSECTION    OF    THE    FRONT    OF    THE    LEG.  525 

with  the  internal  circumflex  artery  (p.  522).  The  latter  branch 
sometimes  gives  off  the  small  artery  to  the  ligamentum  teres  of 
the  hip-joint. 


DISSECTION    OF    THE   FRONT    OF   THE   LEG. 

The  foot  should  be  turned  inwards,  and  fixed  in  this  position. 
An  incision  must  be  made  from  the  knee,  down  the  front  of  the 
leg,  over  the  ankle,  along  the  top  of  the  foot  to  the  great  toe  ;  a 
second,  at  right  angles  to  the  first.,  on  either  side  of  the  ankle  ; 
a  third,  across  the  bases  of  the  toes.  Eeflect  the  skin  from  the 
front  and  sides  of  the  leg  and  foot. 

CUTANEOUS  Having  traced  the  internal  saphena  vein 

VEIWSAND  (p.  499)  to  the  inner  side  of  the  knee,  follow 

NEEVES.  it  down  the  inner  side  of  the  leg,  in  front  of  the 

inner  ankle*  to  the  dorsum  of  the  foot.  On  the  dorsum  of  the 
foot  notice  that  the  principal  veins  form  an  arch,  with  the  con- 
vexity forwards,  as  on  the  back  of  the  hand.  This  arch  receives 
the  veins  from  the  toes.  From  the  inner  side  of  the  arch  the 
internal  saphena  originates :  from  the  outer  side,  the  external 
saphena.  The  latter  vein  runs  behind  the  external  ankle,  up  the 
back  of  the  calf  of  the  leg  to  join  the  popliteal  vein. 

LONG  SAPHE-  The  skin  on  the  inner  side  of  the  leg  is  supplied 

NOUS  NERVE.  by  the  long  or  internal  saphenous  nerve  (p.  523). 

It  becomes  subcutaneous  on  the  inner  side  of  the  knee,  between 
the  gracilis  and  sartorius.  Here  it  meets  the  saphena  vein,  and 
accompanies  it  down  the  leg,  distributing  its  branches  on  either 
side,  till  it  is  finally  lost  on  the  inner  side  of  the  foot  and  the 
great  toe.  The  largest  branch  curves  round  the  inner  side  of  the 
knee,  just  below  the  patella,  to  supply  the  skin  in  this  situation. 
It  pierces  the  sartorius  close  to  the  knee,  and  forms  with 
branches  from  the  internal,  middle,  and  external  cutaneous  nerves, 
the  plexus  patellae. 

*  The  French  commonly  bleed  from  the  internal  saphena  vein  as  it  crosses  over 
the  inner  ankle,  this  being  a  convenient  and  safe  place  for  venesection. 


526  MUSCULAR    FASCIA   AND    ANNULAR    LIGAMENTS. 

The  internal  cutaneous  nerve  supplies  the  skin  of  the  upper 
and  inner  aspect  of  the  leg,  and  joins  the  internal  saphenous 
nerve. 

The  skin  on  the  front  and  outer  parts  of  the  upper  half  of  the 
leg  is  supplied  by  cutaneous  branches  from  the  external  popliteal  or 
peroneal  nerve ;  the  skin  of  the  lower  half,  by  its  external  cutaneous 
branch  as  follows  : — 

EXTERNAL  Cu-  This  branch  of  the  peroneal  irerve  comes 
TANEOUS  BRANCH  through  the  fascia  about  the  lower  third  of 
OF  THE  PEEONEAL  ^e  outer  side  of  the  leg;  and  descending  over 
the  front  of  the  ankle,  divides  into  two.  Trace 
them,  and  you  will  find  that  the  inner  and  smaller  supplies  the 
inner  side  of  the  great  toe,  and  the  contiguous  sides  of  the 
second  and  third  toes  ;  towards  its  termination  it  communicates 
with  the  long  saphenous  and  anterior  tibial  nerves.  The  outer 
distributes  branches  to  the  outer  side  of  the  third  toe,  both  sides 
of  the  fourth,  and  the  inner  side  of  the  fifth  toe,  and  joins  the 
short  (or  external)  saphenous  nerve. 

The  outside  of  the  little  toe  is  supplied  by  the  short  saphe- 
nous nerve,  which  runs  behind  the  outer  ankle  with  the  corre- 
sponding vein. 

The  contiguous  sides  of  the  great  and  second  toes  are  supplied 
by  the  termination  of  the  anterior  tibial  nerve.* 

-»,  This  is  remarkably  thick  and  strong.     Besides 

FASCIA  AND  AN-  its  general  purpose  of  forming  sheaths  for  the 
NUI.AK  LIGA-  muscles,  and  straps  for  the  tendons,  it  gives  origin, 

MENTS.  ag  in  the  forearm,  to  muscular  fibres ;  so  that  it 

cannot  be  removed  near  the  knee,  without  leaving  the  muscles 
ragged.  The  fascia  is  attached  to  the  head  of  the  tibia  and  the 
fibula:  it  is  identified  on  the  inner  side  with  the  expanded 
tendons  of  the  sartorius,  gracilis,  and  semi-tendinosus  ;  on  the 
outer  side  with  that  of  the  biceps:  consequently,  when  these 
muscles  act,  it  is  rendered  tense.  Following  it  down  the  leg,  you 
find  that  it  is  attached  to  the  edge  of  the  tibia,  and  that  it 

*  Such  is  the  most  common  distribution  of  the  nerves  to  the  upper  surface  of  the 
toes.    But  deviations  from  this  arrangement  are  frequent. 


MUSCLES  ON  THE  FRONT  OF  THE  LEG.          527 

becomes  stronger  as  it  approaches  the  ankle,  to  form  the  liga- 
ments which  confine  the  tendons  in  this  situation.  Of  these  liga- 
ments, called  annular,  there  are  three,  as  follows  : — 

a.  The  anterior  annular  extends  obliquely  across  the  front  of 
the  ankle-joint,  and  confines  the  extensor  tendons  of  the  ankle 
and  toes.     It  consists  of  two  converging  straps,  which  join,  and  are 
continued  on  as  a  common  band,  like  the  letter  H<  placed  trans- 
versely.    The  common  band  is  attached  to  the  external  malleolus, 
cuboid  and  os  calcis :  it  is  continued  horizontally  inwards,  and  in 
front  of  the  ankle  splits  into  two  fasciculi  ;  the  upper  is  attached 
to  the  tibia ;    the  lower  into  the  scaphoid  and    internal  cunei- 
form.    It  is  the  strain  of  this  ligament  which  occasions  the  pain 
in  sprains  of  the  ankle.     You  will  see  presently  that  it  makes  a 
pulley  for  the  extensor  longus  digitorum. 

b.  The  external  annular  extends  from  the  outer  malleolus 
to  the  os  calcis,  and  confines  the  tendons  of  the  peronei  muscles, 
which  draw  the  foot  outwards. 

c.  The  internal  annular  is  ill  defined,  and  extends  from  the 
inner  malleolus  to  the  os  calcis,  and  binds  down  the  flexor  tendons 
of  the  foot  and  toes. 

Eemove  the  fascia,  leaving  enough  of  the  annular  ligaments  to 
retain  the  tendons  in  their  places. 

MUSCLES  ON  The  muscles  on  the  front  of  the  leg  are: — 1, 

THE  FHONT  OF  the  tibialis  anticus ;  2,  the  extensor  longus  digi- 
torum and  peroneus  tertius ;  3,  the  extensor 
proprius  pollicis. 

TIBIALIS  The  tibialis  anticus  arises  from  the  external 

ANTICUS.  tuberosity  and  the  upper  two-thirds  of  the  outer 

side  of  the  tibia,  from  the  interosseous  membrane,  from  the 
fascia  which  covers  it,  and  from  that  which  separates  it  from  the 
next  muscle.  About  the  lower  third  of  the  leg  the  fibres  termi- 
nate on  a  strong  flat  tendon,  which  descends  obliquely  over  the 
front  of  the  ankle  to  the  inner  side  of  the  foot ;  here  it  becomes  a 
little  broader,  and  is  inserted  into  the  internal  cuneiform  bone 
and  the  tarsal  end  of  the  metatarsal  bone  of  the  great  toe.  The 
synovial  membrane,  which  lines  the  sheath  of  the  tendon  beneath 


528         MUSCLES  ON  THE  FEONT  OF  THE  LEG. 

the  anterior  annular  ligament,  accompanies  it  to  within  an  inch 
of  its  insertion ;  consequently  it  is  opened  when  the  tendon  is 
divided  for  club-foot.  The  action  of  this  muscle  is  to  draw  the 
foot  upwards  and  inwards.*  When  the  foot  is  the  fixed  point,  it 
assists  in  balancing  the  body  at  the  ankle.  Its  nerve  comes  from 
the  anterior  tibial. 

EXTENSOR  This  muscle  lies  along  the  fibular  side  of  the 

LONGUS  DIGI-  preceding.  It  arises  from  the  external  tuberosity 
TOEUM.  0£  ^e  tjkja?  from  the  upper  three-fourths  of  the 

inner  surface  of  the  fibula,  from  the  interosseous  membrane,  from 
the  fascia  and  the  intermuscular  septa.  Its  fibres  terminate  in 
a  penniform  manner  upon  a  long  tendon,  situated  on  the  inner 
side  of  the  muscle :  this  tendon  descends  in  front  of  the  ankle 
and  divides  into  four  slips,  which  pass  to  the  four  outer  toes. 
They  diverge  from  each  other,  and  are- inserted  into  the  toes  thus  : 
— on  the  first  phalanx,  each  tendon  (except  that  of  the  little  toe) 
is  joined  on  its  outer  side  by  the  corresponding  tendon  of  the  ex- 
tensor brevis.  The  united  tendons  then  expand,  and  are  inserted 
as  on  the  fingers  ;  that  is,  the  middle  part  is  inserted  into  the  base 
of  the  second  phalanx ;  the  sides  run  on  to  the  base  of  the  third 
(p.  329).  Its  nerve  comes  from  the  anterior  tibial. 

Immediately  below  the  ankle  the  anterior  annular  ligament 
forms  a  pulley  through  which  the  tendon  of  this  muscle  plays.  It 
is  like  a  sling,  of  which  the  two  ends  are  attached  to  the  os  calcis, 
while  the  loop  serves  to  confine  the  tendon.  The  play  of  the  ten- 
don is  facilitated  by  a  synovial  membrane,  which  is  prolonged  for 
a  short  distance  along  each  of  its  four  divisions.  Besides  its  chief 
action,  this  muscle  extends  the  ankle-joint.f 

PERONEUS  This  appears  to  be  a  portion  of  the  preceding. 

TEHTIUS.  its  fibres  arise  from  the  lower  part  of  the  inner 

surface  of  the  shaft  of  the  fibula,  the  interosseous  membrane,  and 
the  intermuscular  septum,  and  terminate  on  their  tendon-like  barbs 

*  It  is  generally  necessary  to  divide  this  tendon  in  distortion  of  the  foot  inwards, 
called  talipes  varus. 

f  There  is  often  a  large  Imrsa  between  the  tendon  of  the  extensor  longus  digi- 
torum  and  the  outer  end  of  the  astragalus.  This  bursa  sometimes  communicates 
with  the  joint  of  the  head  of  the  astragalus.  • 


ANTERIOR    TIBIAL    ARTERY.  529 

on  a  quill.  The  tendon  passes  through  the  same  pulley  with  the 
long  extensor  of  the  toes,  and,  expanding  considerably,  is  inserted 
into  the  tarsal  end  of  the  metatarsal  bone  of  the  little  toe.  It  is 
supplied  by  a  branch  of  the  anterior  tibial  nerve. 

'The  peroneus  tertius  and  the  tibialis  anticus  are  important 
muscles  in  progression.  They  raise  the  toes  and  foot  from  the 
ground.  Those  who  have  lost  th£  use  of  these  muscles  are  obliged 
to  drag  the  foot  along  the  ground,  or  to  swing  the  entire  limb 
outwards,  in  walking. 

EXTENSOR  This  muscle  lies  partly  concealed  between  the 

PROPRITTS  tibialis  anticus  and  the  extensor  longus  digitorum. 

POLLICIS.  j£  arises  from  rather  more  than  the  middle  third 

of  the  inner  surface  of  the  fibula,  and  from  the  interosseous  mem- 
brane. The  fibres  terminate  in  a  penniform  manner  on  the  tendon, 
which  runs  over  the  ankle,  between  the  tendons  of  the  tibialis 
anticus  and  the  extensor  communis  digitorum,  along  the  top  of 
the  foot,  to  the  great  toe,  where  it  is  inserted  into  the  base  of  the 
last  phalanx.  It  has  a  special  pulley  beneath  the  annular  ligament, 
lined  by  a  synovial  membrane,  which  accompanies  it  as  far  as  the 
metatarsal  bone  of  the  great  toe.  It  is  supplied  by  the  anterior 
tibial,  a  branch  of  the  peroneal  nerve. 

Now  examine  the  course,  relations,  and  branches  of  the  anterior 
tibial  artery.  Since  it  lies  deeply  between  the  muscles,  it  is  neces- 
sary to  separate  them  from  each  other :  this  is  easily  done  by 
proceeding  from  the  ankle  towards  the  knee. 

COURSE  AND  '-Th6  anterior  tibial  artery  is  one  of  the  two 

RELATIONS  OF  THE  branches  into  which  the  popliteal  divides  at  the 
ANTERIOR  TIBIAL  lower  border  of  the  popliteus.  It  comes  at  first 
horizontally  forward  about  1£  inches  below  the 
head  of  the  fibula,  above  the  interosseous  membrane,  and  then 
descends,  lying  in  rather  more  than  the  first  half  of  its  course  upon 
the  interosseous  membrane,  afterwards  along  the  front  of  the  tibia. 
It  runs  beneath  the  annular  ligament  over  the  front  of  the  ankle, 
where  it  takes  the  name  of  the  dorsal  artery  of  the  foot.  Thus, 
a  line  drawn  from  the  head  of  the  fibula  to  the  interval  between 
the  first  and  second  metatarsal  bones  would  nearly  indicate  its 

M  M 


530  ANTERIOR    TIBIAL    AETERY. 

course.  In  the  upper  third  of  the  leg  it  lies  deeply  between  the 
tibialis  anticus  and  the.  extensor  longus  digitorum  ;  in  the  lower  two- 
thirds,  between  the  tibialis  anticus  and  the  extensor  proprius  pollicis. 
In  front  of  the  ankle  the  artery  is  crossed  by  the  extensor  proprius 
pollicis,  and  lies  between  the  tendon  of  this  muscle  and  the  inner 
tendon  of  the  extensor  longus  digitorum. 

The  artery  is  accompanied  by  the  anterior  tibial  nerve  (a  branch 
of  the  peroneal),  which  runs  for  some  distance  upon  its  fibular  side, 
then  in  front  of  it,  and  lower  down  is  again  situated  on  its  outer 
side.  It  is  accompanied  by  two  veins,  one  on  each  side,  which 
communicate  at  intervals  by  cross  branches. 

The  branches  of  the  anterior  tibial  are  as  follows  : — 

a.  The  recurrent  branch  ascends  close  by  the  outer  side  of  the  head 
of  the  tibia,  through  the  tibialis  anticus,  to  the  front  of  the  knee-joint, 
where  it  inosculates  with  the  other  articula*  arteries  derived  from  the 
popliteal. 

b.  Irregular  muscular  branches,  in  its  course  down  the  leg. 

c.  The  malleolar  branches,  external  and  internal,  ramify  over  the 
ankle  :  the  external,  descending  beneath  the  tendon  of  the  extensor  longas 
digitorum,  ramifies   on   the  external   malleolus,    inosculating  with  the 
anterior  peroneal  and  the  tarsal  arteries ;  the  internal  passes  beneath 
the  tibialis  anticus,  and  anastomoses  with  the  posterior  tibial.     They 
supply  the  joint,  the  articular  ends  of  the  bones,  and  the  sheaths  of  the 
tendons  around  them. 

EXTENSOR  This  muscle  is  situated  on  the  dorsum  of  the 

BREVIS  DIGI-  foot,  beneath  the  long  extensor  tendons  of  the  toes. 

It  arises  from  the  outer  part  of  the  os  calcis,  from 
the  ligament  uniting  this  bone  to  the  astragalus,  and  from  the 
anterior  annular  ligament.  The  fibres  run  obliquely  over  the 
foot,  and  terminate  in  four  tendons,  which  pass  forwards  to  the 
four  inner  toes.  The  inner  one  is  inserted  by  an  expanded 
tendon  into  the  base  of  the  first  phalanx  of  the  great  toe  ;  the 
others  join  the  fibular  side  of  the  long  extensor  tendons  to  be  in- 
serted with  them  into  the  second  and  ungual  phalanges.  The 
tendon  to  the  great  toe  crosses  over  the  dorsal  artery  of  the  foot. 
It  is  supplied  by  a  branch  of  the  anterior  tibial  nerve. 


PEKONEI    MUSCLES.  531 

This  artery,  the  continuation  of  the  anterior 
AETEEY  OF  THE  tibial,  runs  over  the  instep  to  the  interval  between 
the  first  and  second  metatarsal  bones,  where  it 
sinks  into  the  sole  and  joins  the  deep  plantar  arch.  On  the 
dorsum  of  the  foot  it  runs  along  the  outer  side  of  the  extensor 
proprius  pollicis,  and  before  it  dips  down  into  the  sole,  is  crossed 
by  the  short  extensor  tendon  of  the  great  toe.  The  dorsal  artery 
gives  off  the  following  branches  : — - 

a.  The  tarsal  branch  arises  near  the  scaphoid  bone,   passes  beneath 
the  extensor  bre vis  digitorum  towards  the  outside  of  the  foot,  supplies 
the  bones  and  joints  of  the  tarsus;  and  inosculates  with  the  external 
malleolar,  the  peroneal,  the  metatarsal,-  and  the  external  plantar  arteries. 

b.  The  metatarsal  branch  generally  runs  towards  the  outside  of  the 
foot,  beneath  the  short  extensor  tendons,  near  the  bases  of  the  metatarsal 
bones,  and  gives  off  the  three  outer  interosseous  arteries.     These  pass 
forwards  over  the  corresponding  interosseous  muscle's,  supply  them,  and 
then  subdivide  to  supply  the  contiguous  sides  of  the  upper  surfaces  of 
the  toes.     They  communicate  by  perforating  branches  with  the  plantar 
arteries  at  each  end  of  the  interosseous  spaces. 

c.  The  dorsalis  hallucis  is,  strictly  speaking,  the  artery  of  the  first 
interosseous  space.  It  comes  from  the  dorsal  artery  of  the  foot  just  before 
this  sinks  into  the  sole,  and  runs  forwards  to  supply  digital  branches  to 
the  sides  of  the  great  toe,  and  the  inner  side  of  the  second  toe. 

PEEOKEI  These  muscles  are  situated  on  the  outer  side  ot 

MUSCLES.  the  fibula,  and  are  named,  respectively,  peroneus 

longus  and  brevis. 

PEBONEUS  This  arises  from  the  outer  surface  of  the  fibula 

LONGUS.  along  its  upper  two-thirds,  from  the  fascia  and 

the  intermuscular  septa.  The  fibres  terminate  in  a  penniform 
manner  upon  a  tendon,  which  runs  through  a  groove  behind  the 
external  malleolus,  then  along  the  outer  side  of  the  os  calcis,  and, 
lastly,  through  a  groove  on  the  under  surface  of  the  os  cuboides 
deep  into  the  sole.  It  crosses  the  sole  obliquely  forwards  and  in- 
wards, and  is  inserted  into  the  tarsal  end  of  the  metatarsal  bone 
of  the  great  toe.  In  its  course  through  these  several  bony  grooves 
the  tendon  is  confined  by  a  fibrous  sheath,  lined  by  a  synovial 

W  M   2 


532  PERONEI   MUSCLES. 

membrane.  In  removing  the  metatarsal  bone  of  the  great  toe,  if 
possible,  leave  the  insertion  of  this  tendon.  Its  nerve  comes  from 
the  peroneal. 

PERONEUS  This   muscle   lies  beneath   the   preceding.     It 

BKETIS-  arises  from  about  the  middle  third  of  the  outer 

surface  of  the  fibula,  internal  to  the  preceding  muscle,  and  from 
the  intermuscular  septa.  It  terminates  on  a  tendon  which 
runs  behind  the  external  malleolus,  through  the  same  sheath  with 
the  peroneus  longus,  then  proceeds  along  the  outside  of  the  foot 
and  is  inserted  into  the  tarsal  end  of  the  metatarsal  bone  of  the 
little  toe.*  Its  nerve  is  from  the  peroneal. 

The  action  of  the  peronei  is  to  raise  the  outer  side  of  the  foot.f 
This  movement  regulates  the  bearing  of  the  foot  in  progression,  so 
as  to  throw  the  principal  part  of  the  weight  on  the  ball  of  the  great 
toe.  Its  action  is  well  exemplified  in  skating.  Again,  supposing 
the  fixed  point  to  be  at  the  foot,  they  tend  to  prevent  Athe  body 
from  falling  on  the  opposite  side,  as  when  we  balance  ourselves  on 
one  leg. 

PERONEAL  Near  the  inner  side  of  the  tendon  of  the  biceps 

OR  MUSCULO-CU-  flexor  of  the  leg,  is  a  large  nerve,  the  external  popli- 
TANEOUS  NERVE.  teal  or  peroneal,  a  branch  of  the  great  ischiatic.  By 
reflecting  the  upper  part  of  the  peroneus  longus,  you  will  find  that 
this  nerve  runs  round  the  -outer  side  of  the  fibula  immediately 
below  its  head.  Here  it  divides  into  several  branches,  as  follows  : — 
1.  Articular  branches  to;  the  knee-joint,  which  pass  in  with  the 
external  articular  arteries,  and- the  tibial  recurrent  artery  ;  2.  The 
anterior  tibial,  which  accompanies  the  corresponding  artery  and 
supplies  the  muscles  between  which  it  runs,  namely  the  tibialis 
anticus,  extensor  longus  digitorum,  extensor  proprius  pollicis — and 
peroneus  tertius  :  also  the  extensor  brevis  digitorum  ;  3.  The  exter- 
nal-cutaneous (p.  526),  which  comes  through  the  fascia  between  the 

*  On  the  outside  of  the  os  calcis  there  is  a  ridge  which  separates  the  tendons  of 
the  peronei.  Each  has  a- distinct  sheath.  The  short  tendon  runs  above,  the  long  one 
below  the  ridge. 

f  In  distortion  of  the  foot  outwards,  called  talipes  valgus,  it  is  generally  neces- 
sary to  divide  the  tendons  of  the  peronei. 


GLUTEAL    REGION.  533 

peroneus  longus  and  the  extensor  longus  digitorum  ;  4.  Branches, 
which  supply  the  peronei  (longus  and  brevis)  muscles. 

If,  then,  the  peroneal  nerve  were  divided  in  the  popliteal  space, 
the  result  would  be  paralysis  of  the  tibialis  anticus,  the  extensors 
of  the  toes — long  and  short — and  all  the  peronei. 


DISSECTION    OF   THE   GLUTEAL   KEGION. 

The  body  having  been  placed  on  its  face,  the  pelvis  is  to  be 
raised  to  such  a  height  by  blocks  placed  beneath  it,  that  the  lower 
extremities  hang  down  over  the  end  of  the  table.  Then  rotate  the 
thighs  inwards  as  much  as  possible,  and  cross  them. 

The  incision  through  the  skin  should  commence  at  the  coccyx, 
and  be  continued  in  a  semicircular  direction  along  the  crest  of  the 
ilium.  Another  incision  should  be  made  from  the  coccyx  down- 
wards and  outwards  for  about  six  inches  below  the  great  trochanter. 
In  reflecting  the  skin,  notice  the  thick  cushion  which  the  sub- 
cutaneous adipose  tissue  forms  over  the  tuberosity  of  the  ischium. 
A  large  bursa  is  often  formed  between  the  cushion  and  the  bone. 

CUTANEOUS  These  are  derived   from  several  sources.     The 

NERVES.  posterior  divisions  of  ihe  first  and  second  lumbar 

nerves  descend  over  the  crest  of  the  ilium,  near  the  origin  of  the 
erector  spinse,  to  supply  the  skin  over  the  gluteus  maximus  as  far 
as  the  great  trochanter.  Internal  to  these,  are  the  posterior 
branches  of  the  three  upper  sacral  nerves,  which  are  distributed 
to  the  integument  over  the  sacrum  and  coccyx.  Over  the  middle 
of  the  crest,  come  the  lateral  branches  of  the  twelfth  dorsal,  and 
posterior  to  it,  the  iliac  branch  of  the  ilio-hypogastric.  Other 
cutaneous  nerves  ascend  from  below ;  they  are  branches  of  the 
lesser  ischiatic,  and  proceed  from  beneath  the  lower  border  of  the 
gluteus  maximus.  Lastly,  some  branches  from  the  external 
cutaneous  nerve  of  the  thigh  are  seen  on  the  outer  side  of 
this  region. 

GLUTEAL  Three   powerful    muscles    are    situated  in   the 

MUSCLES.  region  of  the  buttock,  one  above  the  other,  named, 

according  to  their  size,  the  gluteus  maximus,  medius,  and  minimus. 


534  GLUTEAL   REGION. 

The  fascia  covering  the  gluteus  maximus  is  comparatively  thin, 
posteriorly,  where  it  is  attached  to  the  sacrum,  coccyx,  and  ilium ; 
but  anteriorly  it  is  very  dense  and  glistening,  and  gives  origin  to 
the  fibres  of  the  gluteus  medius,  and  lower  down  becomes  con- 
tinuous with  the  fascia  lata. 

GLUTEUS  This  is  the  largest  muscle  of  the  body,  and  is 

MAXIMUS.  covered  by  a   fascia,  which   sends   prolongations 

inwards  between  the  muscular  bundles.  Its  great  size  is  cha- 
racteristic of  man,  in  reference  to  his  erect  position.  Its  texture 
is  thick  and  coarse.  It  arises  from  the  posterior  fifth  of  the 
crest  of  the  ilium,  and  from  the  rough  surface  below  it,  from  the 
lower  part  of  the  sacrum,  the  coccyx,  and  the  great  sacro-ischiatic 
ligament.  The  fibres  descend  obliquely  forwards,  and  are  inserted 
thus : — the  anterior  two-thirds  terminate  on  a  strong  broad 
aponeurosis  which  plays  over  the  great  trochanter,  and  joins  the 
fascia  lata  on  the  outside  of  the  thigh  (p.  500);  the  remaining 
third  is  inserted  into  the  femur,  along  the  ridge  (gluteal)  leading 
from  the  linea  aspera  to  the  base  of  the  great  trochanter. 

This  muscle  extends  the  thigh  bone  upon  the  pelvis,  and  is 
therefore  one  of  those  most  concerned  in  raising  the  body  from  the 
sitting  to  the  erect  position,  and  in  maintaining  it  erect.  It 
propels  the  body — in  walking,  running  or  leaping,  and  rotates  the 
thigh  outwards.  It  is  supplied  with  blood  by  the  gluteal  and 
ischiatic  arteries  ;  with  nerves  from  the  lesser  ischiatic,  and  the 
sacral  plexus. 

WHAT  is  SEEN  ^^e  gluteus  maximus  should  be  reflected  from 

BENEATH. THE  its  origin.     The  best  way  is  to  begin  at  the  front 

GLUTEOS  MAXI-  border,  which  overlaps  the  gluteus  medius.  The 
.dissection  is  difficult,  and  he  who  undertakes  it  for 
thejffirst- time,  is  almost  sure  to  injure  the  subjacent  parts.  The 
numerous  vessels  which  enter  its  under  surface  must  be  divided 
before  the  muscle  can  be  reflected.  This  having  been  accom- 
plished, the  following  objects  will  be  exposed  : — 

The  muscle  covering  the  ilium  is  the  gluteus  medius.  At  the* 
posterior  border  of  this  are  the  several  objects  which  emerge  from 
the  pelvis  through  the  great  ischiatic  notch — namely,  the  pyri- 


GLUTEAL    REGION.  535 

formis  muscle,  above  which  is  the  trunk  of  the  gluteal  vessels 
and  nerve,  and,  below  which,  are  the  greater  and  lesser  ischiatic 
nerves,  the  arteria  comes  nervi  ischiatici,  the  long  pudendal 
nerve,  the  ischiatic  vessels,  the  pudic  vessels  and  nerve,  and  the 
nerve  to  the  obturator  internus.  Coming  through  the  lesser 
ischiatic  notch,  is  the  tendon  of  the  obturator  internus,  and 
attached  to  it  are  the  gemelli  muscles,  one  above,  the  other  below 
it.  Extending  from  the  tuber  ischii  transversely  outward  to  the 
great  trochanter  is  the  quadratus  femoris,  and,  below  this,  is  seen 
the  upper  part  of  the  adductor  magnus.  The  origins  of  the  semi- 
membranosus,  biceps,  semitendinosus,  and  of  the  adductor 
magnus,  from  the  tuber  ischii,  are  also  seen  ;  as  well  as  the  great 
sacro-ischiatic  ligament,  which  passes  upwards  to  the  sacrum,  and  is 
pierced  by  the  coccygeal  branch  of  the  ischiatic  artery.  The  great 
trochanter  is  exposed,  together  with  a  small  portion  of  the  vastus 
externus ;  and  where  the  tendon  of  the  glutens  maximus  plays 
over  the  trochanter  major,  there  is  a  large  bursa,  simple  or  multi- 
locular.  Lastly,  the  side  of  the  sacrum,  the  coccyx,  part  of  the 
crest  of  the  ilium,  the  tuberosity  of  the  ischium,  and  the  coccygeus 
muscle  are  brought  into  view. 

GLUTEUS  This  muscle    arises  from  the  surface  of   the 

MEDIUS.  ilium,  between  the  crest  and  the  upper  curved 

line  ;  also  from  the  strong  fascia  which  covers  it  towards  the 
front.  The  fibres  converge  to  a  tendon,  which  is  inserted  into 
the  upper  and  outer  surface  of  the  great  trochanter  :  some  of  the 
anterior  fibres — in  immediate  connection  with  the  tensor  fasciae — 
terminate  on  the  aponeurosis  of  the  thigh.  Between  its  insertion 
and  the  bone  is  a  bursa. 

Keflect  the  gluteus  medius  to  see  the  third  gluteal  muscle. 
The  line  of  separation  between  them  is  marked  by  a  large  branch 
of  the  gluteal  artery. 

GLUTEUS  This  muscle  arises  from    the   surface  of    the 

MINIMUS.  ilium  below  the  upper  curved  line.    Its  fibres  pass 

over  the  capsule  of  the  hip-joint,  and  converge  to  a  tendon  which 
is  inserted  into  a  depression  on  the  front  part  of  the  great  tro- 
chanter, a  bursa  being  interposed.  This  muscle  and  the  pre- 


536  GLUTEAL   REGION. 

ceding  are  supplied  by  the  superior  gluteal  nerve,  a  branch  of  the 
lumbo-sacral.  The  chief  action  of  this  and  the  preceding  muscle 
is  to  assist  in  balancing  the  pelvis  steadily  on  the  thigh,  as  when 
we  are  standing  on  one  leg ;  with  the  fixed  point  at  the  ilium, 
they  are  abductors  of  the  thigh.  The  anterior  fibres  of  the  glutens 
medius  co-operate  with  the  tensor  fasciae  in  rotating  the  thigh 
inwards. 

GLUTEAL  The  gluteal  artery  is  the  largest  branch  of  the 

VESSELS  AND  internal    iliac    (p.  441).      Emerging    from    the 

NEKTES.  pelvis  through  the   great   ischiatic   foramen   be- 

tween the  pyriformis  and  the  gluteus  medius,  it  divides  into  large 
branches  for  the  supply  of  the  gluteal  muscles.  Of  these,  the 
more  superficial  proceed  forwards  between  the  gluteus  maximus 
and  medius,  both  of  which  they  supply,  and  eventually  anastomose 
with  the  posterior  sacral  and  ischiatic  arteries ;  others,  deeper, 
run  in  curves  between  the  gluteus  medius  and  minimus,  towards 
the  anterior  part  of  the  ilium.  Many  of  them  inosculate  with 
branches  of  the  external  circumflex,  the  deep  circumflexa  ilii,  and 
the  ischiatic  arteries. 

The  nerve  which  accompanies  the  gluteal  artery  is  a  branch  of 
the  lumbo-sacral  nerve  (p.  445).  It  subdivides  to  supply  the 
gluteus  medius  and  minimus,  and  the  tensor  fasciae ;  in  some 
subjects  it  sends  a  branch  to  the  gluteus  maximus  ;  but  this 
muscle  is  chiefly  supplied  by  the  lesser  ischiatic  nerve. 

A  surgeon  ought  to  be  able  to  cut  down  and  tie  the  gluteal 
artery  as  it  emerges  from  the  pelvis.  The  following  is  the  best 
rule  for  finding  it : — * 

Draw  a  line  from  the  posterior  superior  spine  of  the  ilium  to 
the  trochanter  major,  rotated  inwards.  The  junction  of  the  upper 
with  the  middle  third  of  this  line  lies  over  the  artery  as  it  emerges 
from  the  upper  border  of  the  great  ischiatic  notch. 

Now  examine  the  series  of  muscles  which  rotate  the  thigh 
outwards — namely,  the  pyriformis,  the  obturator  internus,  the 
gemelli,  the  quadratus  femoris,  and  the  obturator  externus. 

*  The  operation  of  tying  the  gluteal  artery  was  first  performed  by  John  Bell.   See 
h's  'Principles  of  Surgery,'  vol.  i.  p.  421. 


GLUTEAL    REGION.  537 

This  muscle  lies  immediately  below  and  parallel 
to  the  lower  fibres  of  the  gluteus  medius.  It 
arises  by  three  fleshy  fasciculi  from  the  second,  third,  and  fourth 
segments  of  the  front  surface  of  the  sacrum  between  the  foramina 
for  the  sacral  nerves,  and  -from  the  margin  of  the  great  sacro- 
ischiatic  notch.  The  fibres  converge  to  a  tendon  which  is  inserted 
into  the  upper  border  of  the  trochanter  major.  Its  nerve  comes 
from  the  sacral  plexus. 

OBTURATOH  This  muscle,  of  which  little  more  than  the 

INTERNUS.  tendon  can  be  seen  at  present,  arises  within  the 

pelvis,  from  the  ischium  between  the  great  ischiatic  notch  and 
the  obturator  foramen,  and  superiorly  as  high  as  the  brim  of 
the  pelvis,  from  the  obturator  membrane,  and  slightly  also  from 
the  obturator  fascia.  The  fibres  terminate  on  four  tendons 
which  converge  towards  the  lesser  ischiatic  notch,  pass  round  it 
as  over  a  pulley,  and  then  uniting  into  one,  are  inserted  into 
the  top  of  the  great  trochanter,  close  to  the  digital  fossa.  Divide 
the  tendon  about  three  inches  from  its  insertion,  to  see  the  four 
tendons  which  play  over  the  smooth  cartilaginous  surface.  There 
is  a  large  synovial  bursa  to  diminish  friction.  The  nerve  of  this 
muscle  comes  from  the  sacral  plexus  ;  sometimes  from  the  pudic 
nerve. 

GEMELLI  These  muscles  are  accessory  to  the  obturator 

internus,  and  are  situated,  one  above,  the  other 
below  it.  The  gemellus  superior  arises  from  the  spine  of  the 
ischium ;  the  gemellus  inferior  from  the  upper  and  back 
part  of  the  tuberosity.  Their  fibres  are  inserted  into  the  tendon 
of  the  obturator  internus.  Both  muscles  derive  their  nerves  from 
the  sacral  plexus.  ;  ,'• 

QUADRATUS  This  muscle  ai4ses  from  the  ridge  on  the  outer 

part  of  the  tuber  ischii.  Its  fibres  run  horizontally 
outwards,  and  are  inserted  into  the  back  of  the  great  trochanter, 
into  the  greater  part  of  the  linea  quadrati.  The  lower  border  of 
the  quadratus  femoris  runs  parallel  with  the  upper  edge  of  the 
adductor  magnus ;  in  fact,  it  lies  on  the  same  plane.  Between 
these  muscles  is  generally  seen  a  terminal  branch  of  the  internal 


538 


GLDTEAL    REGION. 


circumflex  artery.     Its  nerve  comes  from  the  sacral  plexus,  and 
enters  its  deep  surface. 

OBTUHATOB  To  see  this  muscle  reflect  the  quadratus  femoris. 

EXTERNUS.  It  arises  from  the  outer  surface  of  the  os  pubis, 

from  the  front  surface  of  the  ramus  of  the  pubes  and  ischium,  and 
from  the  obturator  membrane.     The  fibres  converge  to  a  tendon 

FIG.  122. 


12.  N.  of  pyrifomis. 

13.  N.  of  gemellus  superior. 

14.  N.  of  gemellus  inferior. 

15.  N.  of  quadratus  femoiip. 

16.  N.  of  gluteus  maximus. 

17.  Long  pudendal  n. 

18.  Cutaneous  n.  of  the  but- 

tock. 

19.  N.  of  the  long  head  of 

the  biceps. 

20.  N.  of  semi-tendinosus. 

21.  N.    of   semi-membrano- 

sus. 

22.  N.  of  short  head  of  the 

biceps. 


1,  2,  3,  4,  5.  Sacral  nn. 

6.  Superior  gluteal  n. 

7.  Great  ischiatic  n. 

8.  Lesser  ischiatic  n. 

9.  Pudic  n. 

10.  N.  of  obturator  internus. 

11.  N.  of  levatorani. 


PLAN   OF    THB   SACEAL    PLEXUS    AND    BRANCHES. 

which  runs  horizontally  outwards  over  a  groove  in  the  ischium, 
and  i?  inserted  into  the  deepest  part  of  the  digital  fossa  below  the 
gemellus  inferior.  Its  nerve  is  a  branch  of  the  posterior  division 
of  the  obturator  (p.  524). 

GREAT  ISCHI-  This  large  nerve  is  formed  by  the  union  of  the 

ATIC  NERVE.  last  lumbar  and  four  upper  sacral  nerves  (fig.  122), 

and  supplies  all  the  flexor  muscles  of  the  lower  extremity,  and  the 
extensors  of  the  foot. 


GLUTEAL    REGION. 


539 


Emerging  from  the  pelvis  through  the  great  sacro-ischiatic 
foramen  below  the  pyriformis,  it  descends  over  the  external  rotator 
muscles  of  the  thigh,  along  the  interval  between  the  tuber  ischii  and 
the  great  trochanter,  but  rather  nearer  to  the  former  ;  so  that,  in 
the  sitting  position,  the  nerve  is  protected  from  pressure  by  this 
bony  prominence.  The  nerve  does  not  descend  quite  perpendicu- 
larly, but  rather  obliquely  forwards  upon  the  adductor  magnus, 
parallel  with  the  great  sacro-ischiatic  ligament,  and  below  the 
middle  of  the  thigh  divides  into  the  internal  popliteal  and  the 
peroneal  (or  external  popliteal).  It  is  accompanied  by  a  branch 

FIG.  123. 


1.  Gluteus  medius. 

2.  Pyriformis. 

3.  Lesser  sciatic  nerve. 

4.  Obturator    interims, 

with  the  two  gemelli. 

5.  Coccygens. 


6.  Great  sciatic  nerve. 

7.  Quadratus  femoris. 

8.  Gluteus  maximus. 

9.  The  semitendinosus 

and  biceps. 

10.  Adductor  magnus. 


DEEP    MUSCLES    OF    THE    GLUTEAL    REGION. 


of  the  ischiatic  artery,  called  the  comes  nervi  ischiatici.*  The 
nerve  distributes  branches  to  the  hamstring  muscles  and  the 
adductor  magnus,  and  sends  a  small  branch  to  the  hip-joint  which 
pierces  the  posterior  part  of  the  capsular  ligament. 

LESSER  This  comes  from  the  lower  part  of  the  sacral 

ISCHIATIC  NEEVE.     plexus.     It   leaves   the    pelvis  with   the  greater 

*  The  arteria  comes  nervi  ischiatici  runs  generally  by  the  side  of  the  nerve,  but 
sometimes  in  the  centre  of  it.  This  artery  becomes  one  of  the  chief  channels  by  which 
the  blood  reaches  the  lower  limb  after  ligature  of  the  femoral.  See  in  the  Museum 
of  the  Royal  College  of  Surgeons  a  preparation  in  which  the  femoral  was  tied  by  John 
Hunter  fifty  years  before  the  man's  death. 


540 


GLUTEAL    REGION. 


ischiatic  nerve,  but  on  the  inner  side  of  it,  and  in  company  with 
the  ischiatic  artery.  The  muscular  branches  which  it  gives  off 
are  one  or  more — inferior  gluteal —  which  enter  the  under  surface 
of  the  gluteus  maximus.  All  its  other  branches  are  cutaneous. 
One  external  turns  round  the  lower  border  of  the  gluteus  maximus, 
and  supplies  the  skin  of  the  buttock.  Another,  the  inferior  or  long 
pudendal  (p.  419),  turns  inwards  towards  the  perineum,  to  supply 
the  skin  of  that  region  and  the  scrotum.  The  continued  trunk  runs 

FIG.  124. 


1.  Gluteal    artery 

and  nerve. 

2.  Pndic  artery  and 

nerve,     and 
nerve  to  obtu- 
rator internus. 

3.  Great  sacro- isch- 

iatic nerve. 


4.  Ischiatic  artery. 

5.  Internal  circum- 

flex artery. 

6.  The  first  perfor- 

ating artery. 


THE  ARTERIES  OF  THE  GLUTEAL  REGION. 

down  the  back  of  the  thigh  beneath  the  muscular  fascia,  as  low  as 
the  upper  part  of  the  calf,  supplying  the  skin  all  the  way  down, 
and  communicates  with  the  short  saphenous  nerve. 

ISCHIATIC  This  branch   of  the  internal   iliac   leaves   the 

ARTERY.  pelvis  between  the  pyriformis  and  the  gemellus 

superior  ;  it  then  descends  between  the  tuber  ischii  and  the  great 
trochanter,  along  the  inner  side  of  the  great  ischiatic  nerve.  It 
gives  off: — 


POPLITEAL    REGION.  541 

1,  two  or  more  considerable  branches  to  the  gluteus  maxim  us  j  2,  a 
coccygeal  branch,  which  runs  through  the  great  sacro-ischiatic  ligament, 
then  ramifies  in  the  gluteus  maximus,  and  on  the  back  of  the  coccyx ; 
3,  the  comes  nervi  ischiatici ;  4,  branches  to  the  several  external  rotator 
muscles ;  lastly,  branches  which  supply  the  upper  part  of  the  hamstring 
muscles ;  and  others  which  inosculate  with  the  internal  circumflex  and 
obturator  arteries  (p.  522). 

PUDIC  AETEBY          The  course  of  this  artery  and  nerve  has  been 
AND  NEEVB.  fuiiy  described  (p.  425).     Observe  now  that  they 

pass  over  the  spine  of  the  ischium,  accompanied  by  the  nerve  to  the 
obturator  internus,  and  that  in  a  thin  subject  it  is  possible  to  com- 
press the  artery  against  the  spine.  The  rule  for  finding  it  is  this  : 
rotate  the  foot  inwards,  and  draw  a  line  from  the  top  of  the  great 
trochanter  to  the  base  of  the  coccyx  ;  the  junction  of  the  inner 
with  the  outer  two-thirds  gives  the  situation  of  the  artery.* 

POPLITEAL  ^  *8  advisable  to  examine  the  popliteal  space 

SPACE.    ITS  at  this  stage  of  the  dissection,  in  order  that  the 

BOUNDAEIKS.  various  parts  may  be  carefully  made  out  with  as 

little  disturbance  as  possible  of  their  mutual  relations. 

A  vertical  incision  must  be  made  along  the  middle  of  the  ham, 
extending  from  six  inches  above,  to  three  inches  below  the  knee : 
transverse  incisions  should  be  made  at  each  extremity  of  the 
vertical,  so  that  the  skin  may  be  conveniently  reflected.  In  doing 
so,  care  must  be  taken  to  preserve  the  cutaneous  branch  of  the 
lesser  ischiatic  nerve,  which  descends  over  the  space  to  the  back  of 
the  leg. 

The  muscular  fascia  covering  the  space  is  very  strong,  and 
strengthened  by  numerous  transverse  fibres.  It  is  pierced  by 
the  posterior  saphena  vein,  which  passes  in  to  join  the  popliteal 
vein. 

The  fascia  having  been  reflected,  the  muscles  and  tendons  con- 
stituting the  boundaries  of  the  popliteal  space  are  to  be  cleaned. 
The  space  is  formed,  above,  by  the  divergence  of  the  hamstring 
muscles  to  reach  their  respective  insertions;  below,  by  the  con- 

*  MJ.  Travers  succeeded  in  arresting  haemorrhage  from  a  sloughing  ulcer  of  the 
glans  penis  by  pressing  the  pudic  artery  with  a  cork  against  the  spine  of  the  ischium. 


542  POPLITEAL   REGION. 

verging  heads  of  the  gastrocnemiiis :  its  shape  is  therefore  that 
of  a  lozenge.  It  extends,  above,  as  high  as  the  lower  third  of  the 
femur,  and,  below,  as  far  as  the  upper  sixth  of  the  tibia.  Above,  it 
is  bounded  on  the  inner  side  by  the  semitendinosus,  sernimem- 
branobus,  gracilis,  and  sartorius ;  on  the  outer  side,  by  the  biceps  ; 
below,  it  is  bounded  on  the  inner  side  by  the  internal  head  of  the 
gastrocnemius,  on  the  outer,  by  the  external  head  of  this  muscle 
and  the  plantaris. 

The  space  is  occupied  by  a  quantity  of  fat,  which  permits  the 
easy  flexion  of  the  knee ;  and  in  this  fat  are  found  the  popliteal 
vessels  and  nerves,  in  the  following  order : — nearest  to  the  surface 
are  the  nerves ;  the  artery  lies  close  to  the  bone,  the  vein  being 
superficial  to  the  artery  (fig.  125). 

GREAT  Along  the  outer  border  of  the  semimembranosus, 

ISCHIATIC  NERVE,  and  covered  by  the  long  head  of  the  biceps,  is  the 
great  ischiatic  nerve,  which,  after  giving  off  branches  to  the  three 
great  flexor  muscles,  divides,  about  the  lower  third  of  the  thigh 
(higher  or  lower  in  different  'subjects),  into  two  large  nerves — the 
peroneal  or  external  popliteal  and  the  internal  popliteal. 

The  peroneal  nerve  runs  close  by  the  inner  side  of  the  tendon 
of  the  biceps,*  and  subsequently  in  the  groove  between  this 
muscle  and  the  outer  head  of  the  gastrocnemius,  towards  the  head 
of  the  fibula.  As  it  passes  round  the  joint  it  gives  off  two  arti- 
cular branches  to  the  knee,  which  accompany  the  articular 
arteries,  and  a  recurrent  articular  branch,  which  runs  with  the 
recurrent  tibial  artery  to  the  front  of  the  knee.  It  supplies  also 
two  or  three  cutaneous  branches  to  the  posterior  and  outer  sur- 
faces of  the  leg. 

The  communicans  peronei  (fig.  125)  is  a  small  branch  given 
off  as  the  nerve  passes  over  the  gastrocnemius ;  it  joins  the  short 
saphenous  which  runs  down  the  back  of  the  calf,  and  behind  the 
outer  ankle,  to  supply  the  outer  side  of  the  foot  and  little  toe. 

Below  the  head  of  the  fibula  we  have  already  traced  the  divi 

*  The  nerve  is,  therefore,  very  liable  to  be  injured  in  the  operation  of  dividing  the 
outer  hamstring.  In  the  diagram,  the  nerve  is  not  near  enough  to  the  tendon,  their 
connections  having  been  severed. 


POPLITEAL    KEG1ON. 


543 


sion  of  the  peroneal  into  the  anterior  tibial,  and  the  musculo- 
cutaneous  nerves  (p.  532). 

The  internal  popliteal  nerve  accompanies  the  popliteal  artery, 
and,  at  the  lower  border  of  the  popliteus,  is  continued  under  the 
name  of  the  posterior  tibial.  The  nerve  in  the  popliteal  space  lies 


.  125. 


Semitendinosus. 

Semimembranosus. 

Gracili?. 

Sartorius. 


Inner  head  of  gastrocne- 
mius. 


LEFT   POPLITEAL   SPACE. 


superficial  to  and  rather  external  to  the  artery,  and  gives  off 
'muscular  branches  which  supply  the  gastrocnemius,  the  plantaris, 
the  soleus,  and  the  popliteus  ;  three  articular  branches,  two  accom- 
panying the  articular  arteries,  the  third  piercing  the  back  of  the 
capsule ;  and  the  short  saphenous,  which  descends  in  the  groove 
between  the  two  heads  of  the  gastrocnemius,  about  the  middle  of 


544  POPLITEAL    REGION. 

the  leg,  is  joined  by  the  communicans  peronei,  and  then,  running 
down  behind  the  outer  malleolus  in  company  with  the  short 
saphena  vein,  is  distributed  to  the  outer  side  of  the  little  toe. 
The  remainder  of  the  nerve,  as  posterior  tibial,  supplies  all  the 
flexor  muscles  on  the  back  of  the  leg  and  the  sole  of  the  foot. 

POPLITEAL  By  clearing  out  all  the  fat,  we  observe  that  the 

VESSELS.  popliteal  vessels  enter  the  ham  through  an  aperture 

in  the  adductor  magnus,  and  descend  close  to  the  back  part  of  the 
femur,  and  the  back  of  the  knee-joint.  At  first  they  are  partially 
overlapped  (in  muscular  subjects)  by  the  semimembranosus ;  indeed 
the  outer  border  of  this  muscle  is  a  good  guide  to  the  artery  in  the 
operation  of  tying  it.  The  popliteal  artery  lies  upon  the  triangular 
surface  at  the  back  of  the  lower  third  of  the  femur;  then,  upon  the 
ligamentum  posticum  Winslowii ;  and,  lastly,  upon  the  popliteus,  at 
the  lower  border  of  which  it  divides  into  the  anterior  and  posterior 
tibial.  Arising  at  right  angles  from  the  popliteal  artery  are  the  two 
superior  articular  arteries  ;  lower  down  are  two  inferior  articular 
arteries  ;  also  the  sural,  supplying  the  muscles  of  the  calf,  and  the 
azygos  artery ;  close  to  the  vessel  is  the  articular  branch  of  the 
obturator  nerve  which  supplies  the  knee-joint. 

The  popliteal  vein  lies  superficial  to  the  artery,  and  rather  to 
its  outer  side.  It  receives  the  short  saphena  vein.  Its  coats  are 
remarkably  thick,  and  on  transverse  section  resemble  those  of  an 
artery  of  a  similar  size. 

LYMPHATIC  Two  or  more  lymphatic  glands  are  situated  one 

GLANDS.  on  each  side  of  the  artery.    They  deserve  attention, 

because,  when  enlarged,  their  close  proximity  to  the  artery  may  com- 
municate a  pulsation  which  might  be  mistaken  for  an  aneurysm. 


DISSECTION   OF  THE  BACK   OF   THE   THIGH. 

The  incision  should  be  continued  along  the  remainder  of  the 
back  of  the  thigh,  and  the  skin  reflected. 

CUTANEOUS  ^he  s^m  a^  ^ne  ^ac^  °^  *ne  thigh  is  supplied  by 

NEBVES  AND  the  lesser  ischiatic  nerve,  which  runs  down  beneath 

VEINS,  the  fascia,  as  low  as  the  upper  third  of  the  calf, 


HAMSTRING    MUSCLES.  545 

distributing  branches  on  either  side.  On  the  outer  side  are  seen 
a  few  cutaneous  branches  from  the  posterior  division  of  the  ex- 
ternal cutaneous  nerve. 

The  subcutaneous  veins  at  the  back  of  the  thigh  are  very  small : 
here  they  would  be  liable  to  pressure.  But  near  the  popliteal 
space  there  is  a  vein,  called  the  short  saphena.  It  comes  up  the 
back  of  the  calf,  and  joins  the  popliteal  vein  after  perforating  the 
strong  fascia  covering  the  space. 

MUSCULAR  Respecting    this,    remark   that    its    fibres    run 

FASCIA,  chiefly  in  a  transverse  direction,  that  it  becomes 

stronger  as  it  passes  over  the  popliteal  space,  and  that  here  it  is 
connected  with  the  tendons  on  either  side.  Remove  it,  to  examine 
the  powerful  muscles  which  bend  the  leg,  called  the  hamstrings. 

HAMSTRING  There  are  three  of  these,  and  all  arise  by  strong 

MUSCLES.  tendons  from  the  tuber  ischii.     One,  the  biceps,  is 

inserted  into  the  head  of  the  fibula  ;  the  other  two — namely, 
the  semitendinosus  and  semimembranosus — are  inserted  into  the 
tibia.  The  divergence  of  these  muscles  towards  their  respective 
insertions  occasions  the  space  termed  the  popliteal,  which  is  occu- 
pied by  soft  fat,  the  popliteal  vessels,  nerves,  and  lymphatic 
glands. 

-o  This  muscle  has  two  origins,  a  long  and  a  short. 

The  long  head  arises,  by  a  strong  tendon,  from 
the  back  part  of  the  tuber  ischii  in  common  with  the  semi- 
tendinosus ;  the  short  head,  by  fleshy  fibres,  from  the  outer  lip  of 
the  linea  aspera  of  the  femur.  This  origin  begins  at  the  linea 
aspera,  just  below  the  insertion  of  the  gluteus  maximus,  and  con- 
tinues nearly  down  to  the  external  condyle.  It  joins  the  long 
head  of  the  muscle,  and  both  terminate  on  a  common  tendon, 
which  is  inserted  into  the  head  of  the  fibula,  by  two  portions 
separated  by  the  external  lateral  ligament  of  the  knee-joint.  It 
also  gives  off  a  strong  expansion  to  the  fascia  of  the  leg.  The 
tendon  covers  part  of  the  external  lateral  ligament  of  the  knee- 
joint,  and  a  small  bursa  intervenes. 

The  biceps  is  not  only  a  flexor  of  the  leg,  but  rotates  the  leg, 
when  bent,  outwards.  It  is  the  muscle  which  in  chronic  disease 

N  N 


546  HAMSTRING   MUSCLES. 

of  the  knee  dislocates  the  leg  outwards  and  backwards,  and 
at  the  same  time  rotates  it  outwards.  Each  head  of  the  biceps  is 
supplied  by  the  great  ischiatic  nerve.  The  short  head  is  some- 
times supplied  by  the  peroneal. 

SEMITEN-  This  arises,  in  common  with  the  biceps,  from 

DINOSUS.  the  back  part  of  the  tuber  ischii.     The  fibres  ter- 

minate upon  a  long  round  tendon,  which  rests  upon  the  semi- 
membranosus,  and  is  inserted  into  the  inner  surface  of  the  tibia 
by  an  expanded  tendon,  below  the  tendon  of  the  gracilis,  and 
behind  that  of  the  sartorius.  Like  them,  it  plays  over  the 
internal  lateral  ligament  of  the  knee,  and  is  provided  with  a  bursa. 
Its  nerve  comes  from  the  great  ischiatic. 

The  semitendinosus  sends  off  from  the  lower  border  of  its  ten  don 
a  very  strong  fascia  to  cover  the  leg,  which  is  attached  along  the 
inner  edge  of  the  tibia.  The  middle  of  the  muscle  is  intersected 
by  an  oblique  tendinous  line. 

SEMIMEM-  This  muscle  arises  from  the  tuber  ischii  above 

BRANOSUS.  an(j  external  to  the  two  preceding,  by  means  of  a 

strong  flat  tendon,  which  extends  nearly  half-way  down  the  thigh. 
This  tendon  descends  obliquely  under  the  biceps  and  semi- 
tendinosus, and  terminates  in  a  bulky  muscle,  which  lies  on  a 
deeper  plane,  and  more  internal,  than  the  others,  and  is  inserted 
by  a  thick  tendon  into  the  posterior  part  of  the  head  of  the  tibia. 
In  connection  with  the  insertion  of  this  tendon,  notice,  1 ,  that  it 
is  prolonged  under  the  internal  lateral  ligament  of  the  knee,  and 
that  a  bursa  intervenes  between  them  ;  2,  that  it  sends  a  strong 
prolongation  upwards  and  outwards  to  the  external  condyle  of  the 
femur,  forming  the  principal  portion  of  the  ligamentum  posticum 
Winslowii,  which  covers  the  back  of  the  knee-joint ;  3,  that 
a  dense  fascia  proceeds  from  its  lower  border,  and  binds  down  the 
popliteus ;  4,  that  it  is  intimately  connected  with  the  semilunar 
cartilages  of  the  joint,  so  as  to  keep  them  in  place  during  its 
movements.  Its  nerve  comes  from  the  great  ischiatic. 

A  large  bursa  is  almost  invariably  found  between  the  semi- 
membranosus  and  the  inner  head  of  the  gastrocnemius,  where 
they  rub  one  against  the  other.  It  is  generally  from  one  and  a 


HAMSTRING   MUSCLES. 


547 


FIG.  126. 


half  to  two  inches  long.  The  chief  point  of  interest  concerning 
it  is,  that  it  occasionally  communicates  with  the  synovial  mem- 
brane of  the  knee-joint,  not  directly,  but 
through  the  medium  of  another  bursa 
beneath  the  inner  head  of  the  gastro- 
cnemius.  From  an  examination  of  150 
bodies,  it  appears  that  this  communication 
exists  about  once  in  five  times ;  and  it 
need  scarcely  be  said  that  the  proportion 
is  large  enough  to  make  us  cautious  in 
interfering  with  this  bursa  when  it  be- 
comes enlarged.* 

ACTION  OF  THE         These  muscles  produce 
HAMSTRING  two  different  effects,  ac- 

MUSCLES.  cording    as    their    fixed 

point  is  at  the  pelvis  or  the  knee.  With 
the  fixed  point  at  the  pelvis,  they  bend 
the  knee ;  with  the  fixed  point  at  the 
knee,  they  take  a  very  important  part  in 
maintaining  the  body  erect.  For  instance, 
if,  when  standing,  the  body  be  bent  at  the 
hip  and  the  muscles  in  question  be  felt,  it 

will  be  found  that  they  are  in  strong  action,  to  prevent  the  trunk 
from  falling  forwards :  they,  too,  are  the  chief  agents  concerned  in 
bringing  the  body  back  again  to  the  erect  position.  In  doing  this, 
they  act  upon  a  lever  of  the  first  order,  as  shown  in  fig.  126 ;  the 
acetabulum  being  the  fulcrum  F,  the  trunk  w,  the  weight  to  be 
moved,  and  the  power  p,  at  the  tuber  ischii. 

To  put  the  action  of  the  muscles  of  the  thigh  on  the  pelvis  in 
the  clearest  point  of  view,  let  us  suppose  we  are  standing  upon  one 

*  When  the  bursa  in  question  becomes  enlarged,  it  occasions  a  fluctuating  swelling 
of  greater  or  less  dimensions  on  the  inner  side  of  the  popliteal  space.  The  swelling 
bulges  out,  and  becomes  tense  and  elastic  when  the  knee  is  extended,  and  vice  versa. 
As  to  its  shape,  it  is  generally  oblong ;  but  this  is  subject  to  variety,  for  we  know 
that  the  bursae,  when  enlarged,  are  apt  to  become  multilocular,  and  to  burrow  be- 
tween the  muscles  where  there  is  the  least  resistance. 

v  N  2 


548  HAMSTEING    MUSCLES. 

leg:  the  bones  of  the  lower  extremity  represent  a  pillar  which 
supports  the  weight  of  the  trunk  on  a  ball-and-socket  joint ;  the 
weight  is  nicely  balanced  on  all  sides,  and  prevented  from  falling 
by  four  groups  of  muscles.  In  front,  are  the  rectus  and  sartorius  ; 
on  the  inner  side,  the  adductors ;  on  the  outer  side,  the  gluteus 
medius  and  minimus ;  behind,  the  hamstrings  and  gluteus 
maximus. 

The  semimembranosus  can  also  rotate  the  knee  inwards,  thus 
assisting  the  popliteus. 

The  hamstring  muscles  are  supplied  with  blood  by  the  perfo- 
rating branches  of  the  profunda,  which  come  through  the  tendon 
of  the  adductor  magnus  close  to  the  femur.  Their  nerves  are 
derived  from  the  great  ischiatic. 

ISCHIATIC  This  nerve  descends   from  the  gluteal   region 

NERVE.  upon   the    adductor    magnus,    and,   after   being 

crossed  by  the  long  head  of  the  biceps,  runs  along  the  outer  border 
of  the  semimembranosus  down  the  popliteal  space.  The  further 
course  of  this  nerve  has  already  been  described  (p.  542). 

Deferring  the  course,  relations,  and  branches  of  the  popliteal 
artery  till  this  vessel  is  exposed  throughout  its  whole  course,  pass 
on  now  to  the  dissection  of  the  calf. 

Continue  the  incision  down  the  centre  of  the  calf  to  the  heel, 
and  reflect  the  skin. 

SHORT  OR  ^ne  large  vein  seen  m  the  middle  of  the  back 

POSTERIOR  SA-  of  the  leg  is  called  the  short  or  posterior  saphena. 
PHF.NA  VEIN.  it  commences  on  the  outer  side  of  the  foot,  ascends 

behind  the  outer  ankle,  where  it  has  a  communication  with  the 
deep  veins,  and  then  runs  up  the  calf  between  the  two  bellies  of 
the  gastrocnemius,  receiving  numerous  veins  in  its  course.  It 
eventually  passes  through  the  muscular  fascia,  and  joins  the 
popliteal  vein. 

The  chief  cutaneous  nerve  of  the  calf  is  the  short  or  posterior 
saphenous  nerve  ;  some  branches,  however,  from  the  long  saphenous 
and  lesser  ischiatic  nerves  are  to  be  traced,  ramifying  in  the  sub- 
cutaneous tissue  of  the  inner  and  upper  part  of  the  leg. 


MUSCLES    OF    THE    CALF.  549 


SHORT  OR  ^ne  s^or^  saphenous  nerve  *  is  derived  from 

POSTERIOR  SA-  the  popliteal  (fig.  125),  and  passes  down  between 
PHENOUS  NERVE.  the  two  heads  of  the  gastrocnemius  to  the  middle 
of  the  calf,  where  it  pierces  the  fascia.  Here  it  is  joined  by  a 
branch  from  the  peroneal  nerve  (communicans  peronei)  ;  it  then 
descends  with  the  short  saphena  vein,  and  is  finally  distributed  to 
the  outer  side  of  the  foot  and  the  little  toe. 

To  expose  the  muscles  of  the  calf,  reflect  the  muscular  fascia 
by  incisions  corresponding  to  those  made  through  the  skin. 

MUSCLES  OF  The  great  flexor  muscle  of  the  foot  consists  of 

THE  CALF.  two  portions  :  the  superficial  one,  called  the  gas- 

trocnemius, arises  from  the  lower  end  of  the  femur;  the  deep 
one,  called  the  soleus,  arises  from  the  tibia  and  fibula.  The 
force  of  both  is  concentrated  on  one  thick  tendon,  called  the 
tendo  Achillis,  which  is  inserted  into  the  os  calcis. 

GASTRO-  This  muscle  arises  by   two   strong    tendinous 

CNEMIUS.  heads,  one  from  the  upper  and  back  part  of  each 

condyle  of  the  femur  (fig.  125).  The  inner  head  is  the  larger  and 
longer.  The  two  parts  of  the  muscle  descend,  distinct  from  each 
other,  and  form  the  two  bellies  of  the  calf,  of  which  the  inner  is 
mther  the  lower.  Both  terminate,  rather  below  the  middle  of  the 
leg,  on  the  broad  commencement  of  the  tendo  Achillis. 

The  gastrocnemius  should  be  divided  transversely  near  its 
insertion,  and  reflected  upwards  from  the  subjacent  soleus,  as  high 
as  its  origin.  By  this  proceeding  you  observe  that  the  contiguous 
surfaces  of  the  muscles  are  covered  by  a  glistening  tendon,  which 
receives  the  insertion  of  their  fibres,  and  transmits  their  collected 
force  to  the  tendo  Achillis. 

Observe  also  the  large  sural  vessels  and  nerves  (branches  of  the 
popliteal)  which  enter  the  mesial  aspect  of  each  head  of  the  muscle. 
To  facilitate  the  play  of  the  inner  tendon  over  the  condyle,  there 
is  a  bursa,  which  generally  communicates  with  the  knee-joint  ;  arid 
in  the  substance  of  the  outer  tendon  is  commonly  found  a  small 

*  This  nerve  is  sometimes  called  the  communicans  poplitei,  and  does  not  take  the 
name  of  short  saphenous  till  its  junction  with  the  communicans  peronei.     (P.  542.) 


550  MUSCLES   OP   THE    CALF. 

piece  of  fibro-cartilage.  Lastly,  between  the  gastrocnemius  and 
soleus  is  the  tendon  of  the  plantaris. 

This  small  muscle  *  arises  from  the  rough  line 
just  above  the  outer  condyle  of  the  femur  and 
from  the  posterior  ligament  of  the  knee-joint.  It  descends  close 
to  the  inner  side  of  the  outer  head  of  the  gastrocnemius,  and 
terminates,  a  little  below  the  knee,  in  a  long  tendon,  which  can  be 
traced  down  the  inner  border  of  the  tendo  Achillis  to  the  calca- 
neum.  Its  nerve  comes  from  the  internal  popliteal. 

This  muscle  arises  from  the  head  and  upper 
SOLEUS, 

third  of  the  posterior  surface  of  the  fibula,  from 

the  oblique  ridge  on  the  back  of  the  tibia,f  from  about  the  middle 
third  of  the  inner  border  of  this  bone,  and  from  an  aponeurotic 
arch  thrown  over  the  posterior  tibial  vessels.  The  muscular  fibres 
bulge  out  beyond  the  gastrocnemius,  and  terminate  on  a  broad 
tendon,  which,  gradually  contracting,  forms  a  constituent  part  of  the 
tendo  Achillis.  The  muscle  lies  upon  the  flexor  longus  digitorum, 
the  tibialis  posticus,  the  flexor  longus  pollicis,  and  the  posterior 
tibial  vessels  and  nerve.  The  soleus  is  supplied  with  blood  by  several 
branches  from  the  posterior  tibial ;  also  by  a  large  branch  from 
the  peroneal.  Its  nerve  comes  from  the  internal  popliteal  and 
enters  the  top  of  the  muscle.  This  is  an  important  muscle  in  a 
surgical  point  of  view,  for  two  reasons — 1,  by  reflecting  its  tibial 
origin,  we  can  reach  the  posterior  tibial  artery  ;  2,  by  reflecting 
its  fibular  origin  we  can  reach  the  peroneal. 

The  tendo  Achillis  begins  about  the  middle  of  the  leg,  and  is 
at  first  of  considerable  breadth,  but  it  gradually  contracts  and 
becomes  thicker  as  it  descends.  The  narrowest  part  of  it  is  about 
one  inch  and  a  half  above  the  heel;  here,  therefore,  it  can  be  most 
conveniently  and  safely  divided  for  the  relief  of  club-foot.  There 

*  This  is  the  representative  of  the  palmaris  longus  of  the  forearm.  In  man  it  is 
lost  on  the  calcaneum,  but  in  monkeys,  who  have  prehensile  feet,  it  is  the  proper 
tensor  muscle  of  the  plantar  fascia.  It  is  remarkably  strong  in  bears  and  plantigrade 
mammals. 

f  The  tibial  and  fibular  origins  of  the  soleus  constitute  what  some  anatomists 
describe  as  the  two  heads  of  the  muscle.  Between  them  descend  the  popliteal  vessels, 
protected  by  a  tendinous  arch. 


POPLITEAL    VESSELS. 


FIG.  127. 


is  no  risk  of  injuring  the  deeper-seated  parts,  because  they  are 
separated  from  the  tendon  by  a  quantity  of  fat.  Its  insertion 
is  into  the  under  and  back  part  of  the  tuberosity  of  the  os  calcis. 
The  tendon  previously  expands  a  little  :  between  it  and  the  bone 
is  a  bursa  of  considerable  size. 

The  action  of  the  gastrocnemius  and  soleus  is  to  raise  the  body 
on  the  toes.  Since  the  gastrocnemius  passes  over  two  joints,  it 
has  the  power  (like  the  rectus)  of  extending  the  one  while  it  bends 
the  other,  and  it  is,  therefore,  admirably  adapted  to  the  purpose  of 
walking.  For  instance,  by  first  extending  the  foot  it  raises  the 
body,  and  then,  by  bending  the  knee,  it  transmits  the  Aveight  from 
one  leg  to  the  other.  Supposing  the  fixed  point  to  be  at  the  heel, 
the  gastrocnemius  is  also  concerned  in  keeping  the  body  erect,  for 
it  keeps  the  tibia  and  fibula  perpendicular  on  the  foot,  and  thus 
counteracts  the  tendency  of  the  body  to  fall  forwards. 

The  tendo  Achillis,  in  pointing  the  toes,  acts  upon  a  lever  of 
the  first  order.  The  fulcrum  is  at 
the  ankle-joint,  F  (fig.  127);  the  re- 
sistance, w,  at  the  toes ;  the  power  at 
the  heel,  F.  All  the  conditions  are 
those  of  a  lever  of  the  first  order. 
The  power  and  the  weight  act  in  the 
same  direction  on  opposite  sides  of 
the  fulcrum.  In  raising  the  body  on 
tiptoe,  the  tendo  Achillis  acts  on  a 
lever  of  the  second  order ;  the  fulcrum 
being  then  at  the  ball  of  the  great  toe,  and  the  weight  of  the  body 
at  the  ankle. 

After  passing  through  the  opening  in  the  tendon 
of  the  adductor  magnus,  the  femoral  artery  takes 
the  name  of  popliteal.  It  descends  nearly  per- 
pendicularly behind  the  knee-joint,  between  the 
origins  of  the  gastrocnemius,  as  far  as  the  lower  border  of  the 
popliteus,  where  it  divides  into  the  anterior  and  posterior  tibial. 
In  its  descent  it  lies,  first,  upon  the  lower  part  of  the  femur,  and 
here  it  is  slightly  overlapped  by  the  semimembranosus ;  next,  it 


COUBSE  AND 
REI^TIOXS  OF  THE 
POPLITEAL 
AETEBY. 


552  POPLITEAL    VESSELS. 

lies  upon  the  posterior  ligament  of  the  knee-joint,  and,  lastly, 
upon  the  popliteus.  At  its  lower  part  the  artery  is  covered  by  the 
gastrocnemius  and  is  crossed  by  the  plantaris.  The  vein  closely 
accompanies  the  artery,  and  is  situated  superficially  with  regard  to 
it,  and  rather  to  its  outer  side  in  the  first  part  of  its  course.  The 
internal  popliteal  nerve  runs  also  in  a  similar  direction  with  the 
vein,  but  is  still  more  superficial  and  to  the  outer  side  (fig.  125). 
The  vessels  and  the  nerve  are  surrounded  by  fat,  and  one  or  two 
lymphatic  glands  are  generally  found  in  the  immediate  neighbour- 
hood of  the  artery,  just  above  the  joint. 

The  branches  of  the  popliteal  artery  are  the  articular  and  the 
sural. 

There  are  five  articular  branches  for  the  supply  of  the  knee-joint  and 
the  articular  ends  of  the  bone  :  the  two  superior — external  and  internal — 
run,  one  above  each  condyle,  close  to  the  bone ;  the  two  inferior — exter- 
nal and  internal — run  below  the  joint. 

1.  The  superior  external  articular  artery  runs  above  the  external 
condyle,   passes    beneath   the   biceps,    and   through   the  intermuscular 
septum  :  it  then  divides  into  a  siiperficial  and  a  deep  branch  •  the  super- 
ficial supplies  the  vastxis  externus,  and  then  forms  part  of  the  patellar 
arterial  plexus ;  the  deep  branch  keeps  close  to  the  femur  and  supplies 
the  joint. 

2.  The  superior  internal  articular  artery  runs  above  the  internal 
condyle,  under  the  tendon  of  the  adductor  magnus  and  vastus  internus, 
and  divides  into  two  branches,  a  superficial  and  a  deep,  which  take  a 
corresponding  course  to  those  on  the  outer  side. 

3.  The  inferior  external  articular  artery  runs  under  the  gastrocne- 
mius, over  the  popliteus,  then,  passing  beneath   the    external  lateral 
ligament  and  the  tendon  of  the  biceps,  it  reaches  the  patella,  where  it 
breaks  up  into  branches  anastomosing  with  the  other  articular  arteries. 

4.  The  inferior  internal  articular  artery  runs  between  the  tuberosity 
of  the  tibia  and  the  internal  lateral  ligament,  and  supplies  the  inner  and 
anterior  part  of  the  joint. 

5.  The   azygos   artery   is  given   off    from   the  deep   aspect   of  the 
popliteal,  pierces  the  ligamentum  posticum  Winslowii,  to  supply  the 
crucial  ligaments  and  the  synovial  membrane. 

The  several  articular  arteries  form  over  the  front  and  sides  of  tbe  joint 
a  network  of  vessels  which  anastomose,  superiorly,  with  the  descending 


POPLITEAL    VESSELS.  553 

branch  of  the  external  circumflex  and  the  anastomotica  magna  ;  inferiorly, 
with  the  anterior  tibial  recurrent ;  and  also  among  themselves.  It  is 
mainly  through  these  channels  that  the  collateral  circulation  is  established 
in  the  leg  after  ligature  of  the  superficial  femoral. 

The  sural  arteries  proceed  one  to  each  head  of  the  gastrocnemius, 
and  are  proportionate  in  size  to  the  muscle ;  one  or  two  branches  are 
distributed  to  the  soleus.  These  arteries  are  accompanied  by  branches 
of  the  internal  popliteal  nerve  for  the  supply  of  the  muscle. 

Small  superior  muscular  branches  supply  the  vasti  and  hamstring 
muscles,  and  inosculate  with  the  perforating  and  articular  arteries. 

POPLITEAL  This  vein  is  formed   by   the  junction   of  the 

VEIN.  vense  comites  of  the  anterior  and  posterior  tibial 

arteries,  and  is  situated  superficial  to  the  artery.  It  crosses  ob- 
liquely from  the  inner  to  the  outer  side  of  the  artery,  and  is  con- 
tinued upwards  as  the  femoral.  It  receives  in  the  popliteal  space 
the  short  saphena,  the  articular,  and  sural  veins. 

The  insertion  of  the  tendon  of  the  semimembranosus  into  the 
head  of  the  tibia,  and  its  several  connections,  described  (p.  546), 
should  now  be  fully  examined. 

p  This  muscle  arises  within  the  capsule  of  the 

knee-joint,  from  a  depression  on  the  outside  of  the 
external  condyle  by  a  thick  tendon,  which  runs  beneath  the  ex- 
ternal lateral  ligament.  The  muscular  fibres  gradually  spread  out, 
and  are  inserted  into  the  triangular  surface  of  the  tibia  above  the 
soleal  ridge  on  the  bone.  It  is  supplied  by  a  branch  of  the  popliteal 
nerve  which  enters  its  deep  surface.  Its  action  is  to  flex  the  leg, 
and  then  to  rotate  the  tibia  inwards.  The  tendon  plays  over  the 
articulation  between  the  tibia  and  fibula ;  and  a  bursa  intervenes, 
which  generally  communicates  by  a  wide  opening  with  the  knee- 
joint.  The  tendinous  origin  is  in  contact  with  the  external  semi- 
lunar  cartilage. 

Keflect  the  soleus  from  its  origin,  and  remove  it  from  the  deep- 
seated  muscles,  observing  at  the  same  time  the  numerous  arteries 
which  enter  its  under  surface.  This  done,  notice  the  fascia  which 
binds  down  the  deep  muscles.  It  is  attached  to  the  margin  of  the 
bones  on  either  side,  increases  in  strength  towards  the  ankle,  and 


554       DEEP  MUSCLES  AT  THE  BACK  OF  THE  LEG. 

forms  a  posterior  annular  ligament  which  confines  the '  tendons 
and  the  vessels  and  nerves  in  their  passage  into  the  sole  of  the  foot. 

DEEP  MUSCLES  There  are  three  : — the  flexor  longtis  digitorum 
ON  THE  BACK  OF  on  the  tibial  side ;  the  flexor  longus  pollicis  on 
THE  LEG.  y^  fibula^ ;  the  tibialis  posticus  upon  the  inter- 

osseous  membrane,  between  and  beneath  them  both. 

FlJ5XOR  This  arises  from  the  posterior  surface  of  the 

LONGUS  DIGI-  tibia,  commencing  below  the  popliteus,  and  ex- 

TORTTM.  tending  to  within  four  inches  of  the  lower  end  of 

the  bone,  also  from  the  fascia  over  the  tibialis  posticus.  The  fibres 
terminate  on  a  tendon  which  runs  through  a  groove  behind  the 
inner  ankle,  and,  entering  the  sole,  divides  into  four  tendons,  which 
are  inserted  into  the  ungual  phalanges  of  the  four  outer  toes.  It 
is  supplied  by  the  posterior  tibial  nerve. 

FLEXOB  This  powerful  muscle  arises  from  the  lower  two- 

LONGUS  POLLICIS.  thirds  of  the  posterior  surface  of  the  fibula,  from 
the  septum  between  it  and  the  peronei,  and  from  the  aponeurosis 
over  the  tibialis  posticus.  The  fibres  terminate  on  a  tendon  which 
runs  through  a  groove  on  the  back  of  the  astragalus ;  thence  it 
passes  under  the  sustentaculum  tali,  and  is  inserted  into  the 
ungual  phalanx  of  the  great  toe.  The  chief  action  of  this  muscle 
is  to  raise  the  body  on  the  tip  of  the  great  toe.  It  is  essential 
to  the  propulsion  of  the  body  in  walking.  It  is  supplied  by  the 
posterior  tibial  nerve. 

TIBIALIS  This  is  so  concealed  between  the  two  preceding 

POSTICUS.  muscles  that  it  cannot  be  properly  examined  with- 

out reflecting  them.  It  arises  from  the  interosseous  membrane, 
from  the  opposite  surfaces  of  the  tibia  and  fibula  for  about  their 
middle  three-fifths,  and  from  the  aponeurosis  covering  it.  In  the 
lower  part  of  the  leg  it  passes  between  the  tibia  and  the  flexor 
longus  digitorum.  Its  muscular  fibres  terminate  on  a  tendon 
which  comes  into  view  a  short  distance  above  the  inner  ankle,  and, 
running  through  the  same  groove  with  the  tendon  of  the  flexor 
longus  digitorum,  enters  the  sole,  and  is  inserted  into  the  scaphoid 
and  internal  cuneiform  bones,  and  by  fibrous  prolongations  into 
most  of  the  tarsal  and  metatarsal  bones.  Its  action  is  to  bend 


POSTERIOR    TIBIAL    ARTERY.  555 

and  turn  the  foot  inwards.  It  is  supplied  by  the  posterior  tibial 
nerve.  The  precise  situation  of  the  tendon  of  the  tibialis  posticus 
is  interesting,  surgically,  because  the  tendon  has  to  be  divided 
for  the  relief  of  talipes  varus.  It  lies  close  to,  and  parallel  with, 
the  inner  edge  of  the  tibia,  so  that  this  is  the  guide  to  it.  It 
is  necessary  to  relax  the  tendon,  while  the  knife  is  introduced 
between  the  tendon  and  the  bone.  Its  synovial  sheath  commences 
about  1^  inches  above  the  end  of  the  internal  malleolus,  and  is 
consequently  opened  in  the  operation. 

Attention  should  now  be  directed  to  the  internal  or  posterior 
annular  ligament,  which  binds  down  the  tendons  behind  the 
inner  ankle. 

It  is  attached  to  the  internal  malleolus  and  the  inner  border  of 
the  os  calcis.  It  is  continuous  above  with  the  deep  fascia,  below 
with  the  plantar  fascia.  Beneath  it  pass  the  tendons  of  the  deep- 
seated  muscles  of  the  leg  into  the  sole  of  the  foot.  The  ^elative 
positions  of  the  structures  passing  under  this  ligament,  proceeding 
from  within  outwards,  are — the  tendons  of  the  tibialis  posticus, 
and  the  flexor  longus  digitorum ;  the  posterior  tibial  artery  ac- 
companied by  its  venae  comites  ;  the  posterior  tibial  nerve  ;  and, 
lastly,  the  tendon  of  the  flexor  longus  pollicis. 

COUBSE  AND  This  artery  is  one  of  the  branches  into  which 

KELATIONS  OF  the  popliteal  divides  at  the  lower  border  of  the 
THE  POSTEBIOB  popHtcus.  It  descends  over  the  deep  muscles  at 
TIBIAI.  ABTEBT.  thg  back  of  the  leg  ^  ^  interval  between  the 

internal  malleolus  and  the  os  calcis,  and,  entering  the  sole,  divides 
beneath  the  abductor  pollicis  into  the  external  and  internal  plantar 
arteries.  It  lies,  first,  for  a  short  distance,  upon  the  tibialis 
posticus,  then,  on  the  flexor  longus  digitorum ;  but  behind  the 
ankle  it  is  in  contact  with  the  tibia,  so  that  here  it  can  be  felt 
beating,  and  effectually  compressed.  In  the  upper  part  of  its 
course,  it  runs  nearly  midway  between  the  bones,  and  is  covered 
by  the  gastrocnemius  and  soleus  :  to  tie  it,  therefore,  in  this 
situation,  is  difficult.  But  in  the  lower  part  of  its  course, 
it  gradually  approaches  the  inner  border  of  the  tibia,  from 
which,  generally  speaking,  it  is  not  more  than  ^  or  f  of  an  inch 


556  POSTERIOR   TIBIAL   ARTERY. 

distant.  Here,  being  comparatively  superficial,  it  may  easily  be 
tied.  Immediately  bebind  the  internal  malleolus,  it  lies  between 
tbe  tendons  of  the  flexor  longus  digitorum  on  the  inner  side,  and 
the  flexor  longus  pollicis  on  the  outer.  It  has  two  venae  comites, 
which  communicate  at  intervals.  The  posterior  tibial  nerve  which 
accompanies  the  artery  is  at  first  on  its  inner  side,  then  crosses 
over  it,  and  for  the  greater  part  of  its  course  lies  external  to  the 
artery.  Its  branches  are  as  follows  : — 

a.  Numerous  muscular  branches  to  the  soleus  and  the  deep  muscles. 

b.  The  peroneal  is  a  branch   of  considerable  size ;  often  as  large  as 
the  posterior  tibial.     Arising  about  an  inch  below  the  division  of  the 
popliteal,  it  descends  close  to  the  inner  side  of  the  fibula,  and  then  over 
the  articulation  between  the  tibia  and  fibula  to  the  outer  part  of  the  os 
calcis,  where  it  inosculates  with  the  malleolar  and  plantar  arteries.     All 
down  the  leg  it  is  embedded  among  the  muscles :  being  covered,  first, 
by  tbe  soleus,  afterwards  by  the  flexor  longus  pollicis.     To  both  these 
muscles,  to  tbe  latter  especially,  it  sends  numerous  branches,  and  just 
above  the  ankle  it  gives  off  a  constant  one — the  anterior  peroneal — which 
passes  through  the  interosseous  membrane  to  tbe  under  aspect  of  tbe 
peroneus  tertius,  then  runs  in  front  of  the  tibio-fibular  articulation, 
and  inosculates    with   the  other   malleolar   and   tarsal   arteries.      The 
peroneal  supplies  tbe  nutrient  artery  of  the  fibula,  and,  about  an  inch 
above  the  os  calcis,  sends  off  a  transverse  communicating  branch,  which 
inosculates  with  the  posterior  tibial  artery  under  the  tendon  of  the  flexor 
longus  pollicis. 

c.  The  nutrient  artery  of  the  tibia. 

POSTERIOR  This   is    the  continuation  of  the  popliteal.     It 

TIBIAL  NERVE.  descends  close  to  its  corresponding  artery,  and, 
behind  the  inner  ankle,  divides  into  the  external  and  internal 
plantar  nerves.  In  the  first  part  of  its  course  the  nerve  lies  super- 
ficial to  the  artery,  and  rather  to  its  inner  side  ;  but  lower  down 
the  nerve  crosses  the  artery,  and  passes  to  its  outer  side.  It  sup- 
plies branches  to  the  three  deep-seated  muscles,  and  a  cutaneous 
branch —  calcaneo-plantar — to  the  sole  of  the  foot, 


557 


DISSECTION   OF  THE   SOLE   OF  THE   FOOT. 

Make  a  perpendicular  incision  down  the  middle 
.DISSECTION 

of  the   sole,   and   reflect   the    skin.      Notice   the 

peculiar  structure  of  the  subcutaneous  tissue.  It  is  composed  of 
globular  masses  of  fat,  separated  by  strong  fibrous  septa,  and  forms 
elastic  pads,  especially  marked  at  the  heel,  and  at  the  ball  of  the 
great  and  the  little  toes ;  these  being  the  points  which  form  the 
tripod  supporting  the  arch  of  the  foot. 

In  removing  the  subcutaneous  tissue  from  the  ball  of  the  great 
and  the  little  toes,  we  often  meet  with  bursae,  simple  or  multilocular. 
They  are  generally  placed  between  the  skin  and  the  sesamoid  bones, 
and  have  remarkably  thick  walls.  Frequently  an  artery  an\i  nerve 
can  be  traced  running  directly  through  one  of  these  sacs,  wi  ich 
explains  the  acute  pain  produced  by  their  inflammation. 

CUTANEOUS  The  skin  of  the  heel  is  supplied  by  the  calcaneo- 

NERVES.  plantar  branch  of  the  posterior  tibial  nerve  ;  the 

remainder  of  the  sole  by  small  branches  of  the  plantar  nerves 
which  come  through  the  fascia,  as  in  the  palm  of  the  hand. 

PIANTAR  This  is  a  remarkably  dense  white  and  glistening 

FASCIA.  fascia.     It  extends  from  the  under  and  back  part 

of  the  os  calcis  to  the  distal  extremities  of  the  metatarsal  bones. 
It  is  divided  into  a  strong  central  and  two  lateral  less  dense  por- 
tions ;  from  which  prolongations  pass  deeply  inwards,  separating 
the  lateral  from  the  central  muscles.  The  middle  portion,  cover- 
ing the  flexor  brevis  digitorum,  is  narrow  behind,  and,  as  it  passes 
forwards  towards  the  toes,  is  spread  out,  and  strengthened  by  trans- 
verse fibrous  bands.  The  inner  portion  is  comparatively  thin,  and 
surrounds  the  abductor  pollicis,  becoming  continuous  posteriorly 
with  the  internal  annular  ligament.  The  outer  portion  is  thicker 
than  the  inner,  especially  as  it  passes  forwards  to  be  attached  to 
the  proximal  end  of  the  fifth  metatarsal  bone.  It  covers  the 
abductor  minimi  digiti. 

Near  the  distal  ends  of  the  metatarsal  bones,  the  central  part 


558  SOLE    OF   THE   FOOT. 

divides  into  five  portions ;  each  of  these  subdivides  into  two  slips, 
which  embrace  the  corresponding  flexor  tendons,  and  are  attached 
to  the  metatarsal  bones  and  their  connecting  ligaments.  Between 
the  primary  divisions  of  the  fascia — that  is,  in  a  line  between  the 
toes — are  seen  the  digital  vessels  and  nerves.  This  arrangement  is 
in  all  respects  like  that  in  the  palm. 

In  the  interdigital  folds  of  the  skin,  there  are  also  ligamentous 
fibres,  which  run  from  one  side  of  the  foot  to  the  other,  and  answer 
the  same  purpose  as  those  in  the  hand  (p.  298). 

The  plantar  fascia  must  be  partially  removed  to  examine  the 
muscles.  Towards  the  os  calcis  its  removal  is  not  accomplished 
without  some  difficulty,  since  the  muscles  arise  from  it. 

SUPERFICIAL  After  the  removal  of  the  fascia  three  muscles 

MUSCLES.  are  exposed.     All  arise  from  the  os  calcis  and  the 

fascia,  and  proceed  forwards  to  the  toes.*  The  central  one  is  the 
flexor  brevis  digitorum,  the  two  lateral  are  the  abductor  pollicis, 
and  the  abductor  minimi  digiti. 

ABDUCTOB  This  muscle  arises  from  the  inner  and  back  part 

POLLICIS.  of  the  os  calcis,  from  the  plantar  fascia,  and  from 

the  internal  annular  ligament.  Its  origin  arches  over  the  plantar 
vessels  and  nerves  in  their  passage  to  the  sole.  The  fibres  run 
along  the  inner  side  of  the  sole,  and  terminate  on  a  tendon  which 
is  inserted  into  the  inner  side  of  the  base  of  the  first  phalanx  of 
the  great  toe,  through  the  medium  of  the  internal  sesamoid  bone. 
Its  nerve  comes  from  the  internal  plantar. 

ABDUCTOB  This  muscle  has  a  very  strong  origin  from  the 

MINIMI  DIGITI.  under  surface  of  the  os  calcis,  from  its  external 
tubercle,  from  the  plantar  fascia,  and  from  the  external  inter- 
muscular  septum.  Some  of  its  fibres  terminate  on  a  tendon 
which  is  inserted  into  the  proximal  end  of  the  metatarsal  bone  of 
the  little  toe ;  but  the  greater  part  runs  on  to  a  tendon  which  is 
inserted  into  the  outer  side  of  the  first  phalanx  of  the  little  toe. 
It  is  supplied  by  the  external  plantar  nerve. 


*  They  are  separated  from  each  other  by  strong  perpendicular  partitions — inter- 
muscular  septa — which  pass  in  from  the  plantar  fascia. 


SOLE    OF    THE    FOOT. 


559 


FLEXOR  EHEVIS         This  muscle  arises  from  the  under  surface  of 
DIGITORUM.  the  os  calcis,  between  the  two  preceding,  from  the 

plantar  fascia  and  the  intermuscular  septa.  It  passes  forwards 
and  divides  into  four  tendons,  which  run  superficial  to  those  of 
the  long  flexor.  Cut  open  the  sheath  which  contains  them  ;  follow 
them  on  to  the  toes,  to  see  that  each  bifurcates  over  the  first 
phalanx,  to  allow  the  long  tendon  to  pass  through ;  then  the  two 
slips,  reuniting,  are  inserted  into  the  sides  of  the  second  phalanx. 

FIG.  128. 


1.  Abductor     mi- 

nimi digiti. 

2.  Flexor  accesso- 

rius. 

3.  Abductor  pollicis 

4.  External  plantar 

artery     aud 
nerve. 

5.  Tendon  of  flexor 

longus  pollicis. 

6.  Internal  plantar 

artery     and 
nerve. 

7.  Flexor      longus 

digitorum. 


8.  Flexot-     brevis 

minirm  tl'giti. 

9.  Lumbricald  . 

10.'  Internal  r7.an- 
tar  nerve. 

11.  Tendons  of  the 
flexor  brevis 
digitorum  bi- 
furcating, for 
the  passage  of 
the  tendons  of 
the  flexor  lon- 
gus digitorum. 


MUSCLES,    VESSELS,    AND    NERVES    OF    THE    SOLE   OF    THE   RIGHT    FOOT,    AFTER 
REFLECTION    OF   THE   FLEXOR   BREVIS   DIGITORUM. 

The  same  arrangement  prevails  in  the  fingers.     It  is  supplied  by 
the  internal  plantar  nerve. 

The  three  superficial  muscles  should  now  be  reflected,  by  saw- 
ing off  about  half  an  inch  of  the  os  calcis,  and  then  turning  it 
downwards  with  the  muscles  attached  to  it.  This  done,  we  bring 
into  view  the  plantar  vessels  and  nerves,  the  second  layer  of 
muscles — i.e.  the  long  flexor  tendon  of  the  great  toe,  that  of  the 
other  toes,  and  the  flexor  accessorius. 


560  SOLE    OF   THE    FOOT. 

TENDON  OF  THE  Tracing  this  tendon  into  the  sole,  you  find  that 

FLEXOR  Loxous  an  accessory  muscle  is  attached  to  it.     The  flexor 

DIGITORUM.  accessorius  arises  by  muscular   fibres   from  the 

MUSCULUS  Ac-  inner  gide  of  the  og  caicis   and  ky  tendinous  fibres 

CESSORIUS.  ' 

from  the  outer  side  in  front  of  the  external  tuber- 
cle. Its  fibres  run  straight  forwards,  and  are  inserted  into  the 
fibular  side  of  the  upper  surface  of  the  tendon,  so  that  their  action 
is  not  only  to  assist  in  bending  the  toes,  but  to  make  the  common 
tendon  pull  in  a  straight  line  towards  the  heel ;  which  from  its 
oblique  direction,  it  could  not  do  without  the  accessory  muscle. 
The  common  tendon  then  divides  into  four,  one  for  each  of  the  four 
outer  toes.  These  run  in  the  same  sheath  with  the  short  tendons, 
and,  after  passing  through  their  divisions,  are  inserted  into  the  bases 
of  the  ungual  phalanges.  Eespecting  the  manner  in  which  the  ten- 
dons are  confined  by  fibrous  sheaths,  and  lubricated  by  a  synovial  lin- 
ing, what  was  said  of  the  fingers  (p.  304)  applies  equally  to  the  toes. 
The  flexor  accessorius  is  supplied  by  the  external  plantar  nerve. 

These  four  little  muscles  are  placed   between 

the  long  flexor  tendons.  Each,  excepting  the  most 
internal,  arises  from  the  adjacent  sides  of  two  tendons,  proceeds 
forwards,  and  then,  sinking  between  the  toes,  terminates  in  an 
aponeurosis  which  passes  round  the  inner  side  of  the  four  outer 
toes,  and  joins  the  extensor  tendon  on  the  dorsum  of  the  first 
phalanges  of  the  toes.  Concerning  their  use,  refer  to  p.  306.  The 
two  outer  lumbricales  are  supplied  by  the  external  plantar  nerve, 
the  two  inner  by  the  internal. 

Now  trace  the  long  flexor  tendon  of  the  great  toe.  From  the 
groove  in  the  astragalus  it  runs  along  the  groove  in  the  lesser 
tuberosity  of  the  os  caicis,  above,  that  is  nearer  to  the  bones  than 
the  tendon  of  the  flexor  longus  digitorum,  and  then  straight  to 
the  base  of  the  last  phalanx.  It  crosses  the  long  flexor  tendon  of 
the  toes,  and  the  two  tendons  are  connected  by  an  oblique  slip  ; 
so  that  we  cannot  bend  the  other  toes  without  the  great  toe. 

PLANTAR  The  posterior  tibial  artery,  having  entered  the 

ARTERIES.  sole  between  the  origins  of  the  abductor  pollicis, 

divides  into  the  external  and  internal  plantar  arteries. 


SOLE    OF    THE    FOOT. 


561 


FIG.  129. 


The  internal  plantar  artery  is  very  small :  it  passes  forwards 
between  the  abductor  pollicis  and  the  flexor  brevis  digitorum  to 
the  base  of  the  great  toe,  and  then  is  continued  along  the  inner 
side  of  that  toe,  where  it  terminates  in  small  inosculations  with 
the  digital  arteries.  Its  chief  use  is  to  supply  the  muscles  between 
which  it  runs. 

The  external  plantar  is  the  principal  artery  of  the  sole,  and 
alone  forms  the  plantar  arch  (fig.  129).  It 
runs  obliquely  outwards  across  the  sole  to- 
wards the  base  of  the  fifth  metatarsal  bone  ; 
then,  sinking  deeply,  it  bends  inwards  across 
the  bases  of  the  metatarsal  bones,  and  inos- 
culates with  the  dorsalis  pedis  in  the  first 
interosseous  space.  At  first  it  lies  between 
the  os  calcis  and  the  abductor  pollicis ;  it 
then  passes  between  the  flexor  brevis  digi- 
torum and  the  flexor  accessorius  ;  and,  lastly, 
it  lies  deep  beneath  the  flexor  tendons,  and 
the  adductor  pollicis,  close  to  the  metatarsal 
bones.  Deeply  seated  as  it  appears  to  be,  that 
part  of  its  curve  near  the  fifth  metatarsal 
bone  lies  immediately  beneath  the  fascia. 

The  external  plantar  sends  a  branch  to 
the  skin  of  the  heel,  and  another  round  the 
outer  edge  of  the  foot ;  but  its  chief  branches 
are  the  four  digital  arteries,  which  arise 
in  the  deepest  part  of  its  course.  They 
supply  both  sides  of  the  fifth,  fourth,  third, 
and  the  outer  side  of  the  second  toe ;  the  great  toe,  and  the  inside 
of  the  second,  being  supplied  by  the  dorsalis  hallucis.  Concerning 
the  ultimate  distribution  of  the  digital  arteries,  refer  to  the  ac- 
count given  of  these  arteries  in  the  hand  (p.  300). 

Besides  the  digital  arteries,  the  arch  gives  off  three  small 
branches  — the  perforating — which  ascend  between  the  three  outer 
interosseous  spaces,  and  inosculate  with  the  dorsal  interosseous 
arteries  at  each  end  of  the  spaces. 

0  O 


1.  Internal  plantar  artery. 

2.  External  do. 


562  SOLE    OF   THE    FOOT. 

PLANTAR  The   posterior   tibial   nerve   divides,   like  the 

NERVES,  artery,  into  an  external  and  internal  plantar.     The 

internal  plantar  is  the  larger,  and  supplies  nerves  to  the  three 
inner  toes  and  a  half,  like  the  median  in  the  palm.  It  also  sup- 
plies the  muscles  on  the  inner  side  of  the  sole,  the  abductor 
pollicis,  the  flexor  brevis  pollicis,  the  flexor  brevis  digitorum, 
and  the  two  inner  lumbricales;  also  articular  branches  to  the 
tarsus  and  metatarsus.  The  external  plantar  nerve  sends  branches 
to  the  flexor  accessorius  and  the  abductor  minimi  digiti,  and  then 
divides  into  a  superficial  and  deep  branch.  The  superficial 
branch  supplies  the  fifth  toe  and  the  outer  side  of  the  fourth  toe 
(like  the  ulnar  nerve  in  the  palm),  and  the  flexor  brevis  minimi 
digiti.  The  deep  branch  accompanies  the  plantar  arch,  and  fur- 
nishes nerves  to  the  two  outer  lumbricales,  the  adductor  pollicis, 
the  transversalis  pedis,  and  all  the  interossei. 

THIRD  LAYEE  Having  traced  the  principal  vessels  and  nerves, 

OF  MUSCLES.  divide  them  with  the  flexor  tendons  near  the  os 

calcis,  and  turn  them  down  toward  the  toes,  to  expose  the 
deep  muscles  in  the  sole.  These  are,  the  flexor  brevis  and  ad- 
ductor pollicis,  the  flexor  brevis  minimi  digiti,  and  the  transver- 
salis pedis. 

FLEXOB  BREVIS         This  muscle  arises  by  a  flat  tendon  from  the 
POLLICIS.  cuboid  bone,  and  from  the  fibrous  prolongation  of 

the  tibialis  posticus  into  the  external  cuneiform.  It  proceeds 
along  the  metatarsal  bone  of  the  great  toe,  and  divides  into  two 
portions,  which  run  one  on  each  side  of  the  long  flexor  tendon, 
and  are  inserted  by  tendons  into  the  sides  of  the  first  phalanx  of 
the  great  toe.  The  inner  tendon  is  inseparably  connected  with 
the  abductor  pollicis,  the  outer  with  the  adductor  pollicis.  In 
each  tendon  there  is  a  sesamoid  bone.  These  bones  not  only 
increase  the  strength  of  the  muscle,  but,  both  together,  form  a 
pulley  for  the  free  play  of  the  long  flexor  tendon  ;  so  that  in  walk- 
ing the  tendon  is  not  pressed  upon.  Its  nerve  comes  from  the 
internal  plantar. 

ADDUCTOR  This    very   powerful   muscle   arises    from   the 

POLLICIS.  bases  of  the  third  and  fourth  metatarsal  bones, 


SOLE    OF    THE    FOOT.  563 

and  from  the  sheath  of  the  peroneus  longus.  Passing  obliquely 
forwards  and  inwards  across  the  foot,  it  is  inserted  through  the 
external  sesamoid  bone  into  the  outer  side  of  the  base  of  the  first 
phalanx  of  the  great  toe  together  with  the  inner  head  of  the 
flexor  brevis.  This  muscle  greatly  contributes  to  support  the 
arch  of  the  foot.  Like  the  adductor  of  the  thumb  it  should  be 
considered  as  an  interosseous  muscle.  Its  nerve  is  derived  from 
the  external  plantar. 

FLEXOR  BREVIS  This  little  muscle  arises  from  the  base  of  the 
MINIMI  Diem.  "  fifth  metatarsal  bone  and  the  sheath  of  the  pero- 
neus longus,  proceeds  forward  along  the  bone,  and  is  inserted  into 
the  base  of  the  first  phalanx  of  the  little  toe.  It  is  supplied  by 
the  external  plantar  nerve. 

TRANSVEBSAUS  This  slender  muscle  runs  transversely  across 
PEDIS.  the  distal  ends  of  the  metatarsal  bones.  It  arises 

by  little  fleshy  slips  -from  the  bases  of  the  four  outer  toes,  and  is 
inserted  into  the  first  phalanx  of  the  great  toe  with  the  adductor 
pollicis,  of  which  it  ought  to  be  considered  a  part.  Its  nerve 
comes  from  the  external  plantar. 

The  fourth  layer  of  muscles  consists  of  the  interossei. 

These  muscles  are  arranged  nearly  like  those  in 
the  hand.  They  occupy  the  intervals  between  the 
metatarsal  bones,  and  are  seven  in  number,  four  being  on  the 
dorsal  aspect  of  the  foot,  three  on  the  plantar.  The  four  dorsal 
interossei  arise  each  by  two  heads  from  the  contiguous  sides  of 
the  metatarsal  bones,  and  are  inserted  into  the  bases  of  the  first 
phalanges.  The  first  is  inserted  into  the  inner  side  of  the  second 
toe  ;  the  remaining  three  into  the  outer  sides  of  the  second,  third, 
and  fourth.  The  plantar  interossei,  three  in  number,  arise  from 
the  inner  sides  and  under  surfaces  of  the  third,  fourth,  and  fifth 
metatarsal  bones,  and  are  inserted  respectively  into  the  inner 
sides  of  the  bases  of  the  first  phalanges  of  the  third,  fourth,  and 
fifth  toes. 

The  use  of  the  interosseous  muscles  is  to  draw  the  toes  to  or 
from  each  other,  and  they  do  the  one  or  the  other  according  to  the 
side  of  the  phalanx  on  which  they  act.  Now,  if  we  draw  a  lorgi- 

o  o  2 


564  LIGAMENTS   OF    THE    PELVIS. 

tudinal  line  through  the  second  toe,  we  find  that  all  the  dorsal 
muscles  draw  from  that  line,  and  the  plantar  towards  it.  This 
is  the  key  to  the  action  of  them  all.  A  more  detailed  account 
of  these  muscles  is  given  in  the  dissection  of  the  hand  (p.  336). 
Between  the  tendons  of  the  interossei,  that  is,  between  the  distal 
ends  of  the  metatarsal  bones,  there  are  bursae  which  facilitate 
movement.  They  sometimes  become  enlarged  and  occasion  painful 
swellings  between  the  roots  of  the  toes.  The  flexor  brevis  minimi 
digiti,  the  tran-sversalis  pedis,  and  all  the  interossei  are  supplied 
by  the  external  plantar  nerve. 

Now  trace  the  tendons  of  the  peroneus  longus  and  tibialis 
posticus.  The  tendon  of  the  peroneus  longus  is  the  deepest  in 
the  sole.  It  runs  through  a  groove  in  the  cuboid  bone  obliquely 
across  the  sole  towards  its  insertion  into  the  outer  side  of  the  base 
of  the  metatarsal  bone  of  the  great  toe.  It  is  confined  in  a 
strong  fibrous  sheath,  lined  throughout  by  synovial  membrane. 

The  tendon  of  the  tibialis  posticus  may  be  traced  over  the 
internal  lateral  ligament  of  the  ankle,  and  thence  under  the  head 
of  the  astragalus  to  the  scaphoid  bone,  into  which  it  is  chiefly 
inserted.  Prolongations  are  sent  off  to  the  cuneiform  bones,  to 
the  cuboid,  to  the  sustentaculum  tali,  and  to  the  bases  of  the 
second,  third,  and  fourth  metatarsal  bones.  Observe  that  the 
tendon  contributes  to  support  the  head  of  the  astragalus,  and 
that  for  this  purpose  it  often  contains  a  sesamoid  bone.  This 
is  one  of  the  many  provisions  for  the  solidity  of  the  arch  of 
the  foot. 

DISSECTION   OF   THE   LIGAMENTS. 

LIGAMENTS  OF  The  sacrum  is  united  to  the  last  lumbar  ver- 

THEPBLTIS.  tebra  in  the  same  manner  as  one  vertebra  is  to 

another.  The  same  observation  applies  to  the  union  between  the 
sacrum  and  the  coccyx.  The  student  should,  therefore,  refer  to 
the  description  of  the  ligaments  of  the  spine  (p.  246). 

The  innominate  bones  are  connected  to  each  other  in  front, 
constituting  the  symphysis  pubis  ;  posteriorly  to  the  sacrum,  con- 
stituting the  sacro-iliac  symphysis. 


LIGAMENTS    OP    THE    PELVIS. 


565 


PDBIC  STM-  This  is  secured   by,   1,  an  anterior   ligament, 

PHYSIS.  consisting  of  irregular  superficial  fibres  which  run 

obliquely,  and  of  deep  fibres  which  pass  transversely ;  2r  a  pos- 
terior ligament,  less  distinct ;  3,  a  sub-pubic  ligament :  it  is 
very  strong,  and  rounds  off  the  point  of  the  pubic  arch  ;  4,  a 
superior  ligament  which  passes-  across  the  upper  surface  of  the 
pubic  bones  ;  5,  an  intermediate  fibro- cartilage.  A  perpendicular 
section  through  it  shows  that  it  consists-  of  concentric  layers,  and 
that  its  general  structure  resembles  that  between  the  bodies  of  the 
vertebrae.  In  the  upper  and  back  part  of  this  fibro-cartilage  is  a 

FIG.  130. 


Great  sacro-ischiatic  ligament 
Lesser  sacro-ischiatic  ligiment 


Ilio-femoral  or  accessory  liga- 
ment of  the  hip-joint. 


smooth  cavity  lined  with  epithelium.  The  cartilage  acts  like  a 
buffer,  and  breaks  the  force  of  shocks  passing  through  the  pelvic 
arch. 

The  ilium  is  connected  with  the  fifth  lumbar  vertebra  by  the 
ilio-lumbar  ligament.  It  is  very  strong,  and  extends  from  the 
transverse  process  of  the  last  lumbar  vertebra  to  the  crest  of  the 
ilium  (fig.  131). 

SACRO-ILIAC  This   is   secured   by,    1,  an  anterior  ligament 

SYMPHYSIS.  which  consists  of  ligamentous  fibres   passing  in 

front ;  2,  a  posterior  ligament,  composed  of  fibres  much  stronger 


566  LIGAMENTS    OF   THE    HIP-JOINT. 

and  more  marked,  which  pass  behind  the  articulation.  A  well- 
marked  fasciculus  of  fibres  passes  from  the  posterior  superior  spine 
to  the  third  segment  of  the  sacrum,  and  is  called  the  oblique  sacro- 
iliac  ligament.  The  anterior  part  of  the  bones  forming  this 
articulation  is  crusted  with  articular  cartilage,  of  which  the  shape 
is  like  that  of  the  ear.  Behind  this  is  the  strong  interosseous 
ligament,  which  contributes  powerfully  to  the  security  of  the 
joint. 

SACEO-ISCHIATIC  These  are  two  strong  ligaments  passing  from 
LIGAMENTS.  the  sacrum  to  the  ischium.  The  great  sacro- 

ischiatic  is  triangular,  and  extends  from  the  posterior  inferior 
spine  of  the  ilium,  and  the  side  of  the  sacrum  and  coccyx,  to  the 
tuberosity  of  the  ischium.  The  lesser  sacro-ischiatic  ligament 
passes  from  the  sacrum  and  coccyx  to  the  spine  of  the  ischium, 
where  it  narrows  considerably.  It  lies  anterior  to  the  preceding 
ligament.  These  two  ligaments  not  only  connect  the  bones,  but 
also,  from  their  great  breadth,  contribute  to  diminish  the  lower 
aperture  of  the  pelvis. 

LIGAMENTS  OF  This  joint  is  secured  by  the  form  of  the  bones, 

THE  HIP-JOINT.  and  by  the  strength  of  the  powerful  muscles  which 
surround  it.  Although  a  perfect  ball-and-socket  joint,  its  motion 
is  somewhat  limited  :  the  disposition  of  its  ligaments  restricts  its 
range  of  motion  to  those  directions  only  which  are  most  consistent 
with  the  maintenance  of  the  erect  attitude,  and  the  requirements 
of  this  part  of  the  skeleton. 

CAPSULAR  The  capsular  ligament  is  attached  above  to 

LIGAMENT.  the  circumference  of  the  acetabulum,  a  little 

external  to  the  margin,  and  also  to  the  transverse  ligament ; 
below,  to  the  inter-trochanteric  ridge  of  the  femur  in  front,  and  to 
the  middle  of  the  neck  behind.  The  capsule  is  rendered  exceed- 
ingly thick  and  strong  in  front  by  a  broad  ligament,  ilio-femoral, 
which  extends  from  the  anterior  inferior  iliac  spine,  and  then 
divides  like  the  two  arms  of  the  inverted. letter  jr^,  one,  the  inner, 
passes  to  the  lesser  trochanter,  the  outer,  to  the  upper  part  of  the 
anterior  inter-trochanteric  ridge.  This  ligament  is  very  strong, 


LIGAMENTS    OF    THE    HIP-JOINT. 


567 


serves  as  a  strap  to  prevent  the  femur  being  extended  beyond  a 
certain  point,  and  limits  rotation  inwards  and  outwards. 
Open  the  capsule  to  as-  FIO_ 

certain  its  great  thickness  in 
front,  and  its  strong  attach- 
ment to  the  bones.  This 
exposes  the  cotyloid  liga- 
ment, and  the  ligamentum 
teres. 

LlGAMENTUX  Tll6       Hga- 

TEHES.  mentum  teres 

is  exposed  by  drawing  the  head 
of  the  femur  out  of  the  socket. 
This  ligament  is  somewhat 
flat  and  triangular.  Its  base,  / 
which  is  bifid,  is  attached,  be-  \ 
low,  to  the  borders  of  the  notch 
in  the  acetabulum ;  its  apex, 
to  the  fossa  in  the  head  of 
the  femur.  To  prevent  pres- 
sure on  it,  and  to  allow  free 
room  for  its  play,  there  is  a 
gap  at  the  bottom  of  the  acetabulum.  This  gap  is  not  crusted 
with  cartilage  like  the  rest  of  the  socket,  but  is  occupied  by  soft 
fat.  The  ligamentum  teres  is  surrounded  by  the  synovial  mem- 
brane. An  artery  runs  up  with  it  to  the  head  of  the  femur.  It 
is  a  branch  of  the  obturator,  and  enters  the  acetabulum  through 
the  notch  at  the  lower  part. 

The  chief  use  of  the  ligamentum  teres  is  to  assist  in  steadying 
the  pelvis  on  the  thigh  in  the  erect  position.  In  this  position,  the 
ligament  is  vertical,  and  quite  tight  (fig.  131):  it  therefore  prevents 
the  pelvis  from  rolling  towards  the  opposite  side,  or  the  thigh  from 
being  adducted  beyond  a  certain  point.  Another  purpose  served 
by  this  ligament  is  to  limit  rotation  of  the  thigh,  both  inwards 
and  outwards. 


VERTICAL    SECTION    THROUGH    THE    HIP. 


568  LIGAMENTS    OP    THE    KNEE-JOINT. 

COTYLOID  The  cotyloid  ligament  is  a  piece  of  fibro-cartilage 

LIGAMENT.  -  which  is  attached  all  round  the  margin  of  the  ace- 

tabulum.  Its  circumference  is  thicker  than  its  free  margin,  which 
shelves -off ;  thus  it  not  only  deepens  the  cavity,  but  embraces  the 
head  of  the  femur  like  a  sucker.  It  extends  over  the  notch  at  the 
lower  part  of  the  acetabulum,  and  in  this  situation  has  received 
the  name  of  the  transverse  ligament. 

The  ligaments  of  the  hip  are  so  arranged  that,  when  we  stand 
'  at  ease,'  the  pelvis  is  spontaneously  thrown  into  a  position  in  which 
its  range  of  motion  is  the  most  restricted ;  for  the  accessory  liga- 
ment (ilio-femoral)  of  the  capsule  prevents  it  from  rolling  back- 
wards, and  the  ligamentum  teres  prevents  its  rolling  towards  the 
opposite  side.  This  arrangement  economises  muscular  force  in 
balancing  the  trunk. 

The  synovial  membrane  extends  down  to  the  base  of  the  neck 
of  the  femur  in  front,  but  only  two-thirds  down  behind.  It  is  laid 
upon  a  thick  periosteum. 

The  atmospheric  pressure  is,  of  itself,  sufficient  to  keep  the  limb 
suspended  from  the  pelvis,  supposing  all  muscles  and  ligaments 
to  be  divided.  When  fluid  is  effused  into  the  hip-joint,  the  bones 
are  no  longer  maintained  in  accurate  contact ;  and  it  sometimes 
happens  that  the  head  of  the  femur  escapes  from  its  cavity,  giving 
rise  to  a  spontaneous  dislocation. 

LIGAMENTS  OF  The  knee  is  a  hinge-joint,  and,  looking  at  the 

THE  KNEE-JOINT.  skeleton,  one  would  suppose  that  it  was  very 
insecure.  But  this  insecurity  is  only  apparent ;  the  joint  being 
surrounded  by  powerful  ligaments,  and  a  thick  capsule  formed  by 
the  tendons  of  the  muscles  which  act  upon  it. 

First  examine  the  tendons  concerned  in  the  protection  of 
the  knee-joint.  In  front  is  the  ligamentum  patellae;  on  either 
side  are  the  tendons  of  the  vasti ;  at  the  back  of  the  joint  are  four 
tendons — namely,  the  tendons  of  the  gastrocnemius,  the  tendon  of 
the  semimembranosus,  and  of  the  popliteus.  It  deserves  to  be 
noticed  that  the  weakest  part  of  the  joint  is  near  the  tendon  of  the 
popliteus  :  here,  therefore,  pus  formed  in  the  popliteal  space  may 
make  its  way  into  the  joint,  or  vice  versa. 


LIGAMENTS    OF    THE    KNEE-JOINT. 


569 


The  proper  ligaments  of  the  joint  are — 1,  the  lateral',  2,  the 
crucial  in  the  interior. 

INTERNAL  This  is  a  broad  flat  band,  which  extends  from 

LATERAL  LIGA-         the  inner  condyle  of  the  femur  to  the  inner  side 
MENT-  of  the  tibia,  a  little  below  its  head  (fig.  132).     A 

few  of  the  deeper  fibres  are  attached  to  the  inner  semi-lunar  carti- 
lage, and  serve  to  keep  it  in  place.  The  inferior  internal  articular 
artery,  and  part  of  the  tendon  of  the  semimembranosus,  pass  under- 
neath this  ligament.  In  the  several  motions  of  the  joint,  there 
FIG.  132.  is  a  certain  amount  of  friction  between 

the  ligament  and  the  head  of  the  tibia, 
and  consequently  a  small  bursa  is  in- 
terposed. 

EXTERNAL  LA-  This      IS     a     strong 

TERAL  LIGAMENT.  round  band,  which  ex- 
tends from  the  outer  condyle  of  the 
femur  to  the  head  of  the  fibula.  This 
ligament  separates  the  two  divisions  of 
the  tendinous  insertion  of  the  biceps. 
Posterior  to,  and  running  parallel  with, 
the  external  lateral  ligament  is  a 
smaller  band  of  fibres,  called  the  shwt 
external  lateral  ligament. 

POSTERIOR  This,  which  is  gene- 

LIGAMENT.  rally  called  '  ligamen- 

tumposticum  WinslowiiJ  consists  of 
expansions  derived  from  the  tendons  at 
the  back  of  the  joint,  chiefly,  however, 
from  the  semimembranosus  (p.  546). 
It  extends  from  the  posterior  part  of  the  tuberosity  of  the  tibia  to 
the  outer  condyle  of  the  femur.  It  not  only  closes  and  protects  the 
joint  behind,  but  prevents  its  extension  beyond  the  perpendicular. 
The  joint  should  be  opened  above  the  patella.  Observe  the 
great  extent  of  the  fold  which  the  synovial  membrane  forms  above 
this  bone.*  It  allows  the  free  play  of  the  bone  over  the  lower  part 

*  In  performing  operations  near  the  knee,  the  joint  should  always  be  bent,  in 
order  to  draw  the  synovial  fold  as  much  as  possible  out  of  the  way. 


DIAGRAM   OF   THE    SEMI-LUNAR 
CARTILAGES    AND    LATERAL    LI- 
GAMENTS   OF   THE    KNEE. 

1.  Internal  lateral  ligament. 

2.  External  ditto. 


570  LIGAMENTS    OF    THE    KNEE-JOINT. 

of  the  femur.  The  fold  extends  higher  above  the  inner  than  the 
outer  condyle,  which  accounts  for  the  form  of  the  swelling  produced 
by  effusion  into  the  joint. 

FOLDS  OF  Below  the  patella  a  slender  band  of  the  sy  no  vial 

SYNOVIAL  MEM-  membrane  proceeds  backwards  to  the  space  between 
BRANE.  the  condyles,  and  is  called  the  ligamentum  mu- 

cosum.  Two  similar  horizontal  folds  are  termed  the  ligamenta 
alaria.  These  are  not  true  ligaments,  but  merely  remnants  of  the 
partition  which,  in  the  early  stage  of  the  joint's  growth,  divided 
it  into  two  halves. 

Outside  the  synovial  membrane  there  is  always  fat ;  especially 
under  the  ligamentum  patellae.  Its  use  is  to  fill  up  vacuities,  and 
to  mould  itself  to  the  several  movements  of  the  joint. 

CRUCIAL  The  crucial  ligaments,  so  named  because  they 

LIGAMENTS.  cross  like  the  letter  X,  extend  from  the  mesial 

side  of  each  condyle  to  the  head  of  the  tibia.  The  anterior  or 
external,  the  smaller,  ascends  from  the  inner  part  of  the  fossa  in 
front  of  the  spine  of  the  tibia,  backwards  and  outwards  to  the 
inner  and  back  part  of  the  external  condyle.  The  posterior  or 
internal,  best  seen  from  behind,  extends  from  the  back  of  the 
fossa  behind  the  spine  of  the  tibia  forwards  to  the  front  of  the 
inner  condyle. 

Between  the  condvles  and  the  articular  surfaces 

INTER-ARTI-  <  J 

CULAR  OR  of  the   tibia  are  two  incomplete  rings  of  fibro- 

SEMI-LUNAR  cartilage,  shaped  like  the  letter  C.     They  serve 

CARTILAGES.  ^0  deepen  the  articular  surfaces  of  the  tibia  ;  their 

mobility  and  flexibility  enable  them  to  adapt  themselves  to  the 
condyles  in  the  several  movements  of  the  joint ;  they  distribute 
pressure  over  a  greater  surface  and  break  shocks.  They  are 
thickest  at  the  circumference,  and  gradually  shelve  off  to  a  thin 
margin :  thus  they  fit  in  between  the  bones,  and  adapt  a  convex 
surface  to  a  flat  one,  as  shown  in  fig.  132.  Their  form  is  suited  to 
the  condyles,  the  inner  being  oval,  the  outer  circular,  and  the 
synovial  membrane  covers  both  surfaces  of  the  cartilages.  The 
ends  of  each  are  firmly  attached  by  ligaments  to  the  pits  in  front 
and  behind  the  spine  of  the  tibia  ;  but  the  ends  of  the  external  one 


LIGAMENTS   OP   THE    KNEE-JOINT.  571 

lie  within  those  of  the  internal  which  are  attached  further  from  the 
spine.  The  cartilages  are  connected  in  front  by  a  thin  transverse 
ligament ;  and  their  circumference  is  attached  round  the  head  of 
the  tibia  by  fibrous  tissue,  called  the  coronary  ligament  (seen  in 
fig.  132),  yet  not  so  closely  as  to  restrict  their  range  of  motion.* 

ACTION  OF  THE          Their  respective  points   of  attachment  are  such 
LIGAMENTS.  that,  when  the  joint  is  extended,  all  the  ligaments 

are  tight,  to  prevent  extension  beyond  the  perpendicular;  thus 
muscular  force  is    economised.     But  when  the  joint  is  bent  the 
ligaments  are  relaxed,  enough  to  admit  a  slight  rotatory  movement 
of  the  tibia.     This  movement  is  more  free  outwards  than  inwards  ; 
and  is  effected,  not  by  rotation  of  the  tibia  on  its  own 
axis,  but  by  rotation  of  the  outer  head  round  the  inner.     FlG>  133- 
Rotation  outwards  is  produced  by  the  biceps  ;  rotation 
inwards  by  the  popliteus  and  semimembranosus. 

The  crucial  ligaments,  though  placed  inside  the  joint, 
answer  the  same  purposes  as  the  eoronoid  process  and 
the  olecranon  of  the  elbow.     They  make  the  tibia  slide 
properly   forwards   and  backwards.     In   extension,   the 
anterior  crucial  ligament  is  tight ;  in  flexion,  the  posterior 
ligament  becomes  tight  and  consequently  limits  flexion.     CRUCIAL 
They  also  conjointly  limit  excessive  rotation.     They  not  LIGAMENTS 
only  prevent  dislocation  in  front  or  behind,  but  they     OFTHB 
prevent  lateral  displacement,  since  they  cross  each  other 
like  braces,  as  shown  in  fig.  133. 

SUPERIOR  There  is  a  joint  between  the  tibia  and  fibula  at 

TIBIO-FIBULAR  their  upper  and  lower  extremities.  The  upper 
JOINT>  joint  is  secured  by  an  anterior  and  a  posterior 

tibio-fibular  ligament;  their  fibres  are  very  strong  and  run  in 
an  oblique  direction  downwards  and  outwards,  passing  from  the 
external  tuberosity  of  the  tibia  to  the  head  of  the  fibula.  The 

*  Of  the  two  cartilages  the  external  has  the  greater  freedom  of  motion,  because  in 
rotation  of  the  knee  the  outer  side  of  the  tibia  moves  more  than  the  inner.  Conse- 
quently, it  is  not  in  any  way  connected  to  the  external  lateral  ligament ;  so  far  from 
this,  it  is  separated  from  it  by  the  tendon  of  the  popliteus,  of  which  the  play  is  facili- 
tated by  a  bursa  communicating  freely  with  the  joint.  For  this  reason  the  external 
cartilage  is  more  liable  to  dislocation  than  the  internal. 


572  LIGAMENTS   OF   THE    ANKLE-JOINT. 

contiguous  surfaces  of  the  bones  are  crusted  with  cartilage.  In  the 
large  majority  of  instances  the  synovial  membrane  is  a  separate 
one,  but  it  occasionally  communicates  with  the  synovial  membrane 
of  the  knee-joint. 

INTEROSSEOUS  The  contiguous  borders  of  the  tibia  and  fibula 

MEMBRANE.  are  connected  by  the  interosseous  membrane.  The 

purpose  of  it  is  to  afford  additional  surface  for  the  attachment 
of  muscles.  Its  fibres  pass  chiefly  downwards  and  outwards  from 
the  tibia  to  the  fibula,  but  a  few  fibres  cross  like  the  letter  X. 
The  anterior  tibial  artery  comes  forwards  above  the  interosseous 
membrane,  through  an  oval  space  about  an  inch  below  the  head 
of  the  fibula.  Lower  down  there  is  an  aperture  for  the  anterior 
peroneal  artery.  It  is  moreover  pierced  here  and  there  by  small 
blood-vessels. 

INFERIOR  The  lower  extremities  of  the  tibia  and  fibula 

TIBIOFIBVLAR  are  firmly  connected,  for  it  is  essential  to  the 
security  of  the  ankle-joint  that  there  should  be 
little  or  no  movement  between  the  two  bones.  The  anterior 
ligament  is  composed  of  oblique  fibres  which  pass  downwards  from 
the  tibia  to  the  fibula;  the  posterior  ligament  is  stronger  and 
narrower  than  the  anterior,  and  its  fibres  pass  horizontally  from 
the  outer  malleolus  to  the  posterior  border  of  the  tibia,  above 
the  articular  surface.  The  inferior  interosseous  ligament  connects 
the  contiguous  surfaces  of  the  two  bones.  The  synovial  membrane 
of  this  joint  is  an  extension  upwards  of  that  of  the  ankle- 
joint. 

LIGAMENTS  OF  From  the  form  of  the  bones,  it  is  obvious 

THE  ANKLE-JOINT.  £ha,t  the  ankle  is  a  hinge-joint ;  consequently, 
its  security  depends  upon  the  great  strength  of  its  lateral  liga- 
ments. The  hinge,  however,  is  not  so  perfect  but  that  it  ad- 
mits of  a  slight  rotatory  motion,  of  which  the  centre  is  on 
the  fibular  side,  and  therefore  the  reverse  of  that  in  the  case 
of  the  knee. 

INTERNAL  This  ligament,  sometimes  called,  from  its  shape, 

LATERAL  deltoid,  is  exceedingly  thick  and  strong,  and 

LIGAMENT.  compensates  for  the  comparative  shortness  of  the 


LIGAMENTS    OP    THE    ANKLE-JOINT.  573 

malleolus  on  this  side  (fig.  134).  The  great  strength  of  it  is  proved 
by  the  fact  that,  in  dislocations  of  the  ankle  inwards,  the  summit 
of  the  malleolus  is  more  often  broken  off  than  the  ligament  torn. 
It  extends  from  a  deep  excavation  at  the  apex  of  the  malleolus, 
radiates  from  this  point,  and  is  attached  to  the  side  of  the 
astragalus,  also  to  the  os  calcis,  to  the  scaphoid  bone,  and  to  the 
inferior  calcaneo-scaphoid  ligament,  which  it  firmly  braces  up 
(fig.  134). 

EXTERNAL  This  ligament  consists  of  three  distinct  fasciculi 

LATERAL  — an  anterior,  a  posterior,  and  a  middle  (fig.  1 35). 

LIGAMENT.  ^11  three  arise  from  surfaces  near  the  summit  of 

FIG.  134. 


1.  Plantar  fascia. 

2.  Calcaneo-scaphoid  ligament  which  supports  the  head  of  the  astragalus. 

3.  Internal  lateral  ligament,  called  from  its  shape  deltoid. 

the  external  malleolus ;  the  first  two  are  inserted  into  the  front  and 
the  back  of  the  astragalus  respectively ;  the  middle  into  the  outer 
surface  of  the  os  calcis. 

ANTERIOR  AND          The  closure  of  the  joint  is  completed,  in  front 
POSTERIOR  and  behind,  by  an  anterior  and  a  posterior  liga- 

LIGAMENTS.  ment  attached  to  the  bones  near  their  articular 

surfaces,  and  sufficiently  loose  to  permit  the  necessary  range  of 
motion. 

Besides   flexion  and  extension,   the   ankle-joint  admits   of  a 


574 


LIGAMENTS    OF    THE    TAKSAL    JOINTS. 


slight  lateral  movement,  only  permitted  in   the  extended   state, 
FIG.  135.  for  the  better  direction  of  our  steps. 

In  adaptation  to  this  movement  the 
internal  malleolus  is  shorter  than  the 
outer ;  it  is  not  so  tightly  confined  by 
its  ligaments,  and  its  articular  surface 
is  part  of  a  cylinder. 

Open  the  joint  to  see  that  the 
breadth  of  the  articular  surfaces  of  the 
bones  is  greater  in  front  than  behind. 
The  object  of  this  is  to  render  the 
astragalus  less  liable  to  be  dislocated 
backwards.  Whenever  this  happens,  the 
astragalus  must  of  necessity  become 
firmly  locked  between  the  malleoli. 

LIGAMENTS  The  astragalus  is  the 

CONNECTING  THE  key-stone  of  the  arch  of 
BONES  OF  THE  the  foot,  and  supports 
FooT-  the  whole  weight  of  the 

body.  It  articulates  with  the  os  calcis 
and  the  os  scaphoides  in  such  a  manner  as  to  permit  the  abduction 
and  adduction  of  the  foot,  so  useful  in  the  direction  of  our  steps. 

ASTRAGALO-  The  astragalus  articulates  with  the  os  calcis,  by 

CALCANEAL  LiGA-  two  distinct  surfaces  separated  by  the  interosseous 
MENTS-  groove,  of  which  the  anterior  is  convex,  the 

posterior  slightly  concave.  The  interosseous  ligament  descends 
vertically  in  the  interosseous  canal,  and  is  the  principal  bond 
of  union  between  the  two  bones.  The  posterior  ligament  is  a 
short  oblique  band,  which  passes  from  the  posterior  border  of  the 
astragalus  to  the  upper  border  of  the  os  calcis.  The  external 
ligament  passes  vertically  from  the  astragalus  to  the  os  calcis. 

ASTEAGALO-  The  anterior  surface  of  the  astragalus  is  broadly 

SCAPHOID  LIQA-  convex,  fitting  into  the  concave  surface  of  the 
MENT>  scaphoid.  Superiorly,  the  surfaces  of  the  two 

bones  are  connected  by  a  broad  ligament,  astragalo-scaphoid, 
which  blends  with  the  external  calcaneo-scaphoid. 


DIAGRAM    OF  THE   EXTERNAL 
LATERAL   LIGAMENT. 

1.  Anterior  part. 

2.  Posterior  part. 

3.  Middle  part. 

4.  Interosseous  ligament  between 

the  astragalus  and  os  calcis. 


LIGAMENTS    OP    THE    TARSAL  JOINTS. 


575 


CALCANEO- 
SCAPHOID  LIGA- 
MENT. 


FIG.  136. 


In  the  skeleton  the  head  of  the  astragalus 
articulates  in  front  with  the  scaphoid,  but  the 
lower  part  of  it  is  unsupported.  This  interval  is 
bridged  over  by  a  very  strong  and  slightly  elastic  ligament,  which 
extends  from  the  os  calcis  to  the  scaphoid  (fig.  1 34).  These  bones, 
together  with  the  ligament,  form  a  complete  socket  for  the  head 
of  the  astragalus ;  it  is  this  joint,  chiefly,  which  permits  the 
abduction  and  adduction  of  the  foot.  The  ligament  being  slightly 
elastic,  allows  the  keystone  of  the  arch  (the  astragalus)  a  play, 
which  is  of  great  service  in  preventing  concussion  of  the  body. 
Whenever  this  ligament  yields,  the  head  of  the  astragalus  falls, 
and  the  individual  becomes  gradually  flat-footed. 

The  ligament  is  thick  and  strong,  and  passes  horizontally  for- 
wards from  the  sustentaculum  tali  to  the  plantar  surface  of  the 
scaphoid,  where  it  is  connected  with  the  tendon 
of  the  tibialis  posticus,  and,  superiorly,  with 
the  astragalo-scaphoid  ligament.  The  external 
calcaneo-scaphoid  ligament  is  short,  lying  in 
the  hollow  between  the  astragalus  and  os  calcis, 
and  passes  from  the  ridge  on  the  anterior  part  of 
the  os  calcis  to  the  outer  side  of  the  scaphoid. 
CALCANEO-  The  os  calcis  articulates  with 

CUBOID  JOINT.  the  os  cuboides   nearly   on   a 

line  with  the  joint  between  the  astragalus  and 
the  scaphoid.  The  bones  are  firmly  connected 
by  the  inferior  calcaneo- cuboid  ligament,  of 
which  the  superficial  portion,  the  ligamentum 
longum  plantce,  is  attached  to  the  os  calcis  as 
far  as  the  tubercle,  and  passes  forwards  to  the 
plantar  aspect  of  the  cuboid  ;  some  of  its  fibres 
extend  to  the  second,  third,  and  fourth  meta- 
tarsal  bones,  and  complete  the  canal  for  the 
tendon  of  the  peroneus  longus.  The  ligamen- 
tum breve  plantce  is  very  broad,  and  passes 
from  the  os  calcis  to  the  inner  side  of  the  cuboid  bone. 

The  dorsal  ligament  connects  the  upper  surfaces  of  the  bones. 


1.  Calcaneo-scaphoid 

ligament. 

2.  Calcaneo-cuboid 

ligament. 


576 


TARSO-METATAKSAL   JOINTS. 


The  remaining  bones  of  the  tarsus  are  connected  and  main- 
tained in  position  by  dorsal  and  plantar  ligaments,  and  strong 
interosseous  bands  which  pass  between  their  contiguous  surfaces. 
137.  Though  there  is   very  little  motion  between 

any  two  bones,  the    collective  amount  is  such 
that  the  foot  is  enabled  to  adapt  itself  accur- 
ately to  the  ground ;  pressure  is  more  equally 
ous  ligament  distributed,  and  consequently  there  is  a  firmer 
the  wedge  bones.       ^asjs  for  the  SUpp0rt  of  the  body.     Being  com- 
posed, moreover,  of  several  pieces,  each  of  which  possesses  a  certain 

FIG.  138. 


DIAGRAM   OF   THE   ARTICULATIONS    OF    THE   TABSUS    AND    THE    TARSO-METATARSUS. 


5.  Common  scapho-cuneiforin,  intercuneifomi, 

and  metatarso- cuneiform    synovial   ca- 
vity. 

6.  Cubo-metatarsal  synovial  cavity. 


1.  Posterior  calcaneo-astragaloid  synovial  cavity. 

2.  Calcaneo-scaphoid  synovial  cavity. 

3.  Calcaneo-cuboid  synovial  cavity. 

4.  Synovial  cavity  between   metatarsal    bone  of 

great  toe,  and  internal  cuneiform  bone. 

elasticity,  the  foot  gains  a  general  springiness  and  strength  which 
could  not  have  resulted  from  a  single  bone. 

TARSO-META-  The  tarsus  articulates  with  the  metatarsus  in 

TARSAL  JOINTS.  an  oblique  line  which  inclines  backwards  on  its 
outer  side.  This  line  is  interrupted  at  the  joint  of  the  middle 
cuneiform  bone  and  the  second  metatarsal  bone.  Here  there  is  a 
deep  recess,  so  that  the  base  of  this  metatarsal  bone  is  wedged  in 
between  the  internal  and  external  cuneiform  bones. 


SYNOVIAL  MEMBRANES  OF  THE  TARSUS.         577 

These  joints  are  maintained  in  position,  above,  by  dorsal  tarso- 
metatarsal  ligaments,  and,  below,  by  plantar  ligaments.  Inter- 
osseous  ligaments  also  pass  between  the  wedge  bones,  keeping 
them  in  their  respective  places  (fig.  137). 

The  metatarsal  bones  are  connected  to  those  at  their  proximal 
and  distal  ends  by  dorsal  and  plantar  ligaments :  those  at  the 
proximal  extremities  are  very  strong,  and  are  supplemented  by 
interosseous  fibres,  as  in  the  metacarpus,  p.  350. 

The  distal  extremities  of  the  metatarsal  bones  are  united  by 
the  transverse  metatarsal  ligament ;  this  extends  from  the  great 
to  the  little  toe  on  their  plantar  surfaces. 

SYNOVIAL  MEM-  Exclusive  of  the  ankle-joint  and  the  phalanges 
BRANES  OF  THE  of  the  toes,  the  bones  of  the  foot  are  provided  with 
TARSUS.  gjx  distinct  synovial  membranes  ;  namely — 

1.  Between  the  posterior  articular  surface  of  the  os  calcis  and 
that  of  the  astragalus.  - 

2.  Between  the  head  of  the  astragalus  and  the  scaphoid,  and 
between  the  anterior  articular  surface  of  the  astragalus  and  os 
calcis. 

3.  Between  the  os  calcis  and  the  os-  cuboides.  . 

4.  Between  the  inner  cuneiform  bone  and  the  metatarsal  bone 
of  the  great  toe. 

5.  Between  the  scaphoid  and  the  three  cuneiform  bones,  and 
between  these  and  the  adjoining  bones  (the  great  toe  excepted). 

6.  Between  the  os  cuboides  and  the  fourth  and  fifth  metatarsal 
bones. 

The  joints  formed  between  the  distal  ends  of  the  metatarsal 
bones  and  the  phalanges  of  the  toes,  and  the  several  inter- 
phalangeal  joints,  are  connected  in  all  respects  like  those  of  the 
fingers.  See  the  description  given  in  the  dissection  of  the  hand 
(p.  351). 


FP 


578 


DISSECTION  OF  THE  BRAIN. 

MEMBRANES  OF     PREVIOUS  to  the  examination  of  $\e  brain  itself, 
THEBfiAiN.  we  should  study  the   structure   and  uses  of  the 

three  membranes  by  which  it  is  surrounded. 

The  first,  the  dura  mater,  has  been  described  (p.  6).  The 
second  is  a  serous  membrane,  termed  the  arachnoid  ;  the  third  is 
a  vascular  one,  termed  the  pia  mater. 

ARACHNOID  This    second     investment   forms    the   smooth, 

MEMBRANE.  polished  surface  of  the  brain,  exposed  after  the 

removal  of  the  dura  mater.  It  is  named  arachnoid,  from  the 
resemblance  of  its  texture  to  a  spider's  web.  It  is  a  serous  mem- 
brane, and,  like  all  others  of  the  kind,  forms  a  closed  sac,  one  part 
of  which,  the  parietal  layer,  lines  the  under  surface  of  the  dura 
mater;  the  other,  the  visceral,  is  reflected  over  the  brain. 

The  opposed  surfaces  of  this  membrane  are  polished,  and 
lubricated  by  a  serous  fluid  which  diminishes  friction ;  since  the 
brain  is  moved  with  a  slight  pulsation,  caused  in  part  by  the 
action'  of  the  heart,  in  part  by  respiration.  The  parietal  layer 
is  so  thin  that  it  can  be  demonstrated  as  a  distinct  layer  only  in 
a  few  places ;  it  consists  of  little  more  than  a  layer  of  squamous 
epithelium,  lining  the  inner  aspect  of  the  dura  mater.  The 
visceral  layer  is  colourless  and  transparent ;  it  is  spread  uniformly 
over  the  surface  of  the  brain,  and  does  not  dip  into  the  furrows 
between  the  convolutions.  On  account  of  its  extreme  tenuity, 
and  its  close  adhesion  to  the  pia  mater,  it  cannot  be  readily 
separated  from  this  membrane ;  but  there  are  places,  especially  at 
the  base  of  the  brain,  termed  subarachnoid  spaces,  where  the 
arachnoid  membrane  can  be  seen  distinct  from  the  subjacent 
pia  mater. 


DISSECTION    OF    THE    BRAIN.  579 

STJBABACHNOID  Wherever  the  arachnoid  membrane  is  separated 
SPACES  AND  FLUID,  from  the  pia  rnater  a  serous  fluid  (cerebro-spinal} 
intervenes,  contained  in  the  meshes  of  a  very  delicate  areolar 
tissue.  The  spaces  between  them  are  termed  subarachnoid. 
They  are  very  manifest  in  some  places.  For  instance,  there  is 
one  well-marked  space  in  the  longitudinal  fissure,  where  the 
arachnoid  does  not  descend  to  the  bottom,  but  passes  across  the 
edge  of  the  falx  cerebri,  a  little  above  the  corpus  callosum.  At 
the  base  of  the  brain,  there  are  two  of  considerable  size :  one  is 
situated  between  the  anterior  border  of  the  pons  Varolii  and  the 
commissure  of  the  optic  nerves ;  the  other  between  the  cere- 
bellum and  the  medulla  oblongata.  In  the  spinal  cord,  also,  there 
is  a  considerable  interval  occupied  by  fluid  between  the  arachnoid 
and  the  pia  mater.  The  purpose  of  this  fluid  is,  not  only  to  fill 
up  space,  as  fat  does  in  other  parts,  but  mechanically  to  protect 
the  nervous  centres  from  the  violent  shocks  and  vibrations  to  which 
they  would  otherwise  be  liable. 

The  brain  therefore  may  be  said  to  be  supported  in  a  fluid, 
which  insinuates  itself  into  all  the  inequalities  of  the  surface,  and 
surrounds  all  the  nerves  as  far  as  the  foramina,  through  which  they 
pass.  This  fluid  sometimes  escapes  through  the  ear,  in  cases  of 
fracture  through  the  base  of  the  skull,  involving  the  meatus 
auditorius  internus  and  the  petrous  portion  of  the  temporal  bone.* 
This,  the  immediate  investing  membrane  of  the 
brain,  is  extremely  vascular,  and  composed  of  a 
minute  network  of  blood-vessels  held  together  by  delicate  connec- 
tive tissue.  From  its  internal  surface  vessels  pass  off  at  right 
angles  into  the  interior  of  the  brain.  The  pia  mater  dips  into  the 
fissures  between  the  convolutions,  and  penetrates  into  the 
ventricles  for  the  supply  of  their  interior,  forming  the  velum 
interpositum  and  the  choroid  plexuses^ 

*  The  cerebro-spinal  fluid  varies  in  amount  from  two  drachms  to  two  ounces.  It 
is  a  clear,  limpid  fluid,  slightly  alkaline,  containing  98'5  parts  of  water,  and  1'5 
parts  of  solid  matter.  The  cerebro-spinal  fluid  of  the  encephalon  and  that  of  the 
spinal  cord  communicate. 

f  The  arachnoid  is  said  to  be  supplied  with  filaments  from  the  motor  root  of  the 
fifth,  the  facial  and  the  spinal  accessory  nerves ;  the  pia  mater  by  the  third,  sixth, 
facial,  pneumogastric,  spinal  accessory  and  sympathetic  nerves. 

p  p  2 


580 


DISSECTION    OF    THE    BRAIN. 


ARTERIES  OP 
THE  BRAIN. 

INTERNAL 
CAROTID. 


Bulb  of  olfactory  nerve   . 


Second     pair     or     optic 
neiTe      .    .    . 


Locus  perforatus  anticus. 
Tractus  opticus  .... 

Crus  cerebri 

Third  pair  of  nerves    .    . 
Fourth  pair  of  nerves  .    . 

Fifth  pair  of  nerves    .     . 
Sixth  pair  of  nerves    .     . 


Pyramid 
Olive 


Vertebral  artery 


Anterior  spinal  a. 


The  brain  is  supplied  with  blood  by  the  two 
internal  carotid  and  the  two  vertebral  arteries. 

This  artery  enters  the  skull  through  the  carotid 
canal  in  the  temporal  bone,  and  ascends  very 


Fro.  139. 


Interior  cerebral  a. 


Lamina  cinerea. 
Middle  cerebral  a. 
Tuber  cineremn. 
Mammillary  body. 
Locus  perforatus  niedius. 
Posterior  cerebral  a. 
Superior  cerebellar  a. 
Pons  Varolii. 
Inferior  cerebellar  a. 
Seventh  pair  of  nerves . 

Eighth  pair  of  nerves. 
Ninth  pair  of  nerves. 
Cerebellum. 


tortuously  by  the  side  of  the  body  of  the  sphenoid,  along  the  inner 
wall  of  the  cavernous  sinus.  It  appears  on  the  inner  side  of  the 
anterior  clinoid  process,  and,  after  giving  off  the  ophthalmic, 
divides  into  the  anterior  and  middle  cerebral  and  posterior  com- 
municating arteries. 


DISSECTION    OP    THE    BRAIN.  581 

a.  The  anterior  cerebral  artery  passes  forwards  to  reach  the  longi- 
tudinal fissure  between  the  hemispheres,  curves  round  the  front  part  of 
the  corpus  callosum,  then  runs  backwards  along  its  upper  surface  (under 
the  name  of  the  artery  of  the  corpus  callosum},  and  terminates  in 
branches  which  anastomose  with  the  posterior  cerebral.  The  anterior 
cerebral  arteries  of  opposite  sides  run  close  together ;  and  at  the  base  of 
the  brain  are  connected  by  a  transverse  branch,  called  the  anterior 
communicating  artery  (fig.  139). 

6.  The  middle  cerebral  artery,  the  largest  branch  of  the  internal 
carotid,  runs  deeply  within  the  fissure  of  Sylvius,  and  divides  into  many 
branches,  distributed  to  the  anterior  and  middle  lobes.  Near  its  origin 
it  gives  off  a  multitude  of  small  arteries,  which  pierce  the  locus  per- 
foratus  anticus  to  supply  the  corpus  striatum. 

c.  The  posterior  communicating  artery  proceeds  directly  backwards 
to  join  the  posterior  cerebral ;  thus  establishing  at  the  base  of  the  brain 
the  free  arterial  inosculation  called  the  circle  of  Willis. 

d.  The  anterior  choroid  artery,  a  small  branch  of  the  internal  carotid, 
arises  external  to  the  posterior  communicating  artery.     It  runs  back- 
wards, and  enters  the  fissure  at  the  bottom  of  the  middle  horn  of  the 
lateral  ventricle,  to  terminate  in  the  choroid  plexus  of  that  cavity. 

VERTEBRAL  This  artery,  a  branch  of  the  subclavian  in  the 

ARTERY.  firg£  par^  of  j^s  course,  winds  backwards  along  the 

arch  of  the  atlas,  and  enters  the  skull  through  the  foramen  magnum 
by  perforating  the  posterior  occipito-atlantoid  ligament.  It  then 
curves  round  the  medulla  oblongata  between  the  hypoglossal  nerve 
and  the  anterior  root  of  the  first  cervical.  At  the  lower  border 
of  the  pons  Varolii,  the  two  arteries  unite  to  form  a  single  trunk 
— the  '  basilar ' — which  is  lodged  in  the  groove  along  the  middle 
of  the  pons,  and  bifurcates  at  its  upper  border  into  the  posterior 
cerebral  arteries. 

Each  vertebral  artery,  before  joining  its  fellow,  gives  off — 

a.  A  posterior  meningeal  branch,  distributed  to  the  posterior  fossa  of 
the  skull. 

b.  Anterior  and  posterior  spinal  arteries,  which  run  along  the  median 
fissures  of  the  front  and  back  surfaces  of  the  spinal  cord. 

c.  The  inferior  cerebellar  artery,  sometimes  a  branch  of  the  basilar, 
but  more  frequently  of  the  vertebral,  passes  backwards  between  the  hypo- 


582  DISSECTION    OF    THE    BEAIN. 

glossal  and  pneumogastric  nerves,  and  divides  into  two  branches,  which 
are  distributed  to  the  inferior  surface  of  the  cerebellum. 

The  basilar  artery,  formed  by  the  junction  of  the  two  vertebral, 
in  its  course  along  the  pons  gives  off  on  each  side — 

a.  Transverse  branches  which  pass  outwards  on  the  pons  :  one,  the 
auditory,  enters  the  meatus  auditorius  internus  with  the  auditory  nerve, 
to  be  distributed  to  the  internal  ear. 

b.  The  anterior  cerebellar,  which  supplies  the  front  part  of  the  lower 
surface  of  the  cerebellum  and   anastomoses  with  the  other  cerebellar 
arteries. 

c.  The  superior  cerebellar,  which  is  distributed  to  the  upper  surface 
of  the  cerebellum ;  the  valve  of  Vieussens  and  part  of  the  velum  inter- 
positum. 

d.  The  two  posterior  cerebral,  the  terminal  branches  into  which  the 
basilar  artery  divides,  run  outwards  and  backwards,  in  front  of  the  third 
nerve.     They  wind  round  the  crura  cerebri  and  divide  into  numerous 
branches  which  supply  the  under  surface  of  the  posterior  cerebral  lobes, 
and  ultimately  inosculate  with  the  other  cerebral  arteries.     Each  gives 
off  a  small  posterior  choroid  artery,  distributed   to  the  velum    inter- 
positum,  and  choroid  plexus. 

CIRCLE  OF  This  important  arterial  inosculation  (fig.  139)  is 

WILLIS.  formed,  laterally,  by  the  two  anterior  cerebral, 

the  two  internal  carotid,  and  the  two  posterior  communicating 
arteries  ;  in  front,  it  is  completed  by  the  anterior  communicating 
artery ;  behind,  by  the  two  posterior  cerebral.  The  tortuosity  of 
the  large  arteries  before  they  enter  the  brain  serves  to  mitigate 
the  force  of  the  heart's  action ;  and  the  circle  of  Willis  provides  a 
free  supply  of  blood  from  other  vessels,  in  case  any  accidental  cir- 
cumstance should  stop  the  flow  of  blood  through  any  of  the  more 
direct  channels.* 

*  In  many  of  the  long-necked  herbivorous  quadrupeds  a  provision  has  been  made 
in  the  disposition  of  the  internal  carotid  arteries,  for  the  purpose  of  equalising  the 
force  of  the  blood  supplied  to  the  brain.  Tho  arteries,  as  they  enter  the  skull,  divide 
into  several  branches,  which  again  unite  and  form  a  remarkable  network  of 
arteries,  called  by  Galen,  who  first  described  it,  the  'rete  mirabil-e.'  The  object  of  this 
evidently  is  to  moderate  the  rapidity  with  which  the  blood  would  otherwise  enter  the 
cranium  in  the  different  positions  of  the  head,  and  thus  preserve  the  brain  from 
those  sudden  influxions  to  which  it  would  under  other  circumstances  be  continually 
exposed. 


DISSECTION    OF   THE    BBAIN.  583 

PECULIARITIES  Besides  the  circle  of  Willis,  there  are   other 

OF  THE  CEREBRAL  peculiarities  relating  to  the  circulation  of  the 
CIRCULATION.  blood  in  the  brain  :  namely,  the  length  and  tor- 

tuosity of  the  four  great  arteries  as  they  enter  the  skull ;  their 
passage  through  tortuous  bony  canals  ;  the  spreading  of  their  rami- 
fications in  a  very  delicate  membrane,  the  pia  mater,  before  they 
enter  the  substance  of  the  brain ;  the  minuteness  of  the  capillaries, 
and  the  extreme  thinness  of  their  walls  ;  the  formation  of  the  venous 
sinuses  (p.  8),  which  do  not  accompany  the  arteries ;  the  chordae 
Willisii  in  the  superior  longitudinal  sinus ;  the  absence  of  valves  in 
the  sinuses ;  and  the  confluence  of  no  less  than  six  sinuses,  forming 
the  torcular  Herophyli,  at  the  internal  occipital  protuberance. 

GENERAL  Di-  The  mass  of  nervous  substance  contained  within 

VISION  OF  THE  the  cranium,  comprised  under  the  common  term 
BEAIN-  brain  (encephalon),  is  divided  into  four  parts :  the 

cerebrum,  which  occupies  the  whole  of  the  upper  part  of  the 
cranial  cavity ;  the  cerebellum,  or  smaller  brain,  which  occupies 
the  space  below  the  tentorium  cerebelli ;  the  pons  Varolii,  or  the 
quadrilateral  mass  of  white  fibres  which  rests  upon  the  basilar 
process  of  the  occipital  bone  ;  and  the  medulla  oblongata,  situated 
below  the  pons,  and  continuous  with  the  spinal  cord  (fig.  142). 

The  weight  of  the  entire  encephalon  bears  a  proportionate  re- 
lation to  the  intellectual  power.  The  result  of  observations  shows 
that  it  averages  in  males  about  50  ounces,  and  in  females  about 
44  ounces. 

MEDULLA  OB-  This  term  is  applied  to  that  part  of  the  cerebro- 

LONGATA.  spinal  axis  which  is  placed  below  the  pons  Varolii, 

and  is  continuous  with  the  spinal  cord  on  a  level  with  the  upper 
border  of  the  atlas.  It  is  slightly  pyramidal  in  shape,  with  the 
broad  part  above.  It  lies  on  the  basilar  groove  of  the  occipital 
bone,  and  descends  obliquely  backwards  through  the  foramen 
magnum.  Its  posterior  surface  is  received  into  the  fossa  (vallecula) 
between  the  hemispheres  of  the  cerebellum.  It  is  about  an  inch 
and  a  quarter  in  length,  and  nearly  an  inch  thick  at  its  broadest 
part. 

In  front  and  behind,  the   medulla   is   marked   by  a   median 


584 


DISSECTION   OP   THE    BRAIN. 


fissure,  the  anterior  and  posterior  median  fissures,  which  are  the 
continuations  of  the  median  fissures  of  the  spinal  cord.  The 
anterior  ends,  below  the  pons  Varolii,  in  a  cul-de-sac,  termed  the 
foramen  cczcum,  and  is  occupied  by  a  process  of  pia  mater.  The 
posterior  runs  along  the  floor  of  the  fourth  ventricle  as  a  shallow 
median  groove. 

The  surface  of  the  medulla  is  marked  out  on  each  side  into 
four   longitudinal   columns,  which   receive  the   following   names 

FIG.  140. 


1.  Gasserian  ganglion. 

2.  Motor  root    of    the 

fifth  n. 


C.  Crus  cerebri. 
P.  V.  Pons  Varolii. 
P.  Anterior  pyramid. 
O.  Olive. 

B.  Restiform   tract   or 
body. 


3.  Third  n. 

4.  Aroiform  fibres. 

5.  Sensitive  root  of  the 

fifth  n. 

6.  Sixth  n. 

7.  Two  divisions  of  the 

seventh  n. 

8.  Three    divisions    of 

the  eighth  n. 

9.  Ninth  or  hypoglos- 

sal  n. 


DIAGRAM    OF   THE    FRONT    SURFACE    OF    THE    MBDULLA    OBLONGATA. 

from  before  backwards  :  the  anterior  pyramids,  the  olivary  bodies, 
the  restiform  bodies,  and  the  posterior  pyramids. 

The  anterior  pyramids  are  two  columns  of  white  matter, 
narrow  below,  but  increasing  gradually  in  breadth  as  they 
ascend  towards  the  pons.  At  this  part  they  become  constricted, 
and  may  be  traced  through  the  pons  into  the  crura  cerebri. 
The  fibres  of  which  they  are  in  the  main  composed  are  derived 
from  the  anterior  columns  of  the  spinal  cord,  and  consist  there- 
fore of  motor  fibres.  On  separating  the  pyramids  about  an  inch 


DISSECTION    OP    THE    BRAIN. 


585 


below  the  pons,  bundles  of  nerves  are  seen  decussating  across 
the  anterior  fissure  (fig.  140).  This  is  the  explanation  of  cross 
paralysis — i.e.  when  one  side  of  the  brain  is  injured,  the  loss 
of  motion  is  manifested  on  the  opposite  side  of  the  body.*  This 
decussation,  which  consists  of  three  or  four  bundles  on  each  side, 
involves  only  the  inner  fibres  of  the  pyramid ;  the  outer  fibres 
ascend  through  the  pons  without  crossing.  The  decussating 
fibres  are  the  continuations  upwards  of  the  deep  fibres  of  the 

FIG.  141. 


DIAGRAM    OF    THE   FOUETH   VENTHICLE   AND  BESTIl'OEM    BODIES. 


1.  Thalamus  options. 

2.  Nates  and  testes. 

3.  Origin  of  fourth  nerve. 


4.  Processns  a  cerebello  ad  testes. 

5.  Restiform  bodies  diverging. 

6.  Origins  of  seventh  or  auditory  nerve. 


lateral  columns  of  the  spinal  cord,  which  here  come  forwards  to 
the  surface,  and  push  aside  the  anterior  columns. 

The  olivary  bodies  are  the  two  oval  eminences  situated  on  the 
outer  side  of  the  anterior  pyramids,  from  which  they  are  separated 
by  a  shallow  depression.  They  do  not  ascend  quite  as  high  as  the 
pons.  They  consist  externally  of  white  matter ;  and,  when  cut 

*  The  phenomenon  of  cross  paralysis  of  sensation  is  explained  by  the  fact  made 
out  by  Brown-S6quard,  that  the  paths  of  sensory  impressions  cross  each  other  in  the 
grey  matter  of  the  cord. 


586  DISSECTION    OP   THE    BEAIN. 

into,  their  interior  presents  an  undulating  line  of  yellowish-brown 
colour,  called  from  its  zigzag  shape  the  corpus  dentatum.  This, 
which  is  sometimes  called  the  olivary  nucleus,  forms  an  interrupted 
circle,  incomplete  at  its  upper  and  inner  side,  so  that  it  nearly 
isolates  the  white  matter  within.  The  small  grey  mass  placed  above 
the  corpus  dentatum,  and  similarly  composed  of  grey  matter,  is 
called  the  accessory  olivary  nucleus.  At  the  lower  part  of  the 
olivary  body,  some  white  fibres  may  be  observed  arching  round 
from  the  anterior  median  fissure,  constituting  the  ardform,  fibres 
of  Eolando. 

The  restiform  bodies,  situated  to  the  outer  side  of  and  behind 
the  olivary  bodies,  are  the  continuations  upwards  of  the  posterior 
columns  of  the  spinal  cord.  As  they  ascend  they  diverge  and 
pass  into  the  cerebellum,  constituting  its  inferior  peduncles 
(fig.  141).  Owing  to  this  divergence,  the  grey  matter  of  the 
medulla  is  exposed,  so  that  the  floor  of  the  fourth  ventricle  (of 
which  the  restiform  bodies  assist  in  forming  the  lateral  boundaries) 
is  mainly  composed  of  grey  matter.  The  restiform  bodies  consist 
of  white  fibres  derived  from  the  posterior  and  lateral  columns 
of  the  spinal  cord ;  in  its  interior  is  some  grey  matter  continuous 
with  that  in  the  posterior  part  of  the  cord. 

The  posterior  pyramids  are  the  two  slender  white  columns  on 
each  side  of  the  posterior  median  fissure.  Ascending,  they 
diverge  and  thus  form  the  apex  of  the  fourth  ventricle.  At  their 
point  of  separation  the  posterior  pyramids  enlarge,  and  form  the 
processus  clavatus ;  after  which  they  diminish  in  size,  and  run  up 
with  the  restiform  bodies,  which,  however,  they  soon  leave  and  are 
continued  upwards  into  the  cerebrum  along  the  floor  of  the  fourth 
ventricle. 

Emerging  from  the  anterior  median  fissure  may  be  noticed 
some  superficial  transverse  white  fibres  which  cross  below  the 
lower  extremity  of  the  olivary  bodies,  and  sometimes  also  the 
anterior  pyramids ;  these  are  known  as  the  ardform,  fibres  of 
Rolando  (fig.  140).  They  are  probably  connected  with  white 
fibres  which  run  horizontally,  constituting  an  imperfect  septum 
between  the  two  halves  of  the  medulla,  and  may  be  seen  when  a 


DISSECTION    OF    THE    BEAIN.  587 

longitudinal  section  is  carefully  made  through  its  middle.  The 
majority  of  these  septal  fibres  enter  the  olivary  bodies,  and  then 
emerging  through  the  grey  matter  of  the  corpus  dentatum, 
become  continuous  with  the  fibres  of  the  restiform  bodies  and 
lateral  tracts ;  others  pass  out  from  the  posterior  fissure  and 
wind  round  the  restiform  bodies.  These  latter  fibres  are  the  trans- 
verse strice,  seen  on  the  floor  of  the  fourth  ventricle,  some  of  which 
form  the  roots  of  the  auditory  nerves. 

PONS  VAROLII  This   convex    eminence     of    transverse   white 

OR  GREAT  COMMIS-  fibres  (p.  584)  is  situated  at  the  base  of  the 
SURE  OF  THE  CE-  brain,  immediately  above  the  medulla  oblongata. 
It  rests  upon  the  basilar  groove  of  the  occipital 
bone,  and  in  its  antero-posterior  diameter  measures  rather  more 
than  an  inch.  The  upper  margin  is  convex,  and  arches  over  the 
crura  cerebri ;  the  lower  is  nearly  straight,  being  separated  from 
the  medulla  by  a  transverse  groove.  On  each  side  the  pons 
becomes  narrower,  in  consequence  of  the  transverse  fibres  being 
more  closely  aggregated ;  these  enter  the  anterior  part  of  the 
cerebellum,  constituting  its  middle  crus.  Along  the  middle 
runs  a  shallow  groove  which  lodges  the  basilar  artery.  If  the 
pia  mater  be  removed,  we  observe  how  the  superficial  fibres 
pass  transversely,  to  connect  the  two  hemispheres  of  the  cere- 
bellum. Throughout  the  mammalia  the  size  of  the  pons  bears  a 
direct  ratio  to  the  degree  of  development  of  the  lateral  lobes  of 
the  cerebellum ;  therefore  it  is  larger  in  man  than  in  any  other 
animal.* 

When  the  superficial  transverse  fibres  are  dissected  off,  the 
longitudinal  fibres  of  the  anterior  pyramids  are  seen  passing  up 
beneath  them  to  enter  the  crura  cerebri,  like  a  river  under  a 
bridge,  hence  its  name  of  pons.  These  pyramidal  fibres  are 
separated  into  yet  smaller  bundles  by  deeper  transverse  fibres, 
which,  like  the  superficial  transverse  ones,  are  continued  into  the 
cerebellum. 

Besides  the  transverse  and  longitudinal  fibres  just  described, 

*  Birds,  reptiles,  and  fishes  have  no  pons,  as  there  are  no  lateral  lobes  to  the 
cerebellum. 


588  DISSECTION    OF    THE    BRAIN. 

the  pons  contains  a  considerable  amount  of  grey  matter,  which  is 
distributed  between  the  transverse  and  longitudinal  fibres. 

The  pons,  like  the  medulla  oblongata,  has  an  imperfect 
median  septum,  composed  of  horizontal  fibres,  some  of  which  at  its 
anterior  border  surround  the  crura  cerebri. 

The    cerebrum    in  man  is  so  much  more  de- 

CKRFBRUM 

veloped  than  the  other  parts  of  the  encephalon 
that  it  completely  overlies  them,  and  forms  by  far  the  largest 
portion.  It  is  oval  in  form,  and  convex  on  its  external  aspect.  It 
is  divided  in  the  middle  line  into  two  symmetrical  parts,  termed 
the  right  and  left  hemispheres,  by  the  deep  longitudinal  fissure, 
which  is  occupied  by  the  falx  cerebri  (p.  7).*  The  cerebrum  is 
composed  of  numerous  parts — viz.,  of  certain  internal  ganglionic 
masses,  the  corpora  striata,  optic  thalami,  and  corpora  quadri- 
FIG.  142.  gemina;  of  commissural  white  fibres, 

the  fornix,  corpus  callosum,  and  the  com- 
missures of  the  third  ventricle;  of  the 
pineal  arid  pituitary  bodies  ;  and,  lastly,  of 
the  two  lateral  hemispheres,  which  overlie 
and  conceal  the  parts  previously  men- 
tioned. 

The  cerebrum  rests  upon  the  anterior 
and  middle  fossae  of  the  base  of  the  skull, 
and  the  tentorium  cerebelli.  There  are 

DIAGRAM    OF   THE    GENERAL 

DIVISIONS  OF  THE  BBAiN.  three  surfaces  to  each  hemisphere  :  an 
i,  2, 3.  Anterior,  middle,  and  poste-  external  or  convex  i  an  inner  or  median  : 

rior  lobes  of  the  cerebrum. 

4.  cerebellum.  and  an  inferior,  interrupted  by  the  fissure 

5.  Pons  Varolii.  ^  ' 

6.  Medulla  oblongata.  of  Sylvius. 

By  widely  separating  the  two  hemispheres  at  the  longitudinal 
fissure  (the  brain  being  in  its  natural  position),  we  discover  that 
they  are  connected  in  the  middle  by  the  transverse  white  com- 

*  Examples  are  occasionally  met  with,  where  the  longitudinal  fissure  is  not 
exactly  in  the  middle  line,  the  consequence  of  which  want  of  symmetry  is,  that  one 
hemisphere  is  larger  than  the  other.  Bichat  ('  Recherches  physiologiques  sur  la  \rie 
et  la  Mort,'  Paris,  1829)  was  of  opinion  that  this  anomaly  exercised  a  deleterious 
influence  on  the  intellect.  It  is  remarkable  that  the  examination  of  his  own  brain 
after  death  went  to  proye  the  error  of  his  theory. 


DISSECTION    OF    THE    BRAIN. 


589 


missure,  called  the  corpus  callosum.     In  front  of,  and  behind  this 
white  mass,  the  fissure  extends  to  the  base  of  the  brain. 

The  surface  of  each  hemisphere  is  mapped  out  by  tortuous 
eminences  termed  convolutions  (gyri),  separated  from  each  other 
by  deep  furrows,  sulci.  Many  of  the  furrows  are  occupied  by 
the  large  veins  in  their  course  to  the  sinuses ;  others  are  filled 
with  subarachnoid  fluid.  The  convolutions  are  folds  of  the  brain, 
for  the  purpose  of  increasing  the  extent  of  the  surface  for  the 
grey  nerve-substance.  They  are  not  symmetrical  on  both  sides, 
although  they  follow  a  somewhat  similar  arrangement.  Their 
number,  arrangement,  and  depth,  vary  somewhat  in  different 
individuals,  and,  to  a  certain  extent,  may  be  considered  an 
index  of  the  degree  of  intelligence-* 

Since  the  grey  matter  forms  a  sort  of  bark  round  the  white 
substance,  it  is  often  called  the  cortical  substance.  The  depth 
of  the  sulci  between  the  convolutions  varies  in  different  brains, 
from  an  inch  to  half  an  inch ;  hence  it  follows  that  two  brains 
of  equal  size  may  be  very  unequal  in  point  of  extent  of  surface 
for  the  grey  matter,  and  therefore  in  amount  of  intellectual 
capacity.  Under  the  microscope  the  cortical  layer  is  seen  to 
consist  of  four  layers,  two  grey  alternating  with  two  of  white, 
the  external  layer  being  always  white.f 

Some  of  the  sulci,  from  their  depth,  regularity,  and  early 
period  of  development,  are  termed  the  primary  fissures,  and  map 
out  the  surface  of  the  cerebrum  into  its  different  lobes.  Of  these 
there  are  three  :  the  fissure  of  Sylvius,  the  fissure  of  Rolando 
or  central  fissure,  and  the  parieto-occipital  fissure  (fig.  143). 

*  Those  who  wish  to  investigate  the  cerebral  convolutions  in  their  simplest  form 
in  the  lower  classes  of  mammalia,  and  to  trace  them  through  their  successive  develop- 
ment and  arrangement  into  groups  as  we  ascend  to  the  higher  classes,  should 
consult  Leuret,  'Anatomie  comparee  duSysteme  Nerreux  considered  dans  ses  Kapports 
avec  Tlntelligence,'  Paris,  1839  ;  alsoFoville,  'Traite  de  1'Anat.  du  Systeme  Nerveux,' 
&c.,  Paris,  1844.  The  convolutions  of  the  human  brain  have  been  described  by 
Ecker,  'On  the  Convolutions  of  the  Human  Brain,'  1873;  and  by  Turner,  'The 
Convolutions  of  the  Human  Brain,  topographically  considered,'  Edin.  1866. 

f  Six  layers  may  be  demonstrated  in  some  situations,  chiefly  near  the  corpus 
callosum  and  the  occipital  lobe.  For  an  account  of  these  laminae  see  Lockhart 
Claske,  'Proceed.  Eoyal  Society,'  1863. 


590 


DISSECTION    OP    THE    BRAIN. 


The  fissure  of  Sylvius  is  seen  on  the  base  of  the  cerebrum, 
and  receives  the  lesser  wing  of  the  sphenoid  bone.  It  curves 
outwards  as  a  deep  cleft,  and  divides  into  two  rami ;  an  as- 
cending or  vertical,  about  an  inch  in  length,  and  a  posterior  or 
horizontal  ramus,  which  passes  backwards,  and  ends  about  the 
middle  of  the  hemisphere. 

iio.  143. 


YIEW  OF  THE  CONVOLUTIONS  AND  FISSURES  OF  THE  EXTERNAL  SURFACE  OF  THE 
BRAIN  (LEFT  SIDE). 


A.  Fissure  of  Rolando. 

u.  Fissure  of  Sylvius. 

c.  Inter-parietal  fissure. 

P.O.  Parieto-occipital  fissure. 

c.m.  Calloso-marginal  fissure. 

F.  Frontal  lobe. 

p.  Parietal  lobe. 

o.  Occipital  lobe. 

T.S.  Temporo-sphenoidal  lobe. 

A.F.  Ascending  frontal  convolution. 

A.P.  Ascending  parietal  convolution. 

/i,/2,/3.  Superior,  middle,  and  inferior  frontal 


convolutions,  separated  by  the  superior 
and  inferior  frontal  sulci. 

pi,  yl.  Superior  and  inferior  parietal  convolu- 
tions, separated  by  the  inter-parietal 
fissure. 

of,  o2,  o3.  Superior,  middle,  and  inferior  occi- 
pital convolutions,  separated  by  the  occi- 
pital fissures. 

ti,  t2,  <3.  Superior,  middle,  and  inferior  tem- 
poro-sphenoidal  convolutions,  separated 
by  the  superior  and  inferior  temper  o- 
sphenoidal  fissures. 


The  fissure  of  Rolando  or  central  fissure  runs  obliquely  over 
the  outer  surface  of  the  hemisphere.     It  commences  close  to  the 


DISSECTION    OP    THE    BEAIN.  591 

longitudinal  fissure  about  its  middle,  then  runs  downwards  and 
forwards,  and  terminates  a  little  above  the  fork  of  the  Sylvian 
fissure. 

The  parieto-occipital  fissure  is  seen  on  the  median  surface 
of  the  hemisphere  towards  its  posterior  part.  It  begins  on  its 
median  surface  about  half  an  inch  behind  the  corpus  callosum, 
then  ascends  nearly  vertically,  and  ends  on  the  external  aspect 
of  the  cerebrum  about  an  inch  from  the  longitudinal  fissure.* 

Other  important  fissures  besides  the  primary  just  described 
are  seen  on  the  cerebral  surface.  They  are  chiefly  found  on  the 
median  aspect  of  the  hemisphere,  and  are  as  follows  (fig.  144)  : — 

The  calloso-marginal  fissure  runs  nearly  parallel  with  the 
anterior  two-thirds  of  the  corpus  callosum,  then,  changing  its 
direction,  it  ascends  obliquely  and  terminates  on  the  external 
aspect  of  the  hemisphere,  where  rt  forms  a  deep  notch  immedi- 
ately behind  the  fissure  of  Kolando. 

The  calcarine  fissure,  also  seen  on  the  median  surface,  begins 
close  to  the  posterior  border  of  the  cerebrum,  and  then,  running 
nearly  horizontally  forwards,  terminates  below  the  corpus  callosum. 
Midway  in  its  course  it  is  joined  at  an  acute  angle  by  the  parieto- 
occipital  fissure. 

The  primary  fissures  form  the  boundaries  of  the  various  lobes 
of  which  each  hemisphere  is  composed. 

Thus  the  frontal  lobe  is  that  part  of  the  cerebrum  anterior 
to  the  fissure  of  Rolando  on  the  external  surface,  and  the  calloso- 
marginal  fissure  on  the  median.  The  parietal  lobe  is  placed 
between  the  fissure  of  Rolando  and  the  external  parieto-occipital 
fissure. 

The  occipital  lobe  consists  of  the  posterior  part  of  the  hemi- 
sphere behind  and  below  the  parieto-occipital  fissure.  The  tem- 
poro-sphenoidal  lobe  is  bounded  above  by  the  horizontal  ramus 
of  the  Sylvian  fissure,  and  forms  that  part  of  the  hemisphere 
which  occupies  the  middle  cerebral  fossa. 

The  island  of  Reil  or  the  central  lobe  lies  deep  in  the  fissure 

*  The  fissure  of  Rolando  is  first  seen   about  the  fifth  month  of  foetal  life ;  the 
parieto-occipital  fissure,  between  the  fourth  and  fifth  month. 


592 


DISSECTION    OP   THE    BRAIN. 


of  Sylvius.  It  consists  of  a  number  of  hidden  convolutions 
(gyri  operti}  connected;  with  those  adjoining  it,  and  corresponds 
to  the  under  surface  of  the  corpus  striatum.  The  frontal  lobe 
is  on  its  external  surface  divided  by  two  frontal  fissures  into  a 
superior,  middle,  and  inferior  frontal  convolution  (fig.  143). 

The  only  fissure  of  the  parietal  lobe  is  the  inter-parietal  sulcus, 
which  separates  the  upper  from  the  lower  parietal  convolution, 
which  latter  is  occasionally  divided  into  the  supra-marginal  and 
angular  gyrus ;  the  one  being  above,  the  other  behind  the  fissure  of 

Fie.  144. 


PO 


CONVOLUTIONS    AND    FISSURES   OF   THE    MEDIAN'  AND   TENTOBIAL   SURFACES    OF   RIGHT 

HEMISPHERE. 


c  c.  Corpus  callosum. 

A  F.  Ascending  frontal  convolution. 

A  p.  Ascending  parietal  convolution. 

p  o.  Parieto-occipital  fissure. 

p  c.  Praecuneus  or  quadrate  lobe. 

c   Cuneus. 

c    Calcarine  fissure. 

Clf.  Collateral  fissure. 


o.p.  Gyrus  foraicatns. 

cm.  Calloso-marginal  fissure. 

fi.-  Supei  ior  frontal  or  marginal  convolution. 

O.T.  Optic  thalamus. 

p.  Pituitary  body. 

rfc.  Dentate  convolution. 

to4.  Gyrus  occipito-temporalis  lateralis. 

to5.  Gyrus  occipito-temporalis  medialis. 


Sylvius.  Behind  the  fissure  of  Eolando  is  the  ascending  parietal 
convolution,  which  is  usually  continuous  with  the  ascending  frontal 
convolution,  above  and  below  the  fissure. 

The  occipital  lobe  is  composed  of  a  superior,  middle,  and  in- 
ferior occipital  convolution,  separated  by  ill-defined  sulci,  and 
connected  with  some  parietal  and  temporo-sphenoidal  convolutions 


DISSECTION    OF    THE    BRAIN.  593 

by  the  annectant  gyri.  The  temporo-sphenoidal  lobe  is  traversed 
by  two  parallel  fissures,  which  divide  it  into  a  superior,  middle, 
and  inferior  temporo-sphenoidal  convolution.  In  front  of  the 
under  aspect  of  this  lobe,  there  is  the  undnate  or  hippocampal 
convolution,  which  is  continuous  with  the  gyrus  fornicatus.  In  this 
situation  also  we  find  two  fissures,  the  hippocampal  and  the  col- 
lateral, the  former  of  which  corresponds  to  the  hippocampus  major, 
the  latter  to  the  eminentia  collateralis.  The  remaining  convolu- 
tions are  seen  on  the  median  surface  of  the  hemisphere,  and  com- 
prise the  gyrus  fornicatus,  which  coursesround  the  corpus  callosum; 
the  cuneus,  situated  between  the  parieto-occipital  and  calcarine 
fissures ;  and  the  prcecuneus  or  quadrate  lobe  placed  in  front  of  the 
parieto-occipital  fissure. 

NOMENCLATURE         The  several  objects  seen  at  the  base  of  the  brain 

OF  THE  PAETS  AT      in  the  middle  line  should  now  be  examined,  pro- 

THEBASE  OF  THE      ceeding  in  order  from  the  front  (fig.  139,  p.  580). 

In  this  description  the  cerebral  nerves  are  omitted. 

These  will  be  examined  hereafter. 

Tn  the  middle  line,  dividing  the  frontal  lobes,  is  the  longitudinal 
fissure.  By  gently  separating  these  lobes,  we  expose  the  corpus  cal- 
losum, or  the  great  transverse  commissure  which  connects  the  two 
hemispheres  of  the  cerebrum.'  Continued  backwards  and  outwards 
on  each  side  from  the  corpus  callosum  to  the  fissure  of  Sylvius  is 
a  white  band,  the  peduncle  of  the  corpus  callosum.  Extending  from 
the  corpus  callosum  to  the  optic  commissure  is  a  thin  grey  layer, 
the  lamina  cinerea.  Between  the  frontal  and  temporo-sphenoidal 
lobes  is  the  fissure  of  Sylvius,  which  lodges  the  middle  cerebral 
artery.  The  optic  commissure,  formed  by  the  union  of  the  two 
optic  tracts,  is  seen  in  the  middle  line  behind  the  lamina  cinerea. 
At  the  root  of  the  fissure  of  Sylvius  is  the  locus  perforatus* 
anticus.  Immediately  behind  the  optic  commissure  is  a  slight 
prominence  of  grey  matter,  the  tuber  cinereum;  from  this  de- 
scends a  conical  tube  of  reddish  colour,  the  infundibulum,  to  the 
apex  of  which  is  attached  the  pituitary  body.  Behind  the  tuber 

*  Called  '  perforatus '  from  its  being  perforated  by  a  number  of  blood-vessels,  for 
the  supply  of  the  corpus  striatum. 

QQ 


594  DISSECTION    OF    THE    BRAIN. 

cinereum  are  two  round  white  bodies,  the  corpora  mammillaria. 
Posterior  to  these  is  the  locus  perforatus  posticus,  which  is  bounded 
behind  by  the  pons,  and  laterally  by  the  two  diverging  crura  cere- 
bri,  two  round  cords  of  white  substance,  which  emerge  from  the 
anterior  border  of  the  pons.  Winding  round  the  outer  side  of  each 
crus  is  a  soft  white  band,  the  optic  tract. 

Examine  now  in  detail  the  various  objects  above  enumerated, 
most  of  which  are  shown  in  fig.  139. 

The  lamina  cinerea  is  a  thin  layer  of  grey  substance,  which 
connects  the  corpus  callosum,  and  the  optic  commissure ;  it  passes 
above  this  and  becomes  continuous  with  the  tuber  cinereum.  If 
the  lamina  be  torn,  which  is  very  easily  done,  an  aperture  is  made 
into  the  third  ventricle. 

The  Locus  perforatus  anticus,  placed  to  the  inner  side  of  the 
commencement  of  the  fissure  of  Sylvius,  is  composed  partly  of 
grey  substance ;  crossing  it  is  seen  a  broad  white  band,  the 
peduncle  of  the  corpus  callosum. 

The  tuber  cinereum  is  a  prominence  of  grey  matter  immediately 
behind  the  optic  commissure,  and  from  it  a  conical  tube  of  reddish 
colour,  the  infundibulum,  descends  to  the  pituitary  body.  This 
body,  which  occupies  the  sella  turcica,  is  of  reddish-brown  colour, 
and  consists  of  two  lobes;  the  anterior,  the  larger,  is  concave 
behind  to  receive  the  posterior  lobe.  It  weighs  from  five  to  ten 
grains,  and  on  section  resembles  in  structure  the  thyroid  gland, 
being  composed  of  reticular  tissue  with  numerous  cavities  filled 
with  nucleated  cells  and  granular  matter. 

The  corpora,  albicantia  or  mammillaria  are  two  round  white 
bodies,  which  are  formed  by  the  curl  of  the  anterior  crura  of 
the  fornix. 

The  locus  perforatus  posticus,*  is  a  depression  of  grey  matter, 
the  surface  of  which  is  penetrated  by  small  vessels  which  supply 
the  optic  thalami. 

ORIGIN  OF  THE          The  cerebral  nerves  are  given  off  in  pairs,  named 
CEREBRAL  the  first,  second,  third,  &c.,  according  to  the  order 

NERVES.  '  jn  ^hich  they  appear,  beginning  from  the  front. 

*  POES  Tarini. 


DISSECTION    OF    THE    BKAIN. 


595 


There  are  nine  pairs.  Some  are  nerves  of  special  sense — as  the 
olfactory,  the  optic,  the  auditory ;  others  are  nerves  of  common 
sensation — as  the  larger  root  of  the  fifth,  the  glosso-pharyngeal, 
and  the  pneumogastric  ;  others,  again,  are  nerves  of  motion — as 
the  third,  the  fourth,  the  smaller  root  of  the  fifth,  the  sixth,  the 
facial  division  of  the  seventh,  the  spinal  accessory,  and  the  hypo- 
glossal. 

FIG.  145. 


1.  Olfactory  n. 

2.  Optic  n. 

3.  Crus  cerebri. 

4.  Section  of    cms    to 

show  locus  niger. 

6.  Corpus  geniculatum 
externum. 


6.  Corpus  geniculatnm 

internum. 

7.  Corpora        quadri- 

geinina. 

8.  Thalamus  options. 

9.  Tractns  options. 
10.  Corpus  callosum. 


DIAGRAM    OF    THE    ORIGINS    OF    THE   OLFACTORY   AND    OPTIC    NERVES. 


FIRST  PAIR  OR 
OLFACTORY 
NERVES. 


The  olfactory  nerve  is  triangular  on  section,  the 
apex  of  the  triangle  being  lodged  in  a  furrow 
{olfactory  sulcus)  between  the  convolutions.  It 
proceeds  straight  forwards  under  the  frontal  lobe,  and  terminates 
in  the  olfactory  bulb,  which  lies  on  the  cribriform  plate  of  the 
ethmoid  bone. 

The  olfactory  lobe  is  oval,  of  a  reddish-grey  colour,  and  very  soft 
consistence,  owing  to  the  large  amount  of  grey  matter  contained 
in  it.  It  gives  off  from  its  under  surface  about  twenty  branches, 

Q  Q  2 


596  DISSECTION    OF   THE    BRAIN. 

which  pass  through  the  foramina  of  the  cribriform  plate.*  For 
the  description  of  these,  see  p.  233. 

The  nerve  arises  by  three  roots — an  outer  and  an  inner,  com- 
posed of  white  matter,  and  a  middle,  composed  of  grey  (p.  595). 

The  outer  root  passes  forwards  as  a  thin  white  line  from 
the  bottom  of  the  fissure  of  Sylvius,  and  describes  a  curve  with 
the  concavity  outwards.  Its  deeper  origin  has  been  traced  to  the 
optic  thalamus  and  a  nucleus  in  the  anterior  part  of  the  temporo- 
sphenoidal  lobe. 

The  inner  root  arises  from  the  posterior  extremity  of  the  in- 
ternal convolution  of  the  frontal  lobe,  and  thence  may  be  traced  to 
the  gyrus  fornicatus. 

The  middle,  or  grey  root,  arises  from  the  grey  matter  of  the 
sulcus,  in  which  the  nerve  is  lodged,  and  from  the  grey  matter 
of  the  locus  perforatus  anticus;  to  see  it,  therefore,  the  nerve 
should  be  turned  backwards.  It  contains  white  fibres  in  its 
interior,  which  have  been  traced  to  the  corpus  striatum. 

SECOND  PAIR  The  optic  tracts  arise  from  the  corpora  quadri- 

OR  OPTIC.  gemina,  the    corpora   geniculata,    and   the    optic 

thalami  (p.  595).  They  wind  round  the  crura  cerebri,  with  which 
they  are  connected  by  their  anterior  borders,  and  join  in  the 
middle  line  to  form  the  optic  commissure.  This  commissure  rests 
upon  the  sphenoid  bone  in  front  of  the  sella  turcica ;  and  from  it 
each  optic  nerve,  invested  by  its  fibrous  sheath,  passes  through 
the  optic  foramen  into  the  orbit  and  terminates  in  the  retina. 

At  the  commissure  some  of  the  nerve-fibres  cross  from  one  side 
to  the  other.  This  decussation  affects  only  the  middle  fibres  of 

*  Strictly  speaking,  the  olfactory  nerve  and  its  ganglion  are  integral  parts  (the 
prosencephalic  lobe)  of  the  brain.  What  in  human  anatomy  is  called  the  origin  of 
the  nerve  is,  in  point  of  fact,  the  crus  of  the  olfactory  lobe,  and  is  in  every  way  homo- 
logous to  the  crus  cerebri  or  cerebelli.  In  proof  of  this,  look  at  the  enormous  size 
and  connections  of  the  crus  in  animals  which  have  very  acute  sense  of  smell. 
Throughout  the  vertebrate  kingdom  there  is  a  strict  ratio  between  the  sense  of  smell 
and  the  development  of  the  olfactory  lobes.  Again,  in  many  animals,  these  lobes  are 
actually  larger  than  the  cerebral,  and  contain  in  their  interior  a  cavity  which  com- 
municates with  the  lateral  ventricles.  According  to  Tiedemann,  this  cavity  exibts 
even  in  the  human  foetus  at  an  early  period. 


DISSECTION   OP   THE    BRAIN.  597 

the  nerve  ;  the  outer  fibres  pass  from  one  optic  tract  to  the  optic 
nerve  of  the  same  side  ;  the  inner  fibres  pass  from  one  optic  tract 
round  to  the  optic  tract  of  the  opposite  side  ;  while  in  front  of  the 
commissure  are  fibres  which  pass  from  one  optic  nerve  to  its  fellow 
(p.  600).* 

THIRD  PAIR  OR  ^ne  apparent  origin  of  the  third  nerve  is  from 
MOTORES  Ocu-  the  inner  side  of  the  eras  cerebri,  immediately  in 
I.ORUM.  front  of  the  pons.  Some  of  its  roots,  however, 

pass  through  the  locus  niger  and  the  tegmentum  of  the  crus, 
to  reach  a  grey  nucleus  beneath  the  iter  a  tertio  ad  quartum 
ventriculum  and  below  the  corpora  quadrigemina  (p.  595).  It 
passes  through  the  sphenoidal  fissure  and  supplies  all  the  muscles 
of  the  orbit,  except  the  superior  oblique  and  the  rectus  externus. 

FOURTH  PAIR  The  fourth  nerve  arises  from  the  upper  surface 

ORTROCHLEAR  of  the  valve  of  Vieussens  (p.  612).  Here  it 
divides  into  three  sets  of  fibres  :  one,  ascending, 
passes  to  the  roof  of  the  aqueduct  of  Sylvius  ;  another,  decussating, 
passes  over  to  the  opposite  side  to  join  the  ascending  fibres  ;  and 
a  third,  or  descending,  which  rises  from  the  floor  of  the  fourth 
ventricle  close  to  the  locus  cseruleus.  It  runs  obliquely  outwards, 
winds  round  the  crus  cerebri,  enters  the  orbit  through  the  sphe- 
noidal fissure,  and  supplies  the  superior  oblique. 

FIFTH  PAIR  OR  The  fifth  nerve  consists  of  two  roots,  both  of 
which  arise  apparently  from  the  outer  side  of  the 


pons  Varolii  (p.  584)  ;  but  their  real  origin  is 
deeper.  The  smaller  and  anterior  of  the  two  roots,  consisting  of 
motor  fibres  only,  may  be  traced  to  the  outer  side  of  the  fourth 
ventricle,  and  to  a  grey  nucleus  at  the  lower  part  of  the  medulla  ; 
the  posterior  and  larger  root  consisting  of  purely  sensory  fibres, 
may  be  traced  to  a  mass  of  nerve-cells  in  connection  with  the  grey 
tubercle  of  Eolando,  and  also  to  the  middle  of  the  floor  of  the 
fourth  ventricle.  The  nerve  proceeds  forwards  over  the  apex  of 
the  petrous  portion  of  the  temporal  bone  ;  here  is  developed,  upon 

*  This  decussation  was  ingeniously  supposed  by  Dr.  Wollaston  ('Philos.  Trans,  of 
the  Royal  Society,'  1824)  to  account  for  single  vision,  since  the  right  halves  and  the 
left  halves  of  the  eyes  would  derive  their  nerve-fibres  from  the  same  optic  nerve. 


598  DISSECTION    OF   THE    BRAIN. 

the  sensitive  root,  the  Grasserian  ganglion.  The  root  then  divides 
into  three  branches — the  ophthalmic,  which  passes  through  the 
sphenoidal  fissure  ;  the  superior  maxillary,  which  passes  through 
the  foramen  rotundum  ;  the  inferior  maxillary,  which  passes 
through  the  foramen  ovale.  They  all  confer  common  sensation 
upon  the  parts  they  supply,  which  comprises  the  entire  face  and 
sides  of  the  head.  The  small  motor  root  passes  beneath  the 
ganglion,  with  which  it  has  no  connection,  and  accompanies  the 
inferior  maxillary  division,  to  be  distributed  to  the  muscles  of 
mastication. 

SIXTH  PAIR  OR          The  sixth  nerve  emerges  from  the  groove  be- 
ABDUCENTES.  tween  the  pons  and  the  anterior  pyramid  (p.  584), 

with  both  of  which  it  is  connected.  Its  deep  origin  has  been 
traced  to  a  grey  nucleus  of  nerve-cells  in  the  floor  of  the  fourth 
ventricle.  It  leaves  the  skull  through  the  sphenoidal  fissure,  and 
supplies  the  rectus  externus  of  the  eye. 

SEVENTH  PAI  ^e  seventh  comprises  two  nerves — the  portio 

dura,  or  motor  nerve  of  the  face,  and  the  portio 
mollis,  or  auditory  nerve.  The  two  nerves,  of  which  the  portio 
dura  is  the  more  internal  and  anterior,  arise  apparently  from  the 
lower  border  of  the  pons  Varolii  (p.  584).  The  deep  origin  of 
the  portio  dura  is  stated  to  pass  through  the  medulla  to  the  grey 
nucleus  in  the  floor  of  the  fourth  ventricle  near  the  origin  of  the 
sixth  nerve.  The  deep  origin  of  the  portio  mollis  is  from  the 
internal  auditory  nucleus  in  the  floor  of  the  fourth  ventricle.  The 
nerve  then  passes  outwards,  and  enters  the  meatus  auditorius 
internus  in  company  with  the  portio  dura.  For  the  further 
description  of  the  portio  dura,  see  p.  90.  The  auditory  nerve 
divides  at  the  bottom  of  the  meatus  auditorius  internus  into 
cochlear  and  vestibular  branches,  which  are  distributed  to  the 
internal  ear. 

EIGHTH  PAIR  ^is     comprises     three     nerves — the    glosso- 

phai*yngeal,  the  pneumogastric,  and  the  nervus 

accessorius  (p.  580).  The  glosso-pharyngeal  nerve  arises  by  several 

filaments  from  the  restiform  body  of  the  medulla,  through  which 

they   may    be   traced   to    a   grey   nucleus  in  the  outer  part   of 


DISSECTION    OF    THE    BRAIN.  599 

the  floor  of  the  fourth   ventricle,    close  to  the   nucleus    for   the 
vagus. 

The  pneumogastric  nerve  arises  by  numerous  filaments  which 
pass  to  a  grey  nucleus  in  the  floor  of  the  fourth  ventricle,  close  to 
the  middle  line. 

The  nervus  accessorius  is  composed  of  two  parts — an  upper  or 
accessory  portion,  which  arises  from  the  medulla  ;  and  a, lower  or 
spinal  portion,  which  arises  from  the  spinal  cord.  The  accessory 
fibres  may  be  traced  to  the  nucleus  at  the  apex  of  the  calamus 
scriptorius.  The  spinal  portion  arises  by  a  series  of  slender  filaments 
from  the  lateral  tract  of  the  spinal  cord  as  low  down  as  the  fifth  or 
sixth  cervical  vertebra.  The  spinal  portion  ascends  behind  the 
ligamentum  denticulatum,  through  the  foramen  magnum,  into 
the  skull,  and  joins  the  accessory  part.  The  nervus  accessorius 
then  passes  through  the  foramen  j  ugulare  with  the  pneumogastric 
and  glosso-pharyngeal  nerves.  The  glosso-pharyngeal  is  distri- 
buted to  the  mucous  membrane  of  the  pharynx,  and  back  of  the 
tongue  (p.  224).  The  pneumogastric  is  distributed  to  the 
pharynx,  the  larynx,  the  heart  and  lungs,  the  oesophagus,  and 
stomach.  The  nervus  accessorius  supplies  the  sterno-mastoid,  and 
the  trapezius.  For  the  further  description  of  these  nerves,  see 
pp.  225,  226. 

NINTH  PAIR  OB  This  nerve  arises  by  several  filaments  from  the 
HrroGLossAL.  medulla,  along  the  groove  between  the  anterior 
pyramid  and  the  olive.  Its  fibres  may  be  traced  to  a  long  grey 
nucleus,  which  forms  an  eminence  in  the  floor  of  the  fourth  ven- 
tricle in  front  and  to  the  inner  side  of  the  vagal  nucleus.  It 
leaves  the  skull  through  the  anterior  condyloid  foramen,  and  is 
distributed  to  the  muscles  of  the  tongue  and  depressors  of  the  os 
hyoides  and  larynx. 

DISSECTION  OF  The  brain  should  now  be  laid  on  its  base.     By 

gently  separating  the  hemispheres,  we  expose  at 
the  bottom  of  the  longitudinal  fissure  a  white  band  of  nerve-sub- 
stance, which  is  the  great  transverse  commissure  of  the  cerebrum, 
and  termed  the  corpus  callosum. 


600 


DISSECTION   OP   THE    BRAIN. 


Slice  off  the  hemispheres  down  to  the  level  of  the  corpus 
callosum.  The  cut  surface  presents  a  mass  of  white  substance 
WHITE  AND  surrounded  by  a  tortuous  layer  of  grey  matter, 
GREY  MATTER.  about  one-eighth  of  an  inch  in  thickness.  This 
grey  substance  consists  of  four  layers — two  of  grey  alternating 
with  two  of  white,  the  most  external  layer  being  white.  In  some 
places,  chiefly  at  the  base  of  the  brain,  six  layers  have  been 
demonstrated. 


FIG.  146. 


FIG.  147. 


UPPER  SURFACE  OF  COR- 
PUS CALLOSUM. 

1,1.  Linese  transversse. 

2.  Raphe. 

3,  3.  Anterior  cerebral  a. 


DIAGRAM    OF   LAMINA    CINEREA. 


1, 1.  Peduncles  of  corpus  callosum. 

2.  Lamina  cinerea. 

3.  Commissure  of  optic  nerves. 


CORPUS  CALLO- 

SUM. 


This  transverse  portion  of  white  substance  is 
the  chief  connecting  medium  between  the  two 
hemispheres,  and  is  called  the  great  transverse  commissure  of  the 
cerebrum.  It  is  about  four  inches  long,  and  is  rather  nearer  to 
the  front  than  to  the  back  part  of  the  brain.  It  is,  moreover, 
thicker  at  the  ends  than  in  the  middle.  Its  surface  is  slightly 
arched  from  before  backwards.  A  shallow  groove,  called  the 
raphe,  runs  along  the  middle  of  its  upper  surface  (fig.  146)  ;  in  a 


DISSECTION   OF   THE    BRAIN. 


fresh  brain,  two  longitudinal  white  tracts,  named  the  nerves  of 
Landsi,  run  parallel  to  it ;  and  external  to  these  again  are  two 
other  longitudinal  fibres,  stride  longitudinales  later  ales.  The 
surface  of  the  corpus  callosum  is  marked  by  transverse  lines  which 
indicate  the  course  of  its  fibres ;  these  are  the  linece  transversce  of 
the  old  anatomists.  The  anterior  cerebral  arteries  proceed  along 
the  surface  of  the  corpus  callosum  to  the  back  of  the  brain. 

FIG.  148. 


Foramen  of  Monro    . 

Middle  commissure  . 
Anterior  commissure. 
Lamina  cinerea  .  . 


Optic  nerve 


Pituitary  gland 

Infundibulnm 
Tuber  cinereum 
Corpus  mammillare 
Locus  perforatus  posticus 


Tons  Varolii 


Velum  interpositum. 
Thalamus  opticus. 
Pineal  gland. 
Posterior  commissure. 
Nates. 

Iter  a  tertio  ad  qnar- 

tum  ventriculum. 
Valve  of  Vieussens. 

Fourth  ventricle. 


Arachnoid     membrane 
(reflected;. 


Medulla  oblongata 
VERTICAL    SECTION   THROUGH    THE    CORPUS    CALLOSUM,    AND    PARTS    BELOW. 

The  anterior  part  of  the  corpus  callosum  turns  downwards 
and  backwards,  forming  a  bend  called  its  genu.  The  inferior 
part  of  this  bend — rostrum — becomes  gradually  thinner  and 
narrower,  and  terminates  in  two  peduncles,  which  diverge  from 
each  other,  and  are  lost,  one  in  each  fissure  of  Sylvius.  Between 
these  crura  is  placed  the  lamina  cinerea  (fig.  147).  The  posterior 
part  of  the  corpus  callcsum  terminates  in  a  thick,  round  border 
which  is  free,  and  beneath  it  the  pia  mater  enters  the  interior  of 


602  DISSECTION   OP    THE    BRAIN. 

the  ventricles.  A  satisfactory  view  cannot  be  obtained  of  the  arch 
formed  by  the  corpus  callosum,  of  its  terminations  in  front  and 
behind,  and  of  the  relative  thickness  of  its  different  parts,  without 
making  a  perpendicular  section  through  a  fresh  brain,  as  shown  in 
the  preceding  figure.* 

Connected  with  the  under  surface  of  the  posterior  part  of  the 
corpus  callosum  is  the  fornix,  which  separates  from  it  in  front, 
the  two  structures  being  connected  by  a  vertical  septum — the 
septum,  lucidum. 

LATERAL  VEN-  A  longitudinal  incision  should  be  made  on  each 

TRICIJSS.  si(]e  through  the  corpus  callosum  about  half  an 

inch  from  its  median  raphe.  Care  must  be  taken  not  to  cut  too 
near  the  middle  line,  in  order  to  preserve  the  delicate  partition 
which  descends  from  the  under  surface  of  the  corpus  callosum,  and 
separates  the  ventricles  from  each  other.  Two  cavities,  called  the 
lateral  ventricles,  will  thus  be  exposed,  one  in  each  cerebral  hemi- 
sphere, and  they  should  afterwards  be  laid  open  throughout 
their  whole  extent.  Their  general  form  should  be  first  examined ; 
then  the  several  objects  seen  in  them. 

The  lateral  ventricles  are  two  serous  cavities,  one  in  each 
hemisphere  of  the  brain.  They  are  occasioned  by  the  enlargement 
and  folding  backward  of  the  cerebral  lobes  over  the  other  parts  of 
the  central  nervous  axis.  They  contain  a  serous  fluid,  which, 
even  in  a  healthy  brain,  sometimes  exists  in  considerable  quan- 
tity ;  when  greatly  in  excess  it  constitutes  one  form  of  the  disease 
termed  hydrocephalus.  The  ventricles  are  lined  with  ciliated 
epithelium,  laid  upon  a  layer  of  neuroglia  ;  a  term  which  has  been 
applied  to  that  peculiarly  delicate  connective  tissue  found  through- 
out the  brain  and  spinal  cord. 

The  ventricles  are  crescentic  in  shape,  with  their  backs  towards 
each  other.  Each  extends  into  the  three  lobes  of  the  cerebral 
hemisphere,  and  consists  of  a  central  part  or  body,  and  three  horns 
or  cornua,  anterior,  middle,  and  posterior.  The  body,  situated  in 

*  The  corpus  callosum  is  more  or  less  developed  in  all  mammalia,  but  is  absent 
in  birds,  reptiles,  and  fish.  It  has  been  absent  in  the  human  subject  without  any 
particular  mental  de6ciency.  See  cases  recorded  by  Reil,  '  Archiv  fur  die  Phys.'  t.  xi., 
and  Wenzel,  '  De  plenitior.  Struct.  Cereb.'  p.  302. 


DISSECTION    OF    THE    BRAIN. 


603 


the  middle  of  the  hemisphere,  is  separated  from  its  fellow  by  the 
septum  lucid  urn.  Its  roof  is  formed  by  the  corpus  callosum. 
On  the  floor,  beginning  from  the  front,  are  seen,  the  corpus 
striatum,  the  tsenia  semicircularis,  the  optic  thalamus,  the  choroid 
plexus,  and  the  fornix.  The  anterior  horn  extends  into  the 
frontal  lobe,  and  as  it  passes  forwards  it  diverges  slightly  from  its 
fellow  of  the  opposite  side.  Its  roof  is  formed  by  the  corpus 
callosum,  and  it  curves  round  the  anterior  extremity  of  the  corpus 
striatum.  The  posterior  horn  may  be  traced  into  the  occipital 
lobe,  where  it  passes  at  first  backwards  and  outwards,  and  then 
converges  towards  its  fellow.  In  it  are  to  be  noticed  an  elevation 

FIG.  149. 


1.  Corpus  callosum. 

2.  Lateral  ventricle. 

3.  Third  ventricle. 

4.  Corpus  striatum. 

5.  Thalamus  opticus. 


0.  Corpus    marunril- 
lare. 

7.  Choroid  plexus. 

8.  Fornix. 

9.  Pituitary  gland. 


TRANSVERSE    VERTICAL    SECTION    THROUGH    THE    BBAIN. 

of  white  substance,  the  hippocampus  minor,  also  a  triangular  flat 
surface  external  to  it,  called  the  pes  accessorius  or  eminentia 
collateralis* 

The  middle  horn  runs  into  the  middle  lobe,  descends  towards 
the  base  of  the  brain,  making  a  curve,  at  first  backwards  and 
outwards,  then  downwards  and  forwards,  and  lastly  inwards  :  the 

*  The  posterior  horns  are  not  always  equally  developed  in  both  hemispheres,  and 
sometimes  they  are  absent  in  one  or  both. 

In  the  carnivora,  ruminantia,  solipeda,  pachydermata,  and  rodentia,  the  lateral 
ventricles  are  prolonged  into  the  largely  developed  olfactory  lobes.  This  is  the  case 
in  the  humm  foetus  only  at  an  early  period.  • 


604  DISSECTION    OF   THE    BKAIN. 

initial  letters  of  which  make  the  memorial  word  '  bodfi.'  By 
cutting  through  the  substance  of  the  hemisphere,  the  windings  of 
this  horn  can  be  followed ;  in  it  are  the  hippocampus  major,  a 
large  rounded  white  eminence  which  follows  the  -curve  of  the 
cornu ;  the  pes  hippocampi,  the  expanded  paw-like  extremity  of 
the  former ;  the  posterior  cms  of  the  fornix,  the  choroid  plexus, 
and  the  back  of  the  optic  thalamus. 

APPEARANCE  If  a  vertical  transverse  section  were  made  across 

ON  PERPEN-  the   middle   of  the   brain,  the   lateral  ventricles 

DICULA.R  SECTION.  wouid  appear  as  represented  in  fig.  149.  Together 
with  the  third  or  middle  ventricle,  their  shape  slightly  resembles 
the  letter  T.  Such  a  section  shows  well  the  radiating  fibres  of  the 
corpus  callosum,  the  fornix,  and  the  velum  interpositum  beneath 
it ;  also  the  beginning  of  the  transverse  fissure  at  the  base  of 
the  brain,  between  the  crus  cerebri  and  the  temporo-sphenoidal 
lobe. 

The  contents  of  the  lateral  ventricles  should  now  be  examined 
more  in  detail ;  also  the  thin  septum  (septum  lucidum)  by  which 
the  two  lateral  ventricles  are  separated. 

SEPTUM  Luci-  This  is  a  thin  and  almost  translucent  partition 

DUM-  which  descends  vertically  in  the  middle  line  from 

the  under  surface  of  the  corpus  callosum,  and  separates  the 
anterior  part  of  the  lateral  ventricles  from  each  other.  It  is 
attached  above  to  the  corpus  callosum,  below  to  the  reflected  part 
of  the  corpus  callosum  and  fornix  (fig.  148).  It  is  not  of  equal 
depth  throughout.  Its  broadest  part  is  in  front  and  corresponds 
with  the  knee  of  the  corpus  callosum.  It  becomes  narrower 
behind,  tapering  to  a  thin  point,  where  the  corpus  callosum  and 
the  fornix  become  continuous.  The  septum  consists  of  two  layers, 
which  enclose  a  space  called  the  fifth  ventricle  or  the  ventricle  of 
the  septum  (fig.  151).  Each  layer  consists  of  white  substance 
inside,  and  of  grey  outside  ;  the  ventricle  between  them  is  closed 
in  the  adult,  and  lined  with  a  delicate  serous  membrane  ;  but  in 
foetal  life  it  communicates  with  the  third  ventricle  between  the 
pillars  of  the  fornix.* 

*  The  development  of  the  septum  lucidum  commences  about  the  fifth  month  of 


DISSECTION    OF    THE    BEAIN. 


605 


Cut  transversely  through  the  corpus  callosum  and  the  septum 
lucidum,  and  turn  forwards  the  anterior  half.  In  this  way  the 
ventricle  of  the  septum  will  appear,  as  in  fig.  151.  By  turning- 
back  the  posterior  half  of  the  corpus  callosum  a  view  is  obtained 
of  the  fornix.  This  proceeding  requires  care,  or  the  fornix  will 
be  reflected  also,  since  these  two  arches  of  nerve-substance  are 
here  so  closely  connected. 

This  is  a  layer  of  white  matter,  extending  in 
the   form   of    an   arch    from    before    backwards, 
beneath  the  corpus  callosum.     It  is  the  great  longitudinal  com- 
missure, and  lies  over  the  velum  interpositum  (fig.  148,  p.  601). 


1,1.  Corpora  striata. 

2,  2.  Thalami  optici. 

3,  3.  Anterior    crnra 

of  fornix  bend- 
ing down  to  join 
the    corpora 
mammillaria. 


4,  4.  Posterior   crura 

of  the  fornix 
joining  the  hip- 
pocampi. 

5,  5.  Choroid  plexus. 

6,  6.  Hippocampi 

majores. 

7,  Corpus    callosum 

cut  through. 

8,  Ventricle  of  sep- 

tum lucidum. 


DIAGRAM    OF    THE    FORNIX. 

(The  arrow  is  passed  through  the  foramen  of  Monro.) 

Viewed  from  its  upper  surface,  it  is  triangular,  with  the  base 
behind,  as  shown  in  fig.  150.  The  broad  part  or  body  is  con- 
nected with  the  corpus  callosum.  From  its  anterior  narrow  part 
proceed  two  round  white  cords,  called  its  anterior  crura,  one  on 
each  side  of  the  mesial  line.  As  they  pass  forwards,  the  crura 
descend  through  a  mass  of  grey  matter,  towards  the  base  of  the 
brain,  where,  making  a  sudden  bend,  they  form  the  corpora 
mammillaria,  from  which  they  may  be  traced  backwards  and 

foetal  life,  and  proceeds  from  before  backwards,  part  passu  with  the  corpus  callosum 
and  fornix. 


606  DISSECTION    OP   THE    BRAIN. 

upwards,  each  to  the  optic  thalamus  of  its  own  side.  As  they 
descend  the  anterior  crura  are  joined  by  the  peduncles  of  the 
pineal  body  and  by  the  taenia  semicircular  is.  Immediately  behind 
and  below  the  anterior  crura  is  a  passage  through  which  the 
choroid  plexuses  of  opposite  sides  are  continuous  with  each  other. 

FORAMEN  OF         This  aperture  is  called  the  foramen  of  Monro 
MONBO.  (fig.  150).     Strictly  speaking,  it  is  not  a  foramen, 

but  only  a  communication  between  the  two  lateral  and  the  third 
ventricles.  The  posterior  crura  are  continued  downwards  and 
outwards  from  the  body  of  the  fornix  as  thin  flat  white  bands 
intimately  connected  with  the  concave  side  of  the  hippocampus 
major  as  far  down  as  the  pes  hippocampi.  Each  band  is  called 
the  tcenia  hippocampi  or  the  corpus  fimbriatum.* 

The  fornix  should  now  be  cut  through,  and  its  two  portions 
reflected.  On  the  under  surface  of  the  posterior  portion  are  seen 
fibres,  arranged  transversely,  belonging  to  the  corpus  callosum, 
constituting  what  is  termed  the  lyra. 

Between  the  fornix  and  the  upper  surface  of  the  cerebellum 
is  the  transverse  fissure,  or  fissure  of  Bichat,  through  which  the 
pia  mater  enters  the  ventricles.  The  fissure  extends  from  -the 
middle  downwards  on  each  side  to  the  base  of  the  brain,  as  far  as 
the  end  of  the  descending  horn.  It  is  of  a  horse-shoe  shape,  with 
the  concavity  directed  forwards.  The  upper  boundary  of  that 
part  of  the  transverse  fissure  which  extends  into  the  middle  horn 
is  sometimes  called  the  free  margin  of  the  hemisphere. 

CORPUS  STRIA-          This  body  is  so  called  because,  when  cut  into, 
TUM.  it   presents    alternate    layers  of    white   and  grey 

matter.t     It    is    a   much  larger  mass  of  grey  substance  than  it 

*  The  fornix  and  septum  lucidum  are  absent  in  fish  ;  they  are  merely  rudimen- 
tary in  reptiles  and  birds:  but  all  mammalia  have  them  in  greater  or  less  perfection, 
according  to  the  degree  of  development  of  the  cerebral  hemispheres. 

f  The  white  lines  in  the  corpus  striatum  are  produced  by  the  fibres  of  the  crus 
cerebri,  which  traverse  this  mass  of  grey  matter  before  they  expand  to  form  the 
hemisphere.  The  grey  matter  itself  is  sometimes  called  the  anterior  cerebral 
ganglion.  It  is  found  in  all  mammalia,  in  birds,  and,  to  a  certain  extent,  in  reptiles. 
On  a  transverse  section  it  is  triangular,  with  its  base  directed  outwards.  At  this  part 
it  is  divided  by  two  clear  linss  into  three  zones.  Outside  is  a  grey  layer  called  the 
claustrum. 


DISSECTION    OF   THE    BEAIN.  607 

appears  to  be ;  that  which  is  seen  projecting  on  the  floor  of  the 
lateral  ventricle  being  only  a  part  of  it.  The  intra-ventricular 
portion  is  pear-shaped,  broad  in  front,  and  when  traced  backwards 
is  found  to  taper  gradually  to  a  point  on  the  outside  of  the  optic 
thalamus  (p.  605).  The  under  part — extra-ventricular  portion — of 
the  corpus  striatum  lies  embedded  in  the  white  substance  of  the 
hemisphere,  and  corresponds  with  the  island  of  Eeil. 

TJENIA  SEMI-  This   is    a    narrow    semi-transparent    band    of 

CIRCULARIS.  longitudinal  white  fibres,  which  lies  in  the  groove 

between  the  corpus  striatum  and  the  optic  thalamus  (fig.  151). 
In  front,  it  is  connected  with  the  anterior  crus  of  the  fornix  and 
descends  with  it  to  the  corpus  mammillare  ;  behind,  it  is  lost  in 
the  white  substance  of  the  middle  horn  of  the  lateral  ventricle. 
A  vein,  one  or  more  from  the  corpus  striatum,  passes  underneath 
the  taenia  semi-circularis  to  join  the  vena  Galeni. 

HIPPOCAMPUS  This  is  an  elongated  eminence  of  grey  matter, 

MAJQE.  covered  with  white,  and  is  situated  in  the  pos- 

terior part  of  the  descending  horn.  It  extends  to  the  bottom  of 
the  horn,  where  it  becomes  somewhat  expanded,  and  indented  on 
the  surface,  so  as  to  resemble  the  paw  of  an  animal,  whence  its 
name,  pes  hippocampi.  Attached  along  the  front  border  of  the 
hippocampus,  is  the  posterior  crus  of  the  fornix. 

HIPPOCAMPUS  This  eminence,  smaller  than  the  preceding,  is 

MINOR.  situated  in  the  posterior  horn.      It   consists    of 

white  matter  externally,  and  corresponds  to  the  calcarine  fissure. 
Between  the  hippocampus  major  and  minor,  is  a  triangular  smooth 
surface,  called  the  pes  accessorius  or  eminentia  collateralis.  This 
corresponds  to  the  posterior  ramus  of  the  fissure  of  Sylvius. 

VELUM  INTER-  The  velum  interpositum,  which   supports  the 

POSITUM  AND  fornix,  should  now  be  examined.     This  is  a  layer 

CHOHOID  PLEXUS.  of  pja  mater,  which  penetrates  into  the  ven- 
tricles through  the  transverse  fissure,  beneath  the  posterior  border 
of  the  corpus  callosum,  as  shown  in  fig.  150.  The  shape  of  this 
vascular  membrane  is  like  that  of  the  fornix,  and  its  borders 
project  beneath  that  body  and  form  the  red  convoluted  fringes 
called  the  choroid  plexuses.  These  plexuses  consist  almost 


608  DISSECTION    OF   THE    BRAIN. 

entirely  of  tortuous  ramifications  of  minute  blood-vessels,  and 
are  covered  with  vascular  villi.  The  villi  themselves  are  covered 
with  large  spheroidal  epithelial  cells.  In  front,  the  plexuses  com- 
municate with  each  other  through  the  foramen  of  Monro  ;  behind, 
they  descend  into  the  middle  horns  of  the  lateral  ventricles,  and 
become  continuous  with  the  pia  mater  at  the  base  of  the  brain. 
From  the  under  surface  of  the  velum  two  small  vascular  processes 
are  prolonged  into  the  third  ventricle,  forming  the  choroid  plexuses 
of  that  cavity.  Along  the  centre  of  the  velum 

VENJK  (TALENT 

run  two  large  veins,  called  vence  Galeni,  which 
return  the  blood  from  the  ventricles  into  the  straight  sinus. 

The  velum  interpositum,  with  the  choroid  plexuses,  must  now 
be  removed  to  expose  the  following  structures  shown  in  diagram 
(p.  610): — 1.  A  full  view  of  the  optic  thalamus.  2.  Between  the 
optic  thalami  is  the  third  ventricle,  a  deep  vertical  fissure,  situ- 
ated in  the  middle  line.  3.  Behind  the  fissure  is  the  pineal 
body,  a  vascular  structure,  about  the  size  of  a  pea.  From  this 
body  may  be  traced  forwards  two  slender  white  cords,  called  its 
peduncles — one  along  the  inner  side  of  each  optic  thalamus. 
4.  Passing  transversely  across  the  third  ventricle  are  three  com- 
missures— anterior,  middle,  and  posterior,  connecting  the  oppo- 
site sides  of  the  brain.  5.  Immediately  behind  the  pineal  body 
are  four  elevations,  two  on  each  side,  called  the  corpora  quad- 
rigemina,  or  nates  and  testes.  6.  These  bodies  are  connected 
with  the  cerebellum  by  two  bands,  one  on  each  side,  termed  the 
processus  a  cerebello  ad  cerebrum.  7.  Between  these  cords 
extends  a  thin  layer  of  grey  substance,  called  the  value  of 
Vieussens,  beneath  which  lies  the  fourth  ventricle. 

THALAMUS  This,  called  also  the  posterior  cerebral  ganglion, 

OPTICUS.  is   the   oval  elevation  seen  on  the   floor   of  the 

lateral  ventricle,  immediately  behind  the  corpus  striatum  and 
tsenia  semicircularis.  The  under  surface  rests  upon  its  correspond- 
ing crus  cerebri,  and  forms  the  roof  of  the  middle  horn  of  the 
lateral  ventricle.  Though  white  on  the  surface,  its  interior  con- 
sists of  alternate  layers  of  white  and  grey  matter.  Beneath  the 
posterior  part  of  the  thalamus  are  two  small  eminences,  termed  the 


DISSECTION    OP    THE    BRAIN.  609 

corpora,  geniculata,  intemum  and  externum.  These  consist  of 
small  accumulations  of  grey  matter,  beneath  the  white  ;  one  being 
situated  to  the  outer,  the  other  to  the  inner  side  of  the  optic  tract, 
fig.  145.  A  narrow  band  of  white  substance  connects  the  external 
one  with  the  nates,  and  a  similar  band  connects  the  internal  one 
with  the  testes.* 

THIRD  YEN-  This  is  the  narrow  fissure    between   the  optic 

TRICLE.  thalami,  and  reaches  down  to  the  base  of  the  brain. 

Its  roof  is  formed  by  the  velum  interpositum  and  fornix ;  the  floor, 
which  increases  in  depth  in  front,  is  formed  by  certain  parts  at  the 
base  of  the  brain,  found  within  the  interpeduncular  space — viz., 
the  locus  perforatus  posticus,  corpora  mammillaria,  tuber  cinereum, 
infundibulum,  and  lamina  cinerea,  all  of  which  are  best  seen  in  a 
vertical  section,  as  shown  p.  601.  In  front,  it  is  bounded  by 
the  anterior  crura  of  the  fornix,  and  the  anterior  commissure; 
laterally,  by  the  optic  thalami  and  the  peduncles  of  the  pineal 
body  ;  behind,  it  communicates  with  the  fourth  ventricle  through 
the  Her  a  tertio  ad  quartum  ventriculum,  which  is  a  long  canal 
beneath  the  corpora  quadrigemina. 

Passing  across  the  third  ventricle  are  seen  three 

COMMISSURES.  .  . 

commissures,  the  anterior,  middle,  and  posterior. 
The  middle  commissure  may  be  seen  by  gently  separating  the 

optic  thalami,  and  is  about  half  an  inch  in  breadth. 

This  is  composed  entirely  of  grey  substance,  and 
in  most  brains,  owing  to  its  softness,  is  generally  torn  before  it 
can  be  examined. f  The  anterior  commissure  is  a  round  white 

cord,   which    lies   immediately   in    front   of  the 

anterior  crura  of  the  fornix,  and  connects  the 
corpora  striata.  This  commissure  may  be  traced  on  each  side, 
through  the  corpora  striata,  extending  backwards  far  into  the 

*  These  bands  are  faintly  marked  in  man,  but  are  more  apparent  in  the  lower 
animals. 

f  The  soft  commissure  does  not  appear  to  be  a  very  essential  constituent  part  of 
the  brain.  It  is  not  found  before  the  ninth  month  of  foetal  life ;  and  in  some  in- 
stances, according  to  our  observations,  is  never  developed.  Wenzel  states  that  it  is 
absent  in  about  one  out  of  seven  subjects  ('  De  plenitiori  Struct.  Cerebri  Horn,  et 
Brut.'  Tubingen,  1812). 

B  R 


610 


DISSECTION    OF    THE    BEAUT. 


temporo-sphenoidal  lobes.     Situated  immediately  in  front  of  and 
rather  below  the  pineal  body  is  another  thin  round 

POSTERIOB.  . 

white  cord  called  the  posterior  commissure.  Its 
fibres  pass  into  the  substance  of  the  hemisphere  and  connect  the 
optic  thalami. 

The  third  ventricle  communicates  with  the  lateral  ventricles 


Corpus  callosum  cut  through  .    . 

Ventricle  of  the  septum  lucidum  . 

Corpus  striatum 

Anterior  crura  of  the  fornix     .     . 

Anterior  commissure 

Tsenia  semicircularis 

Middle  commissure 

Thalamns  opticus 

Crura  of  pineal  gland 


Posterior  commissure  , 
Pineal  gland  .     .     . 
Nates 


Testes 

Valve  of  Vieussens 

Processus  a  cersbello  ad  cerebrum 


through  the  foramen  of  Monro,   and   with   the  fourth   ventricle 
through  the  iter  a  tertio  ad  quartum  ventriculum. 

PINEAL  BODY,  This  vei7  vascular  oval  body  is  situated  immedi- 

OE  GLANP.  ately  in  front  of  the  corpora  quadrigemina  (fig.  151). 

It  is  firmly  connected  with  the  under  surface  of  the  velum,  and  is 
apt  to  be  separated  from  its  normal  position  when  that  membrane  is 


DISSECTION    OF    THE    BRAIN.  611 

reflected.  It  is  about  the  size  of  a  cherry-stone,  and  has  two  white 
peduncles  or  crura,  which  extend  forwards,  one  on  the  inner  side 
of  each  optic  thalamus,  and  terminate  by  joining  the  anterior 
crura  of  the  fornix.  These  crura  are  connected  together  behind, 
and  with  the  front  of  the  posterior  commissure.  In  its  interior  it 
contains,  besides  some  viscid  fluid,  more  or  less  gritty  matter, 
consisting  of  phosphate  and  carbonate  of  lime. 

Although  the  pineal  body  is  found  in  all  mammalia,  birds, 
and  reptiles,  in  the  same  typical  position,  its  functions  are  entirely 
unknown. 

COEPOBA  QUAD-         These  are  four  eminences,  situated,  two  on  each 
RIGEMINA.  side,  behind  the  pineal  body,  and  are  separated 

from  each  other  by  a  crucial  depression.  Laterally,  they  are  con- 
nected with  the  optic  thalami  and  crura  cerebri,  and  are  placed 
above  the  iter  a  tertio  ad  quartum  ventriculum.  Though  white 
on  the  surface,  they  contain  grey  matter  in  the  interior  for  the 
purpose  of  giving  origin  to  the  optic  tract.  A  more  appropriate 
term  for  them  would  be  the  '  optic  lobes,'  instead  of  '  nates  and 
testes,'  handed  down  from  the  old  anatomists.  The  nates,  the 
more  anterior,  are  rather  darker  and  larger  than  the  testes  :  and 
from  both  proceed  outwards  two  flat  white  cords,  the  anterior  and 
posterior  brachia.  The  anterior  proceeds  to  the  optic  tract,  optic 
thalamus  and  corpus  geniculatum  externum,  the  posterior  to  the 
crus  cerebri  and  corpus  geniculatum  internum.* 

PROCESSUS  A  CE-  By  gently  drawing  back  the  overlapping  cere- 
RKBEIXO  AD  CERE-  bellum,  two  broad  white  cords  are  seen,  which 
pass  backwards,  diverging  from  each  other,  from 
the  corpora  quadrigemina  to  the  cerebellum  (fig.  151).  These 
are  the  processus  a  cerebello  ad  cerebrum,  or  superior  peduncles 
of  the  cerebellum.  They  connect  the  cerebrum  and  cerebellum, 

*  Eminences  homologous  to  the  corpora  quadrigemina  are  found  in  all  vertebrate 
animals ;  they  are  the  meso-cephalic  lobea ;  they  always  give  origin  to  the  optic 
nerves,  and  their  size  bears  a  direct  relation  to  the  power  of  sight.  They  are  rela- 
tively smaller  in  man  than  in  any  other  animal.  In  birds  there  are  only  two 
eminences,  and  these  are  very  large,  especially  in  those  far-seeing  birds  which  fly 
high,  as  the  eagle,  falcon,  vulture,  &c.,  who  require  acute  sight  to  discern  their  prey 
at  a  distance. 

RR2 


612  DISSECTION    OF    THE    BRAIN. 

and  rest  upon  the  crura  cerebri.  The  space  between  them  is 
occupied  by  a  thin  layer  of  grey  matter,  which  covers  the  fourth 
ventricle.  This  layer  is  called  the  valve  of  Vieussens,  is  narrow 
in  front,  and  broad  posteriorly,  where  it  is  connected  with  the  cen- 
tral portion  of  the  cerebellum. 

The  third  ventricle  is  connected"  with  the 
AD  QUARTUM  VKN-  fourth  .by  a  canal  large  enough  to  admit  a 
TBICUIUM  OK  probe,  which  runs  backwards  beneath  the  pos- 

AQUEDUCT  OF  terior  commissure  and  the  corpora  quadrigemina 

(p.  601).  This  passage,  together  with  the  third 
and  fourth  ventricles,  are  persistent  parts  of  the  central  canal 
which  in  early  foetal  life-  extended  down  the  middle  of  the  cerebro- 
spinal  axis.  It  subsequently  becomes  much  encroached  upon  by 
the  large  increase  of  grey  substance,  and  in  its  floor  are  seen  the 
nuclei  common  to  the  third  and  fourth  nerves  of  each  side. 

FOURTH  VBN-  This  space  is  situated  between  the  cerebellum 

TRICLE.  and  the  posterior  part  of  the  medulla  oblongata 

and  pons  Varolii.  It  is  only  a  dilated  portion  of  the  primordial 
canal  alluded  to  in  the  last  paragraph.  To  obtain  a  perfect  view 
of  its  boundaries,  a  vertical  section  should  be  made,  as  in  diagram 
(p.  601).  It  appears  triangular,  and  its  boundaries  are  as  follows  : 
— The  front  or  base  is  formed  by  the  medulla  oblongata  and  pons 
Varolii ;  the  upper  wall  by  the  valve  of  Vieussens  and  the  aqueduct 
of  Sylvius ;  the  posterior  wall  by  the  inferior  vermiform  process 
of  the  cerebellum  ;  below,  by  the  continuation  of  the  arachnoid 
membrane  on  to  the  spinal  cord ;  and,  laterally,  by  the  processus 
a  cerebello  ad  cerebrum,  posterior  pyramids,  and  restiform  bodies. 
The  pia  mater  is  prolonged  for  a  short  distance  into  the  lower 
part  of  the  cavity,  and  forms  the  choroid  plexus  of  the  fourth 
ventricle.* 

The  anterior  wall  of  the  fourth  ventricle  is  lozenge-shaped, 
and  on  it  are  the  following  objects,  which  should   be   separately 

*  Tiedemann  proposed  to  call  the  fourth  ventricle  the  first :  because  in  the  foetus, 
it  is  formed  sooner  than  any  of  the  others ;  because  it  exists  in  all  vertebrated 
animals,  whereas  the  lateral  ventricles  are  absent  in  all  osseous  fishes ;  and  because 
the  ventricle  of  the  septum  lucidum  is  absent  in  all  fishes,  in  reptiles,  and  in  birds. 


DISSECTION    OF    THE    BRAIN.  613 

examined  (p.  585): — 1.  A  median  groove,  the  remains  of  the 
primitive  axis  canal ;  running  parallel  to  it  on  each  side  is  a 
round  elevation,  the  fasciculus  teres.  2.  From  the  lower  part  of 
the  furrow  two  white  cords  (the  restiform  bodies  or  inferior 
crura  cerebelli)  pass  off  from  the  medulla  oblongata,  diverging 
like  the  branches  of  the  letter  V.  and  enter  the  lateral  hemi- 
spheres of  the  cerebellum.  The  divergence  of  these  cords,  with 
the  median  furrow,  was  called  by  the  old  anatomists  the  calamus 
scriptorius.  3.  The  floor  of  the  fourth  ventricle  is  covered  by 
grey  matter,  which  is  the  grey  substance  of  the  medulla  exposed 
.  by  the  divergence  of  the  restiform  bodies ;  one  slight  accumula- 
tion, external  to  the  fasciculus  teres,  has  received  the  name  of  locus 
cceruleus.  4.  On  the  floor  are  seen  a  number  of  transverse  white 
lines — striae  medullares — emerging  from  the  median  groove, 
some  of  which  form  part  of  the  origin  of  the  auditory  nerves. 
c  This  portion  of  the  brain  is  situated  in  the 

occipital  fossa,  beneath  the  posterior  lobes  of  the 
cerebrum,  from  which  it  is  separated  by  the  tentorium.  Its  form 
is  ellipsoidal,  with  the  long  axis  transverse.  When  the  arachnoid 
membrane  and  the  pia  mater  are  removed,  it  is  noticed  that  its 
surface  is  darker,  and  not  arranged  in  convolutions  like  those  of 
the  cerebrum.  It  consists  of  a  multitude  of  thin  plates,  folia, 
disposed  in  a  series  of  concentric  curves,  with  the  concavity 
forwards.  By  a  little  dissection,  it  is  easy  to  separate  some  of 
the  laminae  from  each  other,  and  to  see  that  the  intervening 
fissures  increase  in  depth  from  the  centre  towards  the  circum- 
ference. 

The  cerebellum  consists  of  two  lateral  hemispheres  united  by 
an  intermediate  portion,  the  vermiform  process,  the  upper  aspect 
of  which  takes  the  name  of  the  superior  vermiform  process,  the 
inferior  that  of  the  inferior  vermiform  process.  Comparative 
anatomy  proves  that  this  is  the  fundamental  part  of  the  cere- 
bellum, the  lateral  masses  not  being  developed  in  the  vertebrate 
series  until  after  the  birds.  In  man  they  form  by  far  the  largest 
part  of  the  cerebellum. 

The  upper  surface  is  divided  from  the  lower  by  a  deep  fissure, 


614  DISSECTION    OP    THE    BEAIN. 

named  the  great  horizontal,  which  extends  along  the  free  border 
of  each  hemisphere. 

UPPER  SUB-  The  upper  surface  of  the  cerebellum  slopes  on 

FACB-  each  side,  having  a  ridge  along  the  middle  line, 

called  the  superior  vermiform  process.  This  process  presents 
three  eminences,  an  anterior,  middle,  and  posterior,  which  are 
named  respectively,  the  lobulus  centralis,  the  monticulus  cere- 
belli, and  the  commissura  simplex.  The  hemispheres  are  sepa- 
rated posteriorly  by  a  deep  notch,  the  incisura  cerebelli  posterior, 
which  receives  the  falx  cerebelli.  On  this  surface  of  the  cerebel- 
lum are  two  lobes,  one  of  which,  the  quadrate,  is  situated  on  its 

FIG.  152. 


pi 

SUPERIOR    SURFACE    OF    THE    CEREBELLUM. 

ics.  Insisura  cerebelli  anterior.  p  i.  The  posterior  inferior  lobe. 

ic  p.  Incisura  cerebelli  posterior.  hf.  The  great  horizontal  fissure. 

a  s  or   lq.  The  anterior  superior  or  quadrate  I  c.  The  lobulus  centralis. 

lobe.  m  c.  Monticulus  cerebelli. 

p  s.  The  posterior  superior  lobe.  c  s.  Commissura  simplex. 

external  and  anterior  aspect,  the  other,  the  posterior,  is  placed 
along  its  posterior  border. 

UNDER  SUB-  0Q  the   under  surface  of  the  cerebellum,  its 

FACE.  division    into   two   hemispheres    is    clearly    per- 

ceptible. The  deep  furrow  between  them  is  called  the  vallecula. 
The  front  part  of  it  is  occupied  by  the  medulla  oblongata.  To 
examine  the  surface  of  the  valley  the  medulla  must  be  raised, 
and  the  hemispheres  separated  from  each  other.  Along  the 
middle  line  of  the  vallecula  is  the  inferior  vei^miform  process. 


DISSECTION    OP    THE    BRAIN.  615 

which  is  the  under  surface  of  the  fundamental  part  of  the  cere- 
bellum. Traced  forwards,  this  process  terminates  in  the  nodule ; 
traced  backwards,  it  ends  in  a  small  conical  projection,  called 
the  pyramid ;  between  these  is  a  tongue-like  body,  called  the 
uvula. 

Each  hemisphere  presents  on  its  under  surface  certain  secondary 
lobes,  to  which  different  names  have  been  applied  (fig.  153). 
That  portion  which  immediately  overlies  the  side  of  the  vallecula 
is  called  the  tonsil  (amygdala) ;  this  is  connected  with  the 
uvula  by  an  indented  layer  of  grey  matter,  called  the  furrowed 

FIG.  153. 


INFERIOR    SURFACE    OF    THE    CEREBELLUM. 

A.  The  amygdala.  /  I.  The  flocculus. 

Bi.  The  biventral  lobe.  n.  The  nodule      \ 

G.  The  slender  lobe.  «.  The  uvula        I  situated  in  the  vallecula. 

H.  Th«  posterior  inferior  lobe.  p.  The  pyramid  ) 

hf.  The  great  horizontal  fissure. 

band.     At  the  anterior  part  of  each  hemisphere,  near  the  middle 
line,  is  a  little  lobe  named  the  flocculus  or  subpeduncular  lobe. 

From  either  side  of  the  uvula  may  be  traced  a  thin  valve-like 
fold  of  white  substance,  which  proceeds  in  a  semicircular  direc- 
tion to  the  flocculi.  These  folds  form  the  posterior  medullary 
velum*  To  see  this  satisfactorily,  the  tonsils  must  be  carefully 
separated  from  each  other. 

*  These  are  sometimes  called  the  valves  of  Tarini. 


616  DISSECTION    OF    THE    BRAIN. 

In  addition  to  the  amygdalae  and  flocculi,  already  mentioned, 
other  lobes  have  been  described  on  the  under  surface  of  the  cere- 
bellum. Thus,  there  is  the  digastric  lobe,  situated  external  to  the 
amygdala ;  and  behind  this  are  successively  the  slender  and  the 
posterior  inferior  lobes. 

PEDUNCLES  OF  The  cerebellum  is   connected  with  the  cerebro- 

THK  CEREBELLUM,  spinal  axis  by  three  peduncles  or  crura — a  superior, 
middle,  and  inferior.  With  the  medulla  oblongata  it  is  connected 
by  means  of  the  restiform  tracts  ;  these  are  called  the  processus 
a  cerebello  ad  medullam,  or  its  inferior  peduncles ;  with  the 
cerebrum  it  is  connected  by  means  of  the  processus  e  cerebello  ad 
cerebrum  ;  these  are  called  its  superior  peduncles.  The  lateral 
portions  of  the  pons  constitute  its  middle  peduncles. 

INTERNAL  To  examine  the  internal  structure  of  the  cere- 

STRUCTURK,  bellum,   a   longitudinal    section   must    be   made 

through  the  thickest  part  of  one  of  its  hemispheres.  There  is 
then  seen  in  the  centre  a  large  nucleus  of  white  substance,  from 
which  branches  radiate  into  the  grey  substance  in  all  directions. 
Each  of  these  branches  corresponds  to  one  of  the  folia  of  the 
cerebellum,  and  from  it  other  smaller  branches  proceed  and  again 
subdivide.  This  racemose  arrangement  of  the  white  matter  in 
the  substance  of  the  grey  has  been  likened  to  the  branches  of  a 
tree  deprived  of  its  leaves,  and  is  generally  known  as  the  arbor 
vitce. 

CORPUS  DEN-  In  the  centre  of  the  white  substance  of  each 

TATUM-  hemisphere  is  a  nucleus  of  grey  matter,  the  corpus 

dentatum.,  consisting  of  a  zigzag  line  of  yellowish-grey  colour,  in- 
complete at  its  upper  and  inner  part,  and  enclosing  within  it  some 
white  substance.  From  its  centre  white  fibres  may  be  traced  to 
the  superior  cerebellar  peduncles  and  the  valve  of  Vieussens.  It 
is  displayed  either  by  a  vertical  or  by  a  horizontal  section. 

Kespecting  the  function  of  the  cerebellum,  the 
FUNCTIONS.  ••    i      ,  •  j    r  .• 

deductions   derived   irom    comparative    anatomy 

and  physiological  experiments  render  it  probable  that  it  is  the 
co-ordinator  of  muscular  movements — e.g.^  in  walking,  flying,  and 
swimming. 


617 


DISSECTION   OF  THE  SPINAL  CORD. 

To  examine,  in  situ,  the  spinal  cord  covered  with  its  mem- 
branes, the  arches  of  the  vertebrae  must  be  sawn  through,  and 
removed.  It  is  then  noticed  that  the  cord  does  not  occupy  the 
whole  cavity  of  the  spinal  canal.  The  dura  mater  does  not  adhere 
to  the  vertebrae,  and  does  not  form  their  internal  periosteum,  as  in 
the  skull.  Between  the  bones  and  this  membrane,  a  space  inter- 
venes, which  is  filled  with  a  soft  reddish-looking  fat,  with  watery 
cellular  tissue,  and  the  ramifications  of  a  plexus  of  veins. 

FIG.  154. 


1.  Anterior  external  4lOr.ii1'' "'  '^liByl  \       ««  3-  Posterior  longitudinal 

veins.  JK~±!iillLM  II  spinal  vein,. 

2.  Posterior  external           (]F':  ''•'..'     ATO^A^KVv.BB  4-  Anterior    longitudinal 

veins.                             m^'::^MU^^^ii  spinal  veins. 


*         3 
DIAGRAM  OF  THE  SPINAL  VEINS.     (Vertical  section.) 

SPINAL  SYSTEM         The  spine  is  remarkable  for  the  number  of  large 
OF  VEINS.  and  tortuous  veins  which  ramify  about  it,  inside 

and  outside  the  vertebral  canal  (fig.  154).*  There  are — 1.  The 
posterior  external  veins  which  form  a  tortuous  plexus  outside 
the  arches  and  spinous  processes  of  the  vertebrae ;  they  send  off 
branches,  which  pass  through  the  ligamenta  subflava,  and  end 
in  the  plexus  inside  the  vertebral  canal.  2.  The  veins  of 
the  bodies  of  the  vertebrce  emerge  from  the  backs  of  the  bodies, 
and  empty  themselves  into  —  3.  the  anterior  longitudinal 
spinal  veins ;  these,  two  in  number,  one  on  each  side,  are  the 

*  Vide  Breschet,  'Essai  sur  les  Veines  du  Rachis,'  4to. ;  '  Traite  Anatomique  sur 
le  Systeme  Veineux,  fol.  avec  planches,'  1829;  also  Cloquet,  'Traite  d'Anatomie 
descriptive.' 


618 


DISSECTION    OF    THE    SPINAL    CORD. 


large  tortuous  veins  which  extend  down  the  spinal  canal,  behind 
the  bodies  of  the  vertebrae.  4.  The  posterior  longitudinal 
spinal  veins,  like  the  anterior,  run  along  the  whole  length 
of  the  spinal  canal.  They  form  a  tortuous  venous  plexus, 
situated  inside  the  vertebral  arches,  and  communicate  with  the 
anterior  longitudinal  veins  by  cross  branches  at  frequent  intervals. 
5.  The  proper  veins  of  the  spinal  cord  lie  within  the  dura  mater. 
They  form  a  fine  plexiform  arrangement  of  veins  over  both  sur- 
faces of  the  cord,  and  can  with  difficulty  be  injected  from  the 
other  spinal  veins.  This  complicated  system  of  veins  dis- 
charges itself  through  the  intervertebral  foramina  in  the  several 

FIG.  155. 


1.  Anterior  external 

veins. 

2.  Posterior  external 

veins. 

3.  Posterior  longitudinal 

spinal  veins. 


4.  Anterior  longitudinal 

spinal  veins. 

5.  Internal  veins  of  the 

body  of  the  vertebra. 

6.  Lateral  veins. 


DIAGRAM  OF  THE  SPINAL  VEINS.     (Transverse  section.) 

regions  of  the  spine,  as  follows  : — In  the  cervical,  into  the  vertebral 
veins ;  in  the  dorsal,  into  the  intercostal  veins  ;  in  the  lumbar, 
into  the  lumbar  veins.  None  are  provided  with  valves  :  hence  they 
are  liable  to  become  congested  in  diseases  of  the  spine. 

The  membranes  of  the  spinal  cord,  though  continuous  with 
those  of  the  brain,  differ  from  them  in  certain  respects,  and  require 
separate  notice. 

The  dura  mater  of  the  cord  is  a  tough  fibrous 
membrane  like  that  of  the  brain,  but  does  not 
adhere  to  the  bones,  being  separated  from  them  by  fat,  loose 
areolar  tissue,  and  the  plexus  of  veins  described  above.  Moreover, 
such  adhesion  would  impede  the  free  movement  of  the  vertebrae 


DURA  MATER. 


DISSECTION    OP    THE    SPINAL    CORD.  619 

upon  each  other.  It  is  attached  firmly  above  to  the  margin  of  the 
foramen  magnum,  and  may  be  traced  downwards  as  a  sheath  as  far 
as  the  second  bone  of  the  sacrum,  from  which  it  is  prolonged  as  a 
cord  to  the  coccyx,  where  it  becomes  continuous  with  the  peri- 
osteum. It  forms  a  complete  canal  or  bag,  which  surrounds  loosely 
the  spinal  cord,  and  sends  off  a  prolongation  over  the  trunk  of 
each  spinal  nerve.  These  prolongations  accompany  the  nerves  only 
as  far  as  the  intervertebral  foramina,  and  are  then  blended  with 
the  periosteum. 

Cut  through  the  nerves  which  proceed  from  the  spinal  cord  on 
each  side,  and  remove  the  cord  with  the  dura  mater  entire.     Then  - 
slit  up  the   dura  mater  along  the  middle  line,  to  examine  the 
arachnoid  membrane. 

ARACHNOID  The  arachnoid  membrane  of  the  cord  is  a  con- 

MEMBHANE.  tinuation  from   that   of  the   brain,  and,  like  it, 

consists  of  a  visceral  layer,  which  surrounds  the  cord,  and  a 
parietal,  which  lines  the  inner  surface  of  the  dura  mater.  The 
visceral  layer  is  not  in  immediate  contact  with  the  pia  mater 
beneath  it,  but  is  separated  from  it  by  a  transparent  watery  fluid 
contained  in  the  meshes  of  the  subarachnoid  tissue  (p.  579.) 

CEREBRO-  This   cerebro-spinal   fluid    cannot   be    demon- 

SPINAL  FLUID.  strated  unless  the  cord  be  examined  very  soon  after 
death,  and  before  the  removal  of  the  brain.*  The  nerves  proceed- 

*  The  existence  and  situation  of  the  cerebro-spinal  fluid  were  first  discovered  by 
Haller,  '  Element.  Phys.'  vol.  iv.  p.  87,  and  subsequently  more  minutely  investigated 
by  Magendie,  'Kecherches  Phys.  et  Cliniques  sur  le  Liquide  Cephalo-rachidien,'  in 
4to.  avec  atlas:  Paris,  1842.  This  physiologist  has  shown  that  if,  during  life,  the 
arches  of  the  vertebrae  are  removed  in  a  horse,  dog,  or  other  animal,  and  the  dura 
mater  of  the  cord  punctured,  there  issue  jets  of  a  fluid  which  had  previously  made  the 
sheath  tense.  The  fluid  communicates,  through  the  fourth  ventricle,  with  that  in  the 
general  ventricular  cavity.  The  collective  amount  of  the  fluid  varies  from  1  to  2  oz. 
or  more.  It  can  be  made  to  flow  from  the  brain  into  the  cord,  or  vice  versd.  This  is 
proved  by  experiments  on  animals,  and  by  that  pathological  condition  of  the  spine  in 
children  termed  'spina  bifida.'  In  the  latter  instance,  coughing  and  crying  make  the 
tumour  swell ;  showing  that  fluid  is  forced  into  it  from  the  ventricles.  Again,  if 
pressure  be  made  on  the  tumour  with  one  hand,  and  the  fontanelles  of  the  child 
examined  Mith  the  other,  in  proportion  as  the  spinal  swelling  decreases  so  is  the 
brain  felt  to  swell  up,  accompanied  by  symptoms  resulting  from  pressure  on  the 


620  DISSECTION   OF    THE    SPINAL   CORD. 

ing  from  the  cord  are  loosely  surrounded  by  a  sheath  of  the  arach*? 
noid ;  but  this  only  accompanies  them  as  far  as  the  dura  mater, 
and  is  then  reflected  upon  that  membrane. 

The  pia  mater  of  the  cord  is  the  protecting 
membrane,  which  immediately  invests  it.  It  is 
very  different  in  structure  from  that  of  the  brain,  since  it  does 
not  constitute  a  membrane  in  which  the  arteries  break  up,  but 
serves  rather  to  support  and  strengthen  the  cord  :  consequently, 
it  is  much  less  vascular,  more  fibrous  in  its  structure,  and  more 
adherent  to  the  substance  of  the  cord.  It  sends  down  thin  folds 
into  the  anterior  and  posterior  median  ns"sures  of  the  cord,  and  is 
prolonged  upon  the  spinal  nerves,  forming  their  investing  mem- 
brane or  '  neurilemma.' 

Over  the  anterior  median  fissure  may  be  traced  a  well-marked 
fibrous  band,  formed  by  the  pia  mater,  which  has  been  named  the 
linea  splendens. 

Below  the  level  of  the  second  lumbar  vertebra,  the  pia  mater 
is  continued  as  a  slender  filament,  called  the  filum  terminate,  or 
central  ligament,  which  runs  down  in  the  middle  of  the  bundle 
of  nerves  into  which  the  spinal  cord  breaks  up.  About  the  level 
of  the  third  sacral  vertebra  it  becomes  continuous  with  the  dura 
mater  of  the  cord,  and  is  then  prolonged  as  far  as  the  base  of 
the  coccyx.  The  spine  of  the  third  sacral  vertebra  marks  the  level 
to  which  the  cerebro-spinal  fluid  descends  in  the  vertebral  canal. 

LIQAMENTUM  From   each   side   of  the  cord  along  its  whole 

DENTICULATUM.  length  there  runs  a  fibrous  band,  lig ' amentum 
denticulatum,  which  gives  off  a  series  of  processes  to  steady  and 
support  the  cord.  They  are  triangular,  their  bases  being  attached 
to  the  cord,  and  their  points  to  the  inside  of  the  dura  mater 
(fig.  156).  There  are  from  eighteen  to  twenty-two  of  them  on 
each  side,  and  they  lie  between  the  anterior  and  posterior  roots  of 
the  spinal  nerves.  The  first  process  passes  between  the  vertebral 
artery  and  the  hypoglossal  nerve ;  the  last  is  found  at  the  ter- 
mination of  the  cord.  It  is  composed  of  fibrous  tissue,  and  is 

nervous  axis  generally.  See  some  remarks  very  much  to  the  point,  by  Sir  George 
Burrows,  '  On  Diseases  of  the  Cerebral  Circulation,'  p.  50,  1846. 


DISSECTION    OP    THE    SPINAL    COED. 


621 


SPINAL  CORD. 


FIG.  156. 


DIAGRAM   OF    THE     LIGAMENTUM 
DENTICTTLATUM. 


enticuiatum. 


covered  with  nucleated  cells  continuous  with  the  arachnoid  mem- 
brane.* 

The  spinal  cord  is  that 
part  of  the  cerebro-spinal 
axis  contained  in  the  vertebral  canal. 
It  is  the  continuation  of  the  medulla 
oblongata,  and  extends  from  the  fora- 
men magnum  down  to  the  upper  border 
of  the  second  lumbar  vertebra,  where 
it  terminates  in  a  conical  point,  conus 
medullaris,  after  having  given  off  the 
large  bundle  of  nerves  termed  cauda 

equina,    for    the     Supply 
CAUDA  EQUINA.        *  rr 

oi  the  lower  limbs,  r  rom 

the  conus  medullaris  there  is  continued 
downwards  a  slender  cord,  the/Hum  terminale,  which  passes  within 
the  sheath  to  the  coccyx.  f  The  length  of  the  cord  is  from  fifteen 
to  eighteen  inches,  and  its  general  form  is  '  cylindrical,  slightly 
flattened  in  front  and  behind.  It  is  not  of  uniform  dimensions 
throughout.  It  presents  a  considerable  enlargement  in  the  lower 
part  of  the  cervical  region  ;  another  in'  the  lower  part  of  the 
dorsal,  from  which  proceed  the  large  nerves  to  the  upper  and 
lower  limbs,  respectively.  The  upper  or  cervical  enlargement, 
which  is  the  larger,  extends  from  the  third  cervical  to  the 
first  dorsal  vertebra  ;  the  lower,  or  lumbar,  is  situated  opposite 
to  the  last  dorsal  vertebra.  J 

The  cord  is  divided  into  two  symmetrical  halves 
by  a  median  longitudinal  fissure   in   front    and 
behind  (fig.  157).     The  anterior  fissure  is  the  more  distinct,  and 


Dura  mater. 
2,  2. 


FISSURES. 


*   Vide  Axel,  Key,  and  Eetzius;  Max  Schultze's  'Archives,'  1873. 

t  The  explanation  of  this  is,  that,  at  an  early  period  of  foetal  life,  the  length  of 
the  cord  corresponds  with  that  of  the  vertebral  canal ;  but  after  the  third  month,  the 
lumbar  and  sacral  vertebrae  grow  away  from  the  cord,  in  accordance  with  the  more 
active  development  of  the  lower  limbs.  See  Tiedemann,  '  Anatomie  und  Bildungs- 
geschichte  des  Gehirns  im  Foetus  des  Menschen,'  &c.;  Nuremberg,  1816. 

J  In  very  early  foetal  life  these  enlargements  do  not  exist,  and  only  make  their 
appearance  with  the  development  of  the  extremities. 


622 


DISSECTION   OP    THE    SPINAL    COED. 


penetrates  about  one-third  of  the  substance  of  the  cord.  It  con- 
tains a  fold  of  pia  mater,  with  many  blood-vessels  for  the  supply 
of  its  interior.  At  the  bottom  of  this  fissure  is  a  transverse 
layer  of  white  substance,  named  the  anterior  white  commissure, 
connecting  the  two  anterior  halves  of  the  cord.  The  posterior 
fissure  is  so  much  less  apparent  than  the  anterior,  that  some 
anatomists  deny  its  existence ;  but  by  careful  preparation  it  can 
be  demonstrated,  although  it  does  not  contain  a  fold  of  pia  mater. 
Indeed,  it  can  be  traced  to  a  greater  depth  than  the  anterior, 
and  reaches  down  as  far  as  the  posterior  grey  commissure  of 
the  cord. 

Besides  the  anterior  and  posterior  fissures,  along  each  half  of 
the  cord  are  two  superficial  grooves,  from  which  the  anterior  and 
posterior  roots  of  the  spinal  nerves  respectively  emerge.  These 

FIG.  157. 


1.  Dura  mater. 

2.  Arachnoid  mem- 

brane. 

3.  Ganglion  on   poste- 

rior root  of  spinal 
nerve. 


4.  Anterior     root      of 

spinal  nerve. 

5.  5.  Seat  of  sub-arach- 

noid fluid. 

6.  Posterior  branch  of 

spiual  nerve. 

7.  Anterior   branch  of 

spinal  nerve. 


COLUMNS. 


DIAGRAM    OF   A    THANSVERSE    SECTION    THROUGH    THE   SPINAL   CORD 
AND    ITS    MEMBRANES. 

are  the  anterior  and  posterior  lateral  fissures  (fig.  157). 
The  posterior  leads  down  to  the  posterior  horn  of  the  grey 
matter  in  the  interior  of  the  cord;  the  anterior  is  simply 
the  groove  from  which  the  anterior  roots  emerge.  By  these 
lateral  fissures  each  half  of  the  cord  is  divided  into 
three  longitudinal  columns — an  anterior,  a  pos- 
terior, and  a  lateral.  On  each  side  of  the  posterior  median 
fissure  is  a  slender  column,  called  the  posterior  median  column, 
which  is  separated  from  the  posterior  column  by  a  shallow  furrow. 
INTERNAL  A  transverse  section  through  the  cord  (fig.  157) 

STRUCTUBE.  shows  that,  externally,  it  is  composed   of  white 

nerve-substance,    and   that   its     interior    contains    grey    matter, 
arranged  in  the  form  of  two  crescents,  with  their  backs  to  each 


DISSECTION    OF    THE    SPINAL    CORD.  628 

other.  Each  crescent  is  placed  in  the  corresponding  half  of  the 
cord,  and  is  connected  with  its  fellow  across  the  centre  by  a 
portion  called  the  posterior  or  grey  commissure.*  The  posterior 
horns  are  long  and  narrow,  and  extend  to  the  posterior  lateral 
fissure,  where  they  are  connected  with  the  posterior  roots  of  the 
spinal  nerves.  The  anterior  horns  are  short  and  thick,  and  come 
forwards  towards  the  attachment  of  the  anterior  roots  of  the  nerves, 
but  do  not  reach  the  surface.  Separating  the  grey  commissure 
from  the  anterior  median  fissure  is  the  anterior  or  white  com- 
missure. 

On  making  transverse  sections  through  different  regions  of  the 
spinal  cord  the  grey  substance  is  seen  to  vary  in  shape :  in  the 
cervical  region  the  anterior  cornua  are  thick  and  short,  the  pos- 
terior are  long  and  slender ;  in  the  dorsal,  the  anterior  and 
posterior  cornua  are  both  thin ;  in  the  lumbar,  the  anterior  and 
posterior  cornua  are  large  and  broad ;  in  the  lower  part  of  the  cord 
the  grey  matter  is  arranged  in  a  central  mass.  Eunning  along  the 
CENTRAL  centre  of  the  cord  in  its  whole  length  is  a  minute 

CANAL,  canal,  just  visible  to  the  naked  eye.     It  is  lined 

with  cylindrical  ciliated  epithelium,  and  opens  superiorly  into  the 
fourth  ventricle.  The  central  canal  is  interesting,  as-  it  is  the 
remains  of  the  cavity  formed  by  the  spinal  cord  at  the  earliest 
period  of  its  development.-f- 

Thirty-one  pairs  of  nerves  arise  from  the  spinal 

SPINAL  NERVES.  .  ,          .    ,       .        .  .      , 

cord,  namely,  eight  in  the  cervical  region,  twelve 
in  the  dorsal,  five  in  the  lumbar,  five  in  the  sacral,  and  one  in  the 
coccygeal.     Each  nerve  is  formed  by  the  junction  of  two  series  of 
roots,  one  from  the  front,  the  other  from  the  back  of  the  cord. 
Two  BOOTS,  Sir  Charles  Bell  first  discovered  the  fact,  that 

SENSITIVE  AND  the  anterior  roots  consist  exclusively  of  motor 
MOTOR.  filaments,  and  the  posterior  exclusively  of  sensory. 

*  The  different  appearances  of  the  arrangement  of  the  grey  matter  in  the  cord 
have  been  accurately  described  and  figured  by  Rolando,  'Eicherche  Anatomiche  sulla 
Struttura  del  Midollo  Spinale,  con  Figure,  art.  tratto  dal  Dizionario  Periodico  di  Me- 
diana;'  Torino,  1824,  8vo.  p.  55. 

f  The  central  canal  is  well  seen  in  fishes,  birds,  and  reptiles. 


624  DISSECTION  or  THE  SPINAL  CORD. 

All  converge  in  the  corresponding  invertebral  foramen  to  form  a 
single  nerve,  composed  of  motor  and  sensory  filaments. 

The  filaments  of  the  posterior  or  sensory  roots  are  thicker  and 
more  numerous  than  the  anterior.  They  proceed  from  the  pos- 
terior lateral  fissure,  and  previous  to  their  union  with  the  anterior 
roots  are  collected  together  and  pass  through  a  ganglion. 
The  ganglion  is  of  an  oval  form,  and  lies  in  the  intervertebral 
foramen.  The  fibres  composing  these  roots  enter  the  cord,  and 
may  be  traced  to  the  posterior  cornu,  through  which  they  pass  in 
various  directions.  The  anterior  roots  arise  from  the  fissure 
between  the  anterior  and  lateral  columns  of  the  cord.  The  fibres 
of  the  anterior  root  may  be  traced  through  the  antero-lateral  fissure 
into  the  anterior  cornu.*  , 

The  compound  nerve  formed  by  the  junction  of  the  two  roots 
(after  the  formation  of  the  ganglion  of  the  posterior)  divides,  out- 
side the  intervertebral  foramen,  into  an  anterior  and  a  posterior 
branch.  See  diagram,  p.  622. 

VAHIATION  IN  The   direction  and  length  of  the  roots  of  the 

THE  LENGTH  OF  nerves  vary  in  the  different  regions  of  the  spine, 
THE  ROOTS.  owing  to  the  respective  parts  of  the  cord  from 

which  they  arise  not  being  opposite  to  the  foramina  through  which 
the  nerves  leave  the  spinal  canal.  In  the  upper  part  of  the  cer- 
vical region,  the  origins  of  the  nerves  and  their  point  of  exit  are 
nearly  on  the  same  level ;  therefore  the  roots  proceed  transversely, 
and  are  very  short.  Lower  down,  however,  the  obliquity  and 
length  of  the  roots  gradually  increase,  so  that  the  roots  of  the 
lower  dorsal  nerves  are  at  least  a  vertebra  higher  than  the  fora- 
mina through  which  they  emerge.  Again,  since  the  cord  itself 
terminates  at  the  upper  border  of  the  second  lumbar  vertebra, 

*  The  researches  of  Blandin,  'Anat.  descript.,'  t.  ii.,  p.  648,  1838,  have  led  him  to 
establish  the  following  relation  between  the  respective  size  of  the  anterior  and 
posterior  roots  of  the  nerves  in  the  several  regions  of  the  spine  : — 


The  posterior  roots  are  to  the  anterior  in  the  cervical  region 
,,  „  ,,  dorsal         „ 

lumbar  and  sacral 


1 


This  relation  quite  accords  with  the  greater  delicacy  of  the  sense  of  touch  in  the 
upper  extremity. 


DISSECTION    OF    THE    SPINAL    COED.  625 

the  lumbar  and  sacral  nerves  must  descend  from  it  almost  per- 
pendicularly through  the  lower  part  of  the  spinal  canal.  To 

CAUDA  this  bundle  of  nerves  the   old   anatomists   have 

EQUINA.  given  the  name  of  cauda  equina,  from  its  resem- 

blance to  a  horse's  tail. 

To  sum  up  briefly,  it  appears  that  the  spinal  cord  consists  of 
two  symmetrical  halves,  separated  in  front  and  behind  by  a  deep 
median  fissure ;  that  the  two  halves  are  connected  at  the  bottom 
of  the  anterior  fissure  by  an  anterior  or  white  commissure,  at  the 
bottom  of  the  posterior  fissure  by  the  posterior  or  grey  commissure  ; 
that  each  half  of  the  cord  is  divided  into  three  tracts  or  columns 
of  longitudinal  white  nerve-fibres — an  anterior,  a  lateral,  and  a 
posterior — the  boundaries  between  them  being  the  respective  lines 
of  origin  of  the  roots  of  the  spinal  nerves  ;  that  the  interior  of  the 
cord  contains  grey  matter  disposed  in  the  form  of  two  crescents, 
placed  with  their  convexities  towards  each  other,  and  connected 
by  a  transverse  bar  of  grey  matter,  which  constitutes  the  posterior 
commissure. 

BLOOD-VESSELS  The  cord  is  supplied  with  blood  by — 1.  The 
OF  THE  COED.  anterior  spinal  artery,  which  commences  at  the 
medulla  oblongata  by  a  branch  from  the  vertebral  of  each  side, 
and  then  runs  down  the  middle  of  the  front  of  the  cord.  Other 
branches  are  derived  from  the  vertebral,  ascending  cervical,  inter- 
costal, and  lumbar  arteries,  which  pass  through  the  intervertebral 
foramina,  and  assist  in  keeping  up  the  size  of  this  anterior  artery. 
2.  The  posterior  spinal  arteries,  which  proceed  also  from  the 
vertebral,  intercostal,  and  lumbar  arteries,  and  ramify  somewhat 
irregularly  on  the  back  of  the  cord. 

On  the  posterior  part  of  the  bodies  of  the  vertebrae,  the  spinal 
arteries  of  opposite  sides  communicate  by  numerous  transverse 
branches  along  the  entire  length  of  the  spine,  thus  resembling 
the  arrangement  of  its  venous  plexuses. 

FUNCTIONS  OF  The  spinal  cord  performs,  at  least,  three  func- 

THE  SPINAL  CORD,  tions: — 1.  It  is  the  general  conductor  of  impres- 
sions to,  and  from,  the  brain.  2.  It  transfers  impressions.  3,  It 
is  a  centre  of  reflex  action.  Sensory  impressions  are  conducted  by 

8  S 


626  DISSECTION   OF    THE    SPINAL    CORD. 

the  posterior  roots  of  the  spinal  nerves  to  the  cord,  and  are  thence 
transmitted  to  the  brain  through  the  posterior  columns  and  the 
grey  matter  of  the  cord.  These  impressions  do  not  run  up  on  the 
same  side,  for  the  fibres,  immediately  on  entering  the  grey  matter, 
cross  over  to  the  opposite  side  to  reach  the  brain  ;  so  that  if  the 
posterior  column  of  the  right  side  be  divided,  the  left  leg,  and  not 
the  right,  would  be  deprived  of  sensation.  Motor  impulses  are 
conveyed  along  the  antero-lateral  columns  and  the  grey  matter  in 
them,  and  carry  the  commands  of  the  will  from  the  brain  to  the 
muscles.  The  crossing  of  the  motor  fibres  takes  place  in  the 
medulla  oblongata,  at  the  decussation  of  the  anterior  pyramids,  so 
that  they  run  in  the  corresponding  half  of  the  cord  as  far  as  their 
point  of  decussation.  Division,  therefore,  of  one  half  of  the  cord 
below  this  point,  causes  paralysis  of  motion  on  the  same  side  of 
the  body.  .The:  cord  is,  .moreover,  concerned  in  the  conduction 
of  impressions  to  and  from  the  vaso-rtwtor  centre  of  the  medulla 
oblongata,  which  determines  the  varying  conditions  of  the  blood- 
vessels. The  cord  also  transfers  impressions ;  this  is  more  manifest 
in  disease  than  in  health ;  a  well-marked  example  of  transference  is, 
that  pain  is  felt  at  .the  -knee  in  cases  of  disease  of  the  hip-joint. 
The  spinal  cord  has  probably  no  power  of  originating  impressions, 
in  other  words,  it  is  not  automatic. 
MINUTE  STRUC-  These  are  among  the  most  complicated  parts  of 

TUBE  OF  THE  ME-  ^  central  nervous  system.  They  contain  white 
DCJI/LA  OBLONGATA  ,  .  ,  .  ,  mi  ,  ., 

T,  and    grey   nerve-matter   intermixed.     I  he   white 

AND  .TONS  &       J 

VAEOLH.  matter  consists,  in  part,  of  the  continuation  up- 

wards of  the  longitudinal  fibres  of  the  cord;  in  part,  of  horizontal 

fibres. 

ANTERIOR  The  anterior   columns   of  the   cord  (fig.  158), 

PYRAMIDS.  having  reached   the  lower  part  of  the   medulla 

oblongata,  are  not  continued  straight  through  it,  but  diverge 
from  each  other,  being  pushed  aside  by  the  deep  fibres  of  the 
lateral  columns,  which  here  cross  each  other,  and  form  the  de- 
cussation of  the  anterior  pyramids.  In  their  further  progress  the 
fibres  of  the  anterior  columns  are  arranged  thus  :  some  of  them  run 
up,  and  form  the  outer  portion  of  their  own  pyramid  :  some  ascend 


DISSECTION    OP    THE    SPINAL   COED. 


627 


beneath  the  olive  to  join  the  restiform  body;  a  third  set  pass 
upwards  and,  after  embracing  the  olive,  reunite,  to  form  a  single 
bundle ;  this,  joined  by  fibres  (olivary  fasciculus)  from  the  olive 
ascends  under  the  name  of  the  fillet  of  Reil,  over  the  superior  crus 
of  the  cerebellum  to  the  corpora  quadrigemina  and  the  cerebral 
hemispheres  (fig.  159). 

The  lateral  columns  on  reaching  the  medulla  oblongata  are 
disposed  off  in  three  ways,  as  follows : — some  of  its  fibres  come 
forward  between  the  diverging  anterior  columns,  decussate  in  the 
middle  line  and  form  part  of  the  pyramid  of  the  opposite  side ; 

Fio.  158. 


1.  Anterior  column. 

2.  Lateral  column. 

3.  Posterior  column. 

4.  Posterior  median  column 

of  the  spinal  cord. 

5.  Anterior  pyramid. 

6.  Eestiform  body. 


7.  Posterior  pyramid. 

8.  Fasciculus  teres. 

9.  Inferior  crus  of  the  cere- 

bellum. 

10.  To   the    corpora  quadri- 
gemina. 

11.  Crus  cerebri. 


DIAGRAM    OF   THE   COURSE    OF    THE    FIBRES    THROUGH    THE   MEDULLA   OBLONGATA. 

others  ascend  with  the  restiform  body  (or  tract)  into  the  cere- 
bellum ;  a  third  set  ascends  along  the  floor  of  the  fourth  ventricle 
(concealed  by  its  superficial  grey  matter)  as  the  fasciculus  teres, 
and  is  continued  along  the  upper  part  of  the  crus  cerebri  into 
the  cerebrum. 

RESTIFORM  The  posterior  columns  ascend  (under  the  name 

BODY,  of  the  restiform  bodies),  at  the  back  of  the  medulla, 

diverge  from  each  other,  and  are  continued  partly  into  the  cere- 
bellum, forming  its  inferior  crura,  and  partly  as  the  fasciculi 
teretes  along  the  floor  of  the  fourth  ventricle  into  the  cerebrum. 

s  s  2 


DISSECTION    OF   THE    SPINAL    COED. 

POSTEEIOK  These  are  the  continuations  upwards  of  the 

PYRAMIDS.  posterior  median  columns  of  the  cord ;  and,  like  the 

restifonn  body,  each  divides  into  two  fasciculi,  one  of  which  ascends 
and  helps  to  form  the  inferior  crus  of  the  cerebellum,  the  other 
runs  up  with  the  fasciculus  teres. 

HORIZONTAL  The  horizontal  fibres  in  the  medulla  oblongata 

FIBRES,  and  the  pons  were  first  accurately  described  by 

Stilling  and  subsequently  by  Kolando.  Some  of  them  form  a 
septum,  and  divide  the  medulla  oblongata  and  pons  into  sym- 
metrical halves  ;  others,  arising  apparently  from  the  septum,  pass 
outwards  in  an  arched  manner  through  the  lateral  halves  of  the 
medulla ;  so  that  when  seen  in  a  transverse  section  by  transmitted 
light,  they  describe  a  series  of  curves,  with  the  convexity  forwards, 
throughout  the  entire  thickness  of  the  medulla.  Some  of  these 
transverse  fibres  appear  on  the  surface  over  the  pyramid  and  the 
olive ;  these  have  received  the  name  of  arciform  fibres  of  Rolando 
(p.  584.)  Stilling  *  and  K611iker,f  who  have  studied  the  subject, 
are  of  opinion  that  they  originate  in  the  restiform  bodies,  and 
thence  arch  forwards — some  on  the  surface,  others  through  the 
substance  of  the  medulla,  and  that  they  eventually  join  the  fibres 
of  the  septum, 

INTERNAL  The  pons  consists  of  transverse  and  longitudinal 

STEUCTURE  OF  THE  white  fibres,  with  a  considerable  quantity  of  grey 
PONS  VAROLH.  matter  in  its  interior.  The  superficial  layer  of 
fibres  is  obviously  transverse,  and  connects  the  two  hemispheres  of 
the  cerebellum.  After  removing  the  first  layer,  we  expose  the 
longitudinal  fibres  of  the  pyramids  in  their  course  to  the  crura 
cerebri ;  these  longitudinal  fibres,  however,  are  intersected  by 
the  deep  transverse  fibres  of  the  pons,  which,  like  the  superficial, 
are  continued  into  the  cerebellum.  The  deepest  layer  of  the  pons 
consists  entirely  of  longitudinal  fibres,  derived  partly  from  the 
lateral  columns,  partly  from  the  restiform  bodies  of  the  medulla. 
CRURA  These  are  composed  of  longitudinal  fibres,  de- 

CEREBBI.  rived  from  the  pyramids,  from  part  of  the  lateral 

*  'Ueber  die  Medulla  Oblongata,'  Erlangen,  1843. 
f  'Mikroskopische  Anatomic,'  p.  454. 


DISSECTION   OP    THE    SPINAL    COED. 


629 


and  restiform  columns  of  the  cord,  and  from  the  grey  matter 
in  the  pons  Varolii.  If  one  of  the  crura  be  divided  longitudinally, 
there  is  found  in  the  middle  of  it  a  layer  of  dark-coloured  nerve- 
substance,  called  locus  niger,  which  separates  the  crus  into  an 
upper  and  lower  stratum  of  fibres.  The  lower  stratum  is  tough 
and  coarse,  and  consists  of  the  continuation  of  the  fibres  pro- 

FIG.  159. 


Corpus  striatum. 

Thalamus  opticus. 

Crus  cerebri. 

Locus  niger. 

Pons  Varolii,  denoted  by 

transverse  lines. 
Pyramid. 
Olive. 

Anterior  columns. 
Lateral  columns. 
Posterior  columns. 
Corpora  quadrigemina. 
Fillet  of  Eeil. 
Superior   crus  of     the 

cerebellum. 
Cerebellum. 


DIAGRAM    OF   THE    COURSE    OF   THE    FIBRES    THROUGH    THE   MEDULLA    AND    POKS. 

ceeding  from  the  pyramid  and  the  pons.  The  upper  stratum  is 
much  softer  and  finer  in  texture,  and  has  received  the  name  of 
tegmentum:  it  is  composed  of  the  fibres  proceeding  from  the 
lateral  and  restiform  columns ;  also  from  the  superior  crus  of 
the  cerebellum.  Tracing  the  fibres  of  the  crus  cerebri  into  the 


630  DISSECTION    OF   THE    SPINAL    CORD. 

cerebral  hemisphere,  we  find  that  its  lower  fibres  ascend  chiefly 
through  the  corpora  striata,  its  upper  fibres  through  the  thalami 
optici.  In  passing  through  these  ganglia,  the  crus  receives  a 
large  addition  to  its  fibres:  these  branch  out  widely  towards 
all  parts  of  the  hemisphere,  in  order  to  reach  the  cortical  sub- 
stance on  the  surface. 


631 


DISSECTION  OF  THE  EYE. 

SINCE  the  eye  in  the  human  subject  cannot  be  obtained  suf- 
ficiently fresh  for  anatomical  purposes,  the  student  should  examine 
the  eye  of  the  sheep,  bullock,  or  pig.  The  conjunctiva  membrana 
should  be  removed,  together  with  the  loose  connective  tissue  which 
unites  it  to  the  sclerotica. 

CONJUNCTIVA  ^e  conjunctiva  is  the  mucous  membrane  which 

covers  the  ocular  surface  of  the  eyelids  and  the 
anterior  part  of  the  globe,  and  is  lined  with  columnar  epithelium. 
It  is  loosely  attached  to  the  sclerotic  coat,  so  as  not  to  impede 
the  movements  of  the  globe.  The  palpebral  portion  of  it  is 
very  vascular,  and  provided  with  fine  papillae  abundantly  sup- 
plied with  nerves.*  It  is  continued  into  the  Meibomian  glands, 
the  puncta  lachrymalia,  and  the  ducts  of  the  lachrymal  gland. 
The  sclerotic  portion  is  thinner  and  has  no  papillae.  It  is  trans- 
parent and  nearly  colourless,  except  when  inflamed ;  it  then 
becomes  intensely  vascular,  and  of  a  bright"  'scarlet  colour.  An 
abundant  supply  of  nerves  is  distributed  to  the  membrane  ;  their 
arrangement  is  stated  to  be  the  same  as  that  of  the  skin,  but  many 
of  them  have  been  described  as  terminating  in  end-bulbs. 

The  corneal  conjunctiva  is  composed  chiefly  of  epithelium, 
arranged  in  layers.  This  portion  of  the  conjunctiva  cannot  be 
separated  by  dissection  in  recent  eyes,  but  it  possesses  the  same 
acute  sensibility  as  the  rest  of  the  conjunctiva.  Changes  produced 
by  inflammation  of  the  conjunctiva  often  involve  the  cornea 
and  render  its  texture  thick  and  opaque.f  Blood-vessels  ramify 

*  These  papillae  were  first  described  by  Eble, .,' Ueber  den  Bau  und  di&Krank- 
heiten  der  Bindehaut  des  Auges,' 

f  The  facts  of  comparative  anatomy  confirm  this  vievr.      In  the  serpent  tribe, 


632  DISSECTION    OF    THE    EYE. 

round  the  margin  of  the  cornea,  forming  a  network  arranged  in 
loops.  Lymphatics  exist  abundantly  in  the  palpebral  and  sclerotic 
conjunctiva,  and  communicate,  after  becoming  much  reduced  in 
size,  with  the  irregular  cell-spaces  of  the  cornea. 

The  human  eye  is  nearly  spherical,  the  antero-posterior  and 
vertical  diameters  being  equal,  the  transverse  exceeding  these  by 
less  than  half  a  line.  The  convexity  of  the  cornea  varies  in 
different  persons,  and  at  different  periods  of  life  ;  this  is  one  cause 
of  the  several  degrees  of  near  sight  and  far  sight. 

COATS  AND  He-  The  globe  is  composed  of  three  coats,  arranged 
MOUHS  OF  THE  one  within  the  other,  which  enclose  certain 
EYE-  transparent  structures.  The  external  coat,  con- 

sisting of  the  sclerotic  and  cornea,  is  fibrous,  thick,  and  strong. 
The  second  coat,  consisting  of  the  choroid,  the  iris,  and  the  ciliary 
processes,is  composed  of  blood- vessels,  muscular  tissue,  and  pigment- 
cell?,  and  is  very  dark  in  colour.  The  third  coat,  called  the  retina, 
consists  of  the  expansion  of  the  optic  nerve  for  the  reception  of  the 
impression  of  the  waves  of  light.  The  bulk  of  the  interior  is  filled 
with  a  transparent  humour,  called  the  vitreous  body.  Embedded 
in  the  front  of  this,  and  just  behind  the  pupil,  is  the  crystalline 
lens,  for  the  purpose  of  concentrating  the  rays  of  light.  In  front 
of  the  lens  is  placed  a  moveable  curtain,  called  the  iris,  to 
regulate  the  amount  of  .'light  .*which  shall  be  admitted  through  a 
central  aperture,  the  pupil,  to  the  fundus  of  the  eye.  The  space 
in  which  the  iris  is  suspended  is  filled  with  a  fluid,  termed  the 
aqueous  humour. 

SCLEEOTIC  The  sclerotic  is  the  tough  protecting  coat  of  the 

COAT.  eye,  and  consists  of  white  fibres  interlacing  in  all 

directions.*     It  covers  about  five-sixths  of  the  globe,  the  remaining 

which  annually  shed  the.  skin,  the  front  of  the  cornea  comes  off  with  the  rest  of  the 
external  surface  of  the  body.  In  the  eel  the  surface  of  the  cornea  is  often  drawn  off 
in  the  process  of  skinning.  In  some  species  of  rodents  which  burrow  under  the  ground 
like  the  mole,  the  eye  is  covered  with  hair, '.like  other  parts. 

*  The  sclerotic  coat  of  the  eye  in  fishes  is  of  extraordinary  thickness  and  density  ; 
and,  in  birds,  this  coat  is  further  strengthened  by  a  circle  of  bony  plates,  fourteen  or 
fifteen  in  number,  arranged  in  a  series  round  the  margin  of  the  cornea.  Similar 
plates  are  found  in  some  of  the  reptiles,  and  paiticularly  in  the  fossil  ichthyosauri 
and  plesiosauri. 


DISSECTION    OF    THE    EYE.  633 

one-sixth  being  completed  by  the  cornea.     The  thickest  part  of 

the  sclerotic  coat  is  at  the  back  of  the  globe  (fig.  161):;  the  thinnest 

is  a  short  distance  behind  the  cornea.*     The  back  of  the  sclerotic 

is  perforated  by  the  optic  nerve,  which  enters  it  about  one-tenth  of 

an  inch  on  the  nasal  side  of  the  axis  51G  160 

of  vision.     The   optic  nerve  at  its 

entrance  into  the  sclerotic  is  mudh 

constricted,  and  instead  of  passing 

through   a   single  aperture  in  this 

coat,   enters    it   through   a  porous 

network  of  fibrous  tissue,  called  the 

lamina  cribrosa.]     The  sheath   of 

the  optic  nerve  becomes  continuous 

with  the  sclerotic  where  it  perforates 

this  coat.     Around  the  optic  nerve 

the   sclerotic  is   perforated  by   the 

ciliary  arteries,  veins,   and   nerves, INSEETION  OF  THK  EECTI  MUSCT,ES  WITH 

~  ,,  -     ,,  ,  .  ,  ANTERIOR    CILIARY    ARTERIES. 

tor  the   supply  01  tne  choroid  and 

iris.  About  a  quarter  of  an  inch  from  the  cornea  the  sclerotic 
receives  the  insertion  of  the  recti  muscles ;  here  also  it  transmits 
the  anterior  ciliary  arteries,  which  run  forward  along  the  tendons 
of  these  muscles,  and  form  a  vascular  ring  around  the  margin  of 
the  cornea  (fig.  160). 

The  sclerotic  is  ^composed  of  connective  tissue  arranged  in 
bundles,  which  run,  some  longitudinally,  some  transversely.  The 
longitudinal  fibres  are  the  most  -external  and  abundant.  Under 
the  microscope  numerous  connective-tissue  corpuscles  may  be  seen 
filling  cell-spaces,  similar  to  those  found  in  the  cornea,  but  not  so 
abundant,  and  containing  pigment-granules.  Between  these  may 
be  demonstrated  fine  elastic  fibres.  The  inner  surface  of  the 
sclerotic  is  coated  with  a  thin  layer  of  connective  tissue,  lamina 
fusca,  in  which  are  found  some  pigment-cells. 

To  examine  the  cornea,  it  should  be  removed  with  the  sclerotic 

*  The  greatest  thickness  posteriorly  is  about  the  ^gth  °^  an  inch;  its  least  thick- 
ness in  front  is  about  ^th  of  an  inch. 

t  In  the  centre  of  the  lamina  cribrosa  is  an  opening  larger  than  the  rest,  which 
transmits  the  arteria  centralis  retinse. 


634 


DISSECTION    OF    THE    EYE. 


coat.  This  should  be  done  under  water,  by  making  a  circular  cut 
with  scissors,  about  a  quarter  of  an  inch  from  the  margin  of  the 
cornea.  With  a  little  care  it  will  be  easy  to  remove  the  outer  coat 
of  the  eye  without  injuring  the  dark  choroid  coat,  the  ciliary 
muscle,  or  the  iris.  In  the  loose  brown-coloured  connective  tissue 
between  the  sclerotic  and  the  choroid  are  the  ciliary  nerves  passing 
forwards  to  the  iris;  their  white  colour  makes  them  very  con- 
spicuous on  the  dark  ground. 

The  cornea  is  the  brilliant  translucent  coat  which 
forms  about  the  anterior  one-sixth  of  the  globe.    It 

FIG.  161. 


Hyaloid  membrane 


Retina  (dotted  line) 

Choroid  coat   (black 

line 

Sclerotic  coat    . 


Cornea. 

Iris. 

Ciliary  processes. 

Canal  of  Schlemm 

or  Fontana. 
Ciliary  ligament. 


1.  Anterior  chamber  filled  with  aqueous  humour. 

2.  Posterior  chamber.  3.  Canal  of  Petit. 

DIAGRAM    OF   A   VERTICAL    SECTION    OF   THE   EYE. 

is  nearly  circular  in  shape,  its  diameter  being  nearly  half  an  inch, 
and  its  thickness  about  -^  of  an  inch.  The  curve  of  the  cornea 
forms  part  of  a  smaller  circle  than  that  of  the  sclerotic,  so  that  it 
projects  further  forwards,  varying  in  this  respect  in  different  eyes, 
and  at  different  ages  of  life.  It  is  firmly  connected  at  its  margin 
to  the  sclerotic,  with  the  fibres  of  which  it  is  continuous.  The 
margin  of  the  sclerotic  is  bevelled  on  the  inside  ;  that  of  the  cornea 
on  the  outside,  so  that  the  former  overlaps  the  latter  (fig.  161). 


DISSECTION    OP    THE    EYE.  635 

The  cornea  consists  of  five  layers,  which  are  not 
all  composed  of  the  same  kind  of  tissue.  The 
most  superficial  layer  is  the  conjunctival.  This  consists  of  several 
strata  of  epithelial  cells ;  the  deeper  ones,  the  more  numerous,  are 
columnar  and  placed  vertically,  the  superficial  ones  are  flattened 
scaly  epithelium  cells,  with  well-marked  nuclei.  The  second 
layer  is  about  the  TSTRT  of  an  inch  thick,  and  consists  of  a  perfectly 
structureless  lamina,  which,  when  peeled  off,  has  a  remarkable 
tendency  to  curl.  Boiling,  or  the  action  of  acids,  does  not  render 
it  opaque,  like  the  other  layers  of  the  cornea.  The  third  layer 
(cornea  proper}  consists  of  translucent,  connective  tissue,  upon 
which  the  thickness  and  strength  of  the  cornea  mainly  depend. 
The  fibres  are  arranged  in  layers,  about  sixty  in  number.  Between 
the  laminae  are  irregularly  branched  spaces,  called  the  cell-spaces  of 
the  cornea.  In  these  spaces  are  lodged  the  corneal  corpuscles, 
with  outstanding  processes,  which  communicate  freely  with  each 
other,  and  correspond  in  shape  to  the  spaces  within  which  they  lie. 
In  inflammation  of  the  cornea  these  corpuscles  undergo  consider- 
able changes.*  The  fourth  layer  is  translucent,  elastic  and 
brittle,  and  may  be  easily  separated  from  the  preceding  laminse. 
Like  the  second  layer,  it  is  unaffected  by  boiling  or  by  the  action 
of  acids  or  alkalies,  but  is  somewhat  thinner,  being  from  20'00  to 
-3  Vo~  of  an  inch  in  thickness.  It  is  termed  the  membrane 
of  Descemet.  In  the  sclerotic  coat,  close  to  its  junction  with  the 
cornea,  is-situated-'a  smalb  aval  canal,  lined  with  epithelium, 
termed  the  sinus  circularis  iridis,  or  canal  of  Schlemm  (fig. 
161).  It  is  probably  a  venous  sinus,  for  it  can  always  be 
injected  from  the  arteries.  The  Jifth  layer  consists  of  a  single 
layer  of  polygonal  epithelial  cells-,  resembling  those  which  line 
serous  membranes.f  In  its  healthy  state  the  cornea  contains  no 

*  If  fluid  be  injected  very  gently  into  the  cornea  proper,  there  may  be  demon- 
strated a  system  of  canals,  called  Kecklinghausen 's  canals,  which  are  the  communica- 
tions between  the  corneal  corpuscles ;  but  if  the  fluid  be  injected  more  forcibly,  it 
passes  in  the  course  of  the  fibres  composing  the  various  laminae  of  the  cornea,  which 
gives  the  appearance  of  a  number  of  varicose  and  enlarged  tubes  crossing  each  other 
at  right  angles:  these  are  termed  Bowman's  corneal  tubes. 

f  For  a  detailed  description  of  the  structure  see  Todd  and  Bowman, 'Physio- 
logical Anatomy.' 


636  DISSECTION   OP   THE    EYE. 

blood-vessels,  except  at  its  circumference,  where  they  form  loops. 
Its  nerves,  which  are  numerous,  forty  to  forty-five  in  number,  may 
be  traced  forwards  in  the  transparent  tissue  as  a  fine  plexus ;  this 
gives  off  minute  fasciculi,  which  ramify  beneath  the  epithelium, 
constituting  the  sub-epithelial  plexus.  From  this  very  minute 
filaments  run  between  the  epithelium  cells,  forming  the  intra- 
epithelial  plexus. 

After  the  removal  of  the  sclerotic  and  cornea, 
we  expose  the   choroid  coat,*  and  its  continuation 
formerly  known  as  the  ciliary  processes.     In  connection  also  with 
this  tunic  is  a  white  ring,  the  ciliary  muscle. 

The  choroid  is  the  soft  and  flocculent  tunic  of  the  eye,  recog- 
nised by  its  dark  brown  colour  and  great  vascularity.  Posteriorly 
there  is  a  circular  aperture  in  it  for  the  passage  of  the  optic  nerve. 
In  front,  the  choroid  passes  beneath  the  ciliary  muscle  with 
which  it  is  connected,  and  then  extends  forwards,  terminating 
in  a  series  of  plaited  folds,  called  the  ciliary  processes.  It  is 
connected  with  the  sclerotic  by  delicate  connective  tissue,  the 
lamina  fusca,  through  which  the  ciliary  vessels  and  nerves  pass 
forwards. 

CILIARY  PRO-  The  ciliary  processes  are  the  folds  formed  by 

CESSES.  the  anterior  part  of  the  choroid,  and  may  be  best 

seen  when  the  globe  has  been  divided  by  a  vertical  section  into  an 
anterior  and  a  posterior  half,  the  ^vitreous  humour  being  left  un- 
disturbed. They  are  black,  and  »consist  of  from  sixty  to  seventy 
radiating  folds,  arranged  in  a  circle  about  three  lines  broad.  These 
processes  consist  of  longer  and  shorter  folds,  the  former  being  the 
more  numerous.  The  longer  fold  is  about  a  line  in  length ;  the 
smaller  about  half  a  line.  One  of  the  longer  ones  is  seen  in 
the  diagram,  p.  634.  The  processes  fit  into  corresponding  folds 
of  the  suspensory  ligament  of  the  lens,  and  their  free  ends 
project  for  a  short  distance  into  the  posterior  chamber.  The 
vascular  supply  of  the  ciliary  processes  is  most  abundant,  and 
resembles  in  the  main  that  of  the  choroid.  The  ^arteries  come 

*  So  called  because  its  outer  flocculent  surface  somewhat  resembles  the  choriou, 
or  external  investment  of  the  ovum. 


DISSECTION    OF    THE    EYE.  .637 

chiefly  from  the  anterior  ciliary,  and  from  the  front  vessels  of  the 
choroid ;  and  after  breaking  up  into  a  fine  plexus,  they  form  loops 
which  arch  backwards  to  end  in  the  smaller  veins.  Their  dark 
colour  arises  from  pigmented  cells,  which  disappear,  however,  at 
the  free  ends  of  the  processes. 

Under  the  microscope  the  choroid  is  seen  to  consist  of  two  layers, 
both  composed  of  blood-vessels  held  together  by  fine  connective 
tissue,  in  which  are  found  large  ramified  pigment-cells.  The  outer 
layer  consists  of  the  larger  branches  of  the  blood-vessels ;  the 

Fm.  162. 

^t 

Sclerotic  coat    .    . 

Veins  of  the  choroid. — JffiSI  BS^ Ciliary  body. 


___ —   Iris. 

Ciliary  nerves  . 


Veins  of  the  choroid . 


SCLEROTIC    COAT    BEHOVED    TO    SHOW   THE    CHOEOID,    CILIARY   LIGAMENT,    AND    NERVES. 

arteries  (short  ciliary)  being  chiefly  on  the  inner,  the  veins  on  the 
outer,  surface.  The  veins  are  arranged  with,  great  regularity  in 
drooping  branches  (vasa  vorticosa\.  like  a  weeping-willow  (fig. 
162),  and  converge  to  four  or  five  nearly  equidistant  trunks,  which, 
after  running  backwards  for  a  short  distance,  perforate  the  sclerotic 
not  far  from  the  entrance  of  the  optic  nerve,  and  empty  themselves 
into  the  ophthalmic  vein.  The  inner  layer  is  formed  by  the 
capillaries  of  the  ciliary  arteries,  and  is  called,  after  the  Dutch 
anatomist  Ruysch,  '  tunica  Ruysckiana?  It  consists  of  the  most 
delicate  vascular  network  found  in  any  tissueyand  extends  forwards 
to  the  ciliary  processes,  with  the  capillaries  of  which  it  freely 
communicates. 


638  DISSECTION    OP   THE    EYE. 

Between  the  choroid  membrane  and  the  lamina  fusca  of  the 
sclerotic  is  a  layer  of  connective  tissue,  the  lamina  supra  cho- 
roidea,  which  serves  to  connect  the  two  tunics. 

CILIARY  This   muscle   consists    of  unstriped  fibres,  and 

MUSCLE.  arises  by  a  thin  tendon  from  the  sclerotic  close  to 

its  junction  with  the  cornea.  Thence  its  fibres  radiate  backwards, 
and  are  lost  in  the  choroid  behind  the  ciliary  processes.  Some 
of  these  fibres  form  a  circular  muscle  around  the  outer  circum- 
ference of  the  iris,  constituting  the  circular -ciliary  muscle,  which 
was  formerly  described  as  the  ciliary  ligament.  Its  action  is  to 
accommodate  the  eye  to  objects  at  various  distances,  by  rendering 
the  lens  more  or  less  convex.* 

The  iris  is  the  contractile  curtain  suspended  in 
the  clear  fluid,  which  fills  the  space  between  the 
cornea  and  the  lens.  The  iris  divides  this  space  into  two  un- 
equal parts,  called  the  anterior  and  posterior  chambers  (fig.  161); 
these  communicate  -with  each  other  through  a  circular  aperture  in 
the  centre,  called  the  pupil.^  Its  use  is  to  regulate  the  amount 
of  light  which  shall  be  admitted  into  the  eye :  for  this  purpose  its 
inner  circumference  is  capable  of  dilating  and  contracting  accord- 
ing to  circumstances,  while  its  outer  circumference  is  immoveably 
connected  with  the  ciliary  muscle,  the  choroid  and  the  cornea.  % 

The  colour  of  the  iris  varies  in  different  individuals,  and  gives 
the  peculiar  tint  and  brilliancy  to  the  eye.  The  colouring  matter 
or  pigment  is  contained  in  minute  cells  (pigment  cells),  lining  the 
anterior  and  posterior  surfaces  of  the  iris,  the  posterior  taking  the 
name  of  uvea  from  its  grape-like  colour.  Pigmented  cells  are 
also  found  in  the  substance  of  the  iris. 

When  the  iris  is  laid  under  water,  and  viewed  with  a  low  mag- 
nifying power,  it  is  seen  to  be  composed  of  fine  fibres  converging 
from  all  sides  towards  the  pupil ;  many  of  them  unite  and  form 

*  Sir  Philip  Crampton  has  noticed  that  this  muscle  is  well  developed  in  birds. 
In  them  its  fibres  are  of  the  striped  variety,  just  as  the  circular  fibres  of  the  iris  are. 

•f  The  size  and  shape  of  the  pupil  vary  in  different  animals.  In  the  bullock, 
sheep,  horse,  etc.,  it  is  oblong  ;  in  carnivorous  quadrupeds  it  is  often  a  mere  vertical 
slit  during  the  day,  but  dilates  into  a  large  circle  at  night. 

J  The  diameter  of  the  pupil  in  man  varies  from  the  ^th  to  the  |  of  an  inch. 


DISSECTION    OP    THE    EYE.  639 

arches,   leaving   elongated   interspaces,  which   are  most   marked 
towards  the  middle  of  the  iris. 

The  contractile  power  of  the  iris  depends  upon  muscular  fibres 
of  the  non-striped  kind,  arranged  some  in  a  radiating,  others  in  a 
circular  manner.  The  radiating  (dilatator  iridis}  converge 
towards  the  pupil,  where  they  form  arches  and  blend  with  the 
circular  fibres  ;  the  .circular  ($phincter\  well  marked,  are  collected 
on  the  posterior  aspect  of  the  pupillary  margin,  where  they  form 
a  ring  about  ^th  of  an  inch  in  width.* 

A  considerable  amount  of  connective  tissue  is  present  in  the 
iris,  forming  the  stroma,  and  consists  of  circular  and  radiating 
fibres;  the  circular  are  found  at  the  circumference  of  the  iris,  the 
radiating  converge  towards  the  pupil.  In  front  of  the  iris  is  a 
thin  layer  of  epithelium,  .which  is  continuous  with  that  covering 
the  membrane  of  Descemet. 

When  minutely  injected,  the  iris  appears  to  be  composed  almost 
entirely  of  blood-vessels ;  they  form,  in  the  ciliary  muscle  at  the 
outer  circumference  of  the  iris,  a  vascular  circle  (the  circulus 
'major},  from  which  numerous  small  branches  pass  inwards,  and 
form  another  circle  (circulus  minor\  which  terminates  -in  the 
veins  of  the  iris. 

Its  blood-vessels  are  derived  from  two  sources — the  posterior 
or  long,  and  the  anterior  ciliary  arteries.  The  long  ciliary  arteries, 
two  in  number,  perforate  the  sclerotica  on  <  each  side  of  the  optic 
nerve,  and  then  run  forwards  upon  the  choroid  to  the  ciliary  muscle  ; 
here  they  divide  into  branches  constituting  the  circulus  major, 
just  described :  the  anterior,  five  or  six  -in  number,  are  derived 
from  the  muscular  branches,  and  ramify  on  the  tendons  of  the  recti 
muscles  (p.  212),  where  they  perforate  the  sclerotica  behind  the 
margin  of  the  cornea.  These  vessels  supply -the  ciliary  processes 
and  iris,  and  it  is  from  their  enlargement  that  the  red  zone  round 
the  cornea  is  produced  in  inflammation  of  the  iris. 

CILIARY  The  nerves  of  the  iris,  about  fifteen  in  number, 

NERVES.  proceed   from  the  lenticular  ganglion,  and  from 

*  The  circular  fibres  of  the  iris  in  the  bird  are  of  the  striped  variety,  and  discern- 
ible without  difficulty. 


640  DISSECTION    OF    THE    EYE. 

the  nasal  branch  of  the  ophthalmic  division  of  the  fifth  nerve 
(p.  213).  They  perforate  the  back  of  the  sclerotica  like  the 
arteries,  run  along  the  choroid  which  they  supply  in  their  course, 
and  then  break  up  into  a  fine  non-medullated  plexus,  which 
supplies  the  ciliary  muscle  and  iris. 

MEMBBANA  Until  the  seventh    or  eighth   month  of  foetal 

PUPILLABIS.  life,  the  pupil  is  closed  by  a  delicate  membrane, 

the  membrana  pupillaris.  Its  vessels,  derived  from  those  of 
the  iris  and  capsule  of  the  lens,  are  arranged  in  loops  which 
converge  toward  the  centre  of  the  membrane.  Quekett  has 
described  this  membrane,  which  has  always  been  regarded  as 
a  distinct  structure,  as  identical, with  the  anterior  layer  of  the 
capsule  of  the  lens.* 

To  obtain  a  view  of  the  retina,  the  choroid 
coat  must  be  carefully  removed  while  the  eye  is 
under  water ;  this  should  be  done  with  the  forceps  and  scissors 
on  a  fresh  eye.  The  optic  nerve,  having  entered  the  interior  of  the 
globe  through  the  sclerotic  and  the  choroid,  expands  into  the  deli- 
cate nervous  tunic  called  the  retina.  In-  passing  through  the 
coats  of  the  eye  the  nerve  becomes  gradually  constricted  and 
reduced  to  one-half  of  its  diameter  ;•- here  it  presents  a  round 
disk,  called  the  porus  -opticus,  in  the  centre  of  which  may  be  seen 
the  arteria  centralis  retina3.  At  this  point,  too,  the  nerve-sub- 
stance projects  slightly  into  the  interior  of  the  globe,  forming  a 
little  prominence,  to  which  the  term  colliculus  nervi  optici  has  been 
applied.-J-  In  front  the  retina  terminates  a  little  behind  the  poste- 
rior margin  of  the  ciliary  processes  in  a  thin  serrated  border  (ora 
serrata). 

Precisely  opposite  the  pupil,  in  the  centre  of  the^  axis  of 
vision,  there  is  an  oval  yellow  spot,  maeula  lutea,  in  the  retina, 
about  gVth  of  an  inch  in  diameter,  fading  off  gradually  at  the 
edges,  and  having  a  black  spot,  .fovea  centralis,  in  the  centre. 

*  See  a  paper  by  John  Quekett  in  the  'Transactions  of  the  Microscopical  Society 
of  London,'  vol.'.iii.  p.  .9. 

ft  This- prominence  is- remarkable  in  that  it -is  insensible  to  the  rays  of  light.  It  is 
termed  the  '  blind  spot.' 


DISSECTION   OP   THE    EYE. 


641 


Here  vision  is  the  most  perfect ;  so  then  it  might  be  called  the 
"spot  of  sight."  This  central  spot  was  believed  by  its  discoverer, 
Sommering,  to  be  a  perforation ;  but  it  is  now  ascertained  to  be 
due  to  the  pigmentary  layer  of  the  retina  showing  through  it. 
These  appearances  are  lost  soon  after  death,  and  are  replaced  by  a 


FIG.  163. 


8.  Layer  of  pigment  cells. 


7.  Layer  of  rods  and  cones. 
(Membrana  Jacobi.) 


Membrana  limitans  ext. 


6.  Outer  nuclear  layer. 


5.  Outer  molecular  layer.  5 


4.  Inner  nuclear  layer. 


3.  Inner  molecular  layer. 


2.  Layer  of  nerve-cells. 
1.  Layer  of  nerve-fibres. 

Membrana  limitans  interna. 

DIAGRAM   OF   THE   VARIOUS    LAYERS    OF   THE    RETINA.       (After  Quain.) 

minute  fold,  into  which  the  retina  gathers  itself,  reaching  from 
the  centre  of  the  spot  to  the  prominence  of  the  optic  nerve.* 

*  In  birds  the  retina  has  throughout  the  yellowish  colour  seen  only  at  one  part  in 
the  human  eye. 

T  T 


642  DISSECTION   OP   THE    EYE. 

MIOTTE  STEUC-         Although  to  the  naked  eye  the  retina  appears 
TUBE  OF  THE  a   simple,  soft,  semi-transparent  membrane,  yet, 

KETINA.  when  examined  under  the  microscope,  it  is  found 

to  be  most  minutely  and  elaborately  organised.  It  varies  in 
thickness  from  the  -yV  to  the  ^tr  of  an  inch,  being  thickest  behind 
and  gradually  diminishing  towards  the  front.  It  consists  of  eight 
layers,  through  which  may  be  traced  a  considerable  amount  of 
extremely  delicate  connective  tissue  (fibres  of  Miiller),  which 
constitutes  a  scaffolding  for  the  various  strata,  and  is  said  to  form 
for  them  two  more  or  less  continuous  boundary  lines  termed 
membrance  limitantes,  internet,  and  externa.  The  layers  are  as 
follows,  beginning  from  within  : — 

1 .  The  layer  of  nerve-fibres  is  composed  of  the  spreading  out 
of  the  optic  nerve-fibres  and  of  connective-tissue  cells.     The  nerve- 
fibres,  consisting  only  of  the  axis-cylinders,  run  forwards  as  a  con- 
tinuous layer,  and,  in  fact,  become  connected  with  the  nerve-cells 
of  the  next  layer.     The  fibres  are  absent  on  the  yellow  spot. 

2.  The   ganglionic   layer   is   a   single  stratum  of  spheroidal 
nerve-cells  :  from  the  deeper  part  of  each  cell  there  is  given  off 
an  elongated  process,  which  passes  obliquely  into  the  nerve-fibre 
layer,  with  which  it  becomes  incorporated  ;  from  the  opposite  side 
of  the  cell  two  or  more  processes  pass  outwards  and  become  lost  in 
layer  No.  3.    The  ganglionic  cells  which,  in  the  greater  extent  form 
a  single  layer,  are  at  the  yellow  spot  arranged  eight  or  ten  deep. 

3.  The  inner  molecular  layer  is  a  granular  stratum  of  con- 
siderable thickness,  with  a  structureless  matrix.     In  it  are  found, 
also,  the  processes  of  the  cells  of  the  preceding  layer,   and  some 
varicose  filaments  which  pass  inwards  from  the  next  stratum. 

4.  The  inner  nuclear  layer  is  said  to  contain  three  or  four 
kinds  of  cells,  some  of  which  belong  to  the  Mullerian  or  connect- 
ing tissue  fibres  of  the  retina ;  others,  the  more  numerous,  are 
bipolar  nerve-cells.     It  is  hard  to  give  an  intelligible  description 
of  this  layer,  so  long  as  even  experts  make  such  different  state- 
ments concerning  it. 

5.  The  outer  molecular  or  internuclear  layer  resembles  in 
most  respects  the  inner  molecular  layer,  but  is  much  thinner. 


DISSECTION    OP    THE    EYE.  643 

6.  The  outer  nuclear  layer  consists  of  a  considerable  thickness 
of  nucleated  cells,  with  an  outward  and  an  inward  filament,  which 
may  be  recognised  as  connected  respectively  with   the  rods  and 
cones  of  the  next  layer.     The  rod-granules  are  the  most  numerous, 
and  each  has  an  enlargement  which  presents  a  well-marked  trans- 
verse  striation ;    from    this    enlargement    one   varicose    filament 
passes  inwards  and  becomes  connected  with  the  outer  molecular 
layer ;    the    other   becomes   continuous   with  a  rod.     The    cone- 
granules  are  fewer  and  thicker,  and,  like  the  rod-granules,  one  end 
terminates  in  the  outer  molecular  layer,  the  other  passes  into  the 
base  of  a  cone. 

7.  The  rods  and  cones,  bacillary  layer,  or  Jacob's  membrane, 
is    composed    of  minute  cylindrical  elements   arranged  at   right 
angles  to  the  surface  of  the  retina.     The    rods,  the  more  nume- 
rous, are  tapering  processes  running  through  the  whole  thickness 
of  this  layer,  and  externally  are  embedded  to  a  greater  or  less 
depth  in  the  pigmental  layer,  so  that  when  viewed  from  without 
they  have  the  appearance  of  mosaic  pavement.     Among  the  rods 
are   intermingled   numerous    shorter    flask-shaped    bodies,    called 
cones  ;  their  outer  extremities  taper  off  towards  the  choroid,  their 
inner  broad  ends  are  connected  with  the  fibres  of  Mu'ller  and  the 
outer  nuclear  layer.     The  rods  are  absent  at  the  yellow  spot. 

8.  The  pigmentary  layer  is  usually  described  as  forming  part 
of  the  choroid  coat,  but  it   should  be  included  more  properly  as 
one  of  the  layers  of  the  retina.     It  consists  of  a  single  layer  of 
hexagonal  nucleated  cells  filled  with  pigment-granules,  which  are 
most  numerous  towards  the  margins  of  the  cells.     The  use  of  the 
pigment  is  to  absorb   the  rays  of  light  which  pass  through  the 
retina,  and  thus  prevent  their  being  reflected.     It  serves  the  same 
purpose  as  the  black  paint  with  which  the  inside  of  optical  instru- 
ments is  darkened.     Albinoes,  in  whom  this  layer  has  little  or  no 
pigment,  are,  consequently,  dazzled  by  daylight  and  see  better  in 
the  dusk.* 

*  In  many  of  the  nocturnal  carnivorous  quadrupeds,  the  inner  surface  of  the 
choroid  at  the  bottom  of  the  eye  presents  a  brilliant  colour  and  metallic  lustre.  It 
is  called  the  tapetum.  By  reflecting  the  rays  of  light  a  second  time  through  the 

T  T  2 


644  DISSECTION   OF    THE    EYE. 

The  arteria  centralis  retince,  after  emerging  through  the 
porus  opticus,  divides  into  two  branches — an  upper  and  a  lower — 
which  then  form  a  delicate  network  of  blood-vessels  throughout 
the  nerve-fibre  layer,  penetrating  as  far  as  the  inner  nuclear  layer, 
beyond  which  no  capillaries  can  be  traced.  After  maceration  in 
water,  the  nervous  substance  can  be  removed  with  a  camel's 
hair  brush,  and  then  in  an  injected  eye  the  network  formed  by  the 
vessels  can  be  distinctly  seen.  The  arteries  of  the  retina  do  not 
communicate  directly  with  the  choroidal  vessels. 

c,  The  various  layers  of  the  retina  are  thinner  at 

STRUCTURE  OF  J 

THE  MACULA  the  fovea,  except  the  cones,  which  are  much  elon- 

LUTEA  AND  FOVEA  gated.  It  is  destitute  of  rods  and  of  the  nerve- 
CENTRALIS.  f^Ye  iaver€  At  the  margin  of  the  fovea  most  of 

the  layers  are  thicker  than  elsewhere. 

AQUEOUS  The  aqueous  humour  consists  of  a  few  drops  of 

HUMOUR.  an  alkaline  clear  watery  fluid,  which  fills  the  space 

between  the  cornea  and  the  lens.*  The  iris  lies  in  it,  and  divides 
the  space  into  two  chambers  of  unequal  size — an  anterior  and  a 
posterior.  The  posterior  is  much  the  smaller  of  the  two  ;  indeed, 
the  iris  rests  on  the  capsule  of  the  lens,  so  that,  strictly  speaking, 
there  is  no  interval  between  the  opposed  surfaces,  hence  no  such 
space  really  exists.  This  accounts  for  the  frequent  adhesions  which 
take  place  during  inflammation  of  the  iris,  between  the  iris  and 
the  capsule  of  the  crystalline  lens.f  A  delicate  layer  of  epithelium 
covers  the  posterior  surface  of  the  cornea,  but  nothing  like  a  con- 
tinuous membrane  can  be  demonstrated  on  the  iris  or  the  capsule 
of  the  lens.  The  anterior  chamber  is  remarkable  for  the  rapidity 
with  which  it  absorbs  and  secretes,  as  is  proved,  in  the  one  case, 
by  the  speedy  removal  of  extravasated  blood ;  in  the  other,  by  the 
rapid  reappearance  of  the  aqueous  humour  after  the  extraction  of 
a  cataract. 

retina,  it  probably  enables  the  animal  to  see  better  in  the  dusk,  It  is  the  cause  of 
the  well-known  glare  of  the  eyes  of  cats  and  other  animals  ;  and  the  great  breadth 
of  the  luminous  appearance  arises  from  the  dilatation  of  the  pupil. 

*  The  solid  constituent  is  mainly  composed  of  chloride  of  sodium. 

f  Some  anatomists  describe  the  anterior  chamber  as  lined  by  a  serous  membrane 
called  the  membrane  of  the  aqueous  humour. 


DISSECTION    OF    THE    EYE.  645 


THE  VITBEOUS  ^e  vitreous  body  ig  a  transparent,  gelatinous- 
BODT  AND  THE  looking  substance,  which  fills  up  nearly  four-fifths 
HYALOID  MEH-  of  the  interior  of  the  globe  (p.  634).  It  can  be 
easily  separated  from  the  retina,  except  at  the 
optic  disc;  in  front  it  presents  a  deep  depression,  in  which 
the  crystalline  lens  is  embedded.  It  is  surrounded  by  a  delicate 
transparent  membrane,  the  hyaloid  membrane,  which  forms  a 
capsule  for  the  vitreous  body,  and  is  sufficiently  strong  to  keep  it 
in  shape  after  the  stronger  tunics  of  the  eye  have  been  removed. 

When  the  vitreous  humour  has  been  hardened  in  chromic 
acid  it  is  rendered  somewhat  opaque,  and  presents,  especially  at 
its  outer  part,  a  lamellar  appearance.  It  consists  of  a  fluid  con- 
tained in  the  meshes  of  a  cellular  structure,  which  communicate 
freely  with  each  other  ;  for  if  any  part  of  it  be  punctured,  the 
humour  gradually  drains  away.*  If  examined  carefully,  the 
lamellation  is  seen  to  be  arranged  concentrically,  the  layers,  as 
they  approach  the  centre,  becoming  less  firm  in  consistence.  The 
vitreous,  moreover,  on  a  transverse  section  shows  a  radial  striation, 
but  whether  this  exists  naturally,  or  is  the  result  of  post-mortem 
changes,  or  from  chemical  reagents,  is  not  known.  Running 
through  the  middle  from  before  backwards  is  a  small  canal  — 
canal  of  Stilling  —  about  a  line  in  diameter, 
which  contains  fluid,  and  is  broader  behind 
than  in  front;  this  in  the  foetus  lodges  a 
small  branch  of  the  retinal  artery,  which 
ramifies  on  the  back  of  the  capsule  of  the  lens. 

Surrounding   the    hollow 
ZONE  OF  ZINN.       .  . 

in   the  vitreous  which    re- 

ceives the   crystalline  lens  is   the  zone   of 

Zinn.\  This  zone  is  best  exposed  by  remov-  AETE*IES  OF  THE  RETINA' 

ing  the  ciliary  processes.     It  appears  as  a  canai  of  Petit  (inflated). 

11  T    ,-  i-  i  if  J.T-       Zone  of  Zinn  (exaggerated). 

dark,  radiating  disk,  and  extends  from  the 

front   margin   of  the  retina  nearly  to  the  capsule  of  the  lens  ; 

*  This  is  composed  mainly  of  water,  with  albuminate  of  soda,  and  muciii. 
f  Zinn  was  Professor  of  Anatomy  at  Gb'ttingen  about  the  middle  of  the  eighteenth 
century,  and  author  of  '  Descriptio  Anat.  Oculi  Humani.' 


DISSECTION    OF    THE    EYE. 

its  surface  is  marked  by  prominent  ridges,  which  correspond  with 
the  intervals  between  the  ciliary  processes  (fig.  164).  It  assists 
in  maintaining  the  lens  in  its  proper  position,  and  is  firmly 
connected  with  its  capsule. 

CANAL  OF  If  the  transparent  membrane  between  the  zone 

PETIT,  of  Zinn  and  the  margin  of  the  lens  be  carefully 

punctured,  and  the  point  of  a  small  blow-pipe  gently  introduced, 
and  air  or  fluid  injected,  we  may  succeed  in  inflating  a  canal  which 
encircles  the  lens  :  this  is  the  canal  of  Petit,  or  '  canal  godronne ' 
(fig.  164).  This  canal  is  usually  described  as  formed  by  the 
separation  of  the  hyaloid  membrane  into  two  layers ;  the  anterior 
— the  zone  of  Zinn — being  continued  forwards  in  front  of  the  lens, 
the  posterior  passing  behind  it. 

CRYSTALLINE  The   crystalline  lens  (fig.  161)   is   a   perfectly 

LENS-  translucent  solid  body,  situated  immediately  be- 

hind the  pupil,  and  partly  embedded  in  the  vitreous  body.  It  is 
convex  on  both  sides,  but  more  so  behind.  In  early  life  it  is 
nearly  spherical  and  soft,  but  it  becomes  more  flattened,  firmer,  and 
amber-coloured  with  advancing  age.  In  the  adult  its  transverse 
diameter  is  about  one-third  of  an  inch ;  its  antero-posterior,  one- 
fifth  of  an  inch. 

The  lens  is  surrounded  by  a  capsule  equally  translucent  as 
itself.  The  capsule  is  brittle,  and  is  composed  of  a  structure 
similar  to  the  elastic  layer  of  the  cornea.  It  is  four  times  thicker 
in  front  than  behind,  as  might  be  expected,  for  the  sake  of  more 
effective  support.  No  vascular  connection  whatever  exists  between 
the  lens  and  its  capsule.*  The  lens  protrudes  directly  the  capsule 
is  sufficiently  opened. 

MINUTE  STKUO         The  minute  structure  of  the  lens  can  only  be 

TUBE  OF  THE  made  out  after  being  hardened.     It  is  soft,  almost 

gelatinous  in  consistence  outside,  but  each  suc- 

*  The  vessel  of  the  capsule  of  the  lens  is  derived  from  the  arteria  centralis  retinae, 
and  in  mammalia  can  only  be  injected  in  the  foetal  state.  In  the  reptilia,  however, 
the  posterior  layer  of  the  capsule  is  permanently  vascular.  This  small  artery  passes 
forwards  through  the  canal  of  Stilling  to  the  posterior  part  of  the  capsule  of  the 
lens,  on  which  it  radiates  into  numerous  small  branches,  communicating  with  branches 
in  the  iris  and  pupillary  membrane. 


DISSECTION   OF   THE    EYE.  647 

cessive  layer  becomes  more  dense,  so  that  the  central  part  is  hard, 
and  constitutes  the  nucleus.  It  is  seen  to  be  divided  into  three 
equal  parts,  by  three  lines,  which  radiate  from  the  centre  to  within 
one-third  of  the  circumference.  Each  of  these  portions  is  com- 
posed of  numerous  concentric  layers,  arranged  one  within  the 
other,  like  the  coats  of  an  onion.  If  any  single  layer  be  examined 
with  the  microscope,  it  is  seen  to  be  composed  of  fibres  about 
5  pip  o th  of  an  inch  in  thickness,  running  in  a  curved  direction, 
and  connected  together  by  finely  serrated  edges.  On  a  transverse 
section  the  lens  fibres  are  found  to  be  hexagonal  prisms,  with  very 
little  connecting  substance.  Between  the  front  of  the  lens  and  its 
capsule  is  a  layer  of  flattened  cells  with  well-marked  excentric 
nuclei.  The  beautiful  dove-tailing  of  the  fibres  of  the  lens  was 
first  pointed  out  by  Sir  David  Brewster  ;  and  to  see  it  in  perfec- 
tion, one  ought  to  examine  the  lens  of  the  cod-fish. 

The  function  of  the  lens  is  to  bring  the  rays  of  light  to  a  focus 
upon  the  retina.* 

*  The  lens  contains  about  60  per  cent,  of  water,  and  30  per  cent  of  albuminoids. 


648 


DISSECTION  OF   THE  ORGAN  OF  HEARING. 

THE  parts  constituting  the  organ  of  hearing  should  be  examined 
in  the  following  order: — 1.  The  outer  cartilage  or  pinna  ;  2.  The, 
meatus  auditorius  externus  ;  which  leads  to  3.  The  tympanum  or 
middle  ear  ;  and  4.  The  labyrinth  or  internal  ear,  comprising  the 
vestibule,  cochlea,  and  semi-circular  canals. 

The  pinna  or  auricle  is  irregularly  oval,  and 
presents  on  its  external  aspect  numerous  eminences 
and  hollows,  which  have  received  the  following  names  : — The  cir- 
cumferential folded  border  is  called  the  helix ;  the  ridge  within  it, 
the  antihelix  ;  between  these  is  a  curved  groove,  called  the  fossa 
of  the  helix.  The  antihelix  bifurcates  towards  the  front,  and 
encloses  the  fossa,  of  the  antihelix.  The  conical  eminence  in  front 
of  the  meatus  is  termed  the  tragus,  on  which  some  hairs  are 
usually  found.  Behind  the  tragus,  and  separated  from  it  by  a 
deep  notch  (incisura  intertragica),  is  the  antitragus.  The  lobule 
is  the  soft  pendulous  part,  and  consists  of  fat  and  fibrous  tissue. 
The  deep  hollow,  which  collects  the  vibrations  of  sound,  and  con- 
veys them  into  the  external  meatus,  is  termed  the  concha.  The 
pinna  is  composed  of  yellow  fibre-cartilage,  with  a  little  fat  and 
cellular  tissue.  It  is  attached  by  an  anterior  ligament  to  the  root 
of  the  zygoma,  and  by  a  posterior  to  the  mastoid  process  of  the 
temporal  bone.  When  the  skin  of  the  pinna  is  removed,  we  find 
that  the  cartilage  has  a  tubular  prolongation  inwards,  which  forms 
the  external  part  of  the  meatus  auditorius.  It  does  not,  however, 
form  any  part  of  the  lobule,  and  is  incomplete  behind  the  tragus, 
the  deficiency  being  filled  up  with  fibrous  tissue.  The  cartilage 
further  presents  several  fissures  (fissures  of  Santorini)  at  the 
anterior  part  of  the  tubular  prolongation,  which  are  completed  by 
firm  fibrous  tissue. 


DISSECTION    OF    THE    ORGAN    OF    HEARING.  649 

MUSCLES  OF  The  muscles  which  move  the  cartilage  of  the 

THE  PINNA.  ear  as  a  wnole,  have  been  described  (p.  2).  Other 
small  muscles  extend  from  one  part  of  the  cartilage  to  another ; 
but  they  are  so  indistinct  that,  unless  the  subject  be  very  muscular, 
it  is  difficult  to  make  them  out.  The  following  six — four  on  the 
front  of  the  auricle  and  two  behind  it — are  usually  described : — 

(a.)  The    musculus   major  helicis  runs   vertically  along   the 

front  margin  of  the  helix. 
(6)  The  musculus  minor  helicis  lies  over  that  part  of  the 

helix  which  is  connected  with  the  concha. 

(c)  The  musculus  tragicus  lies  vertically  over  the  outer  surface 

of  the  tragus. 

(d)  The  'musculus  antitragicus  passes  transversely  from  the 

antitragus  to  the  lower  part  of  the  antihelix. 

(e)  The  musculus  transversus  is  on  the  cranial  aspect  of  the 

pinna ;  it  passes  nearly  transversely  from  the  back  of  the 
concha  to  the  helix. 

(/)  The    musculus    obliquus    extends    vertically  from    the 
cranial  aspect  of  the  concha  to  the  convexity  below  it. 

The  arteries  of  the  pinna  are  derived  from  the  posterior 
auricular,  and  from  the  auricular  branches  of  the  temporal 
and  occipital.  The  veins  empty  themselves  into  the  temporal 
vein.  The  nerves  are  furnished  by  the  auriculo-parotidean  branch 
of  the  superficial  cervical  plexus,  the  auriculo-temporal  branch  of 
the  inferior  maxillary,  the  posterior  auricular  branch  of  the  facial, 
and  the  auricular  branch  of  the  pneumogastric. 

MEATUS  AUDI-  This  passage  leads  down  to  the  membrana 
TOEIUS  EXTEBNUS.  tympani,  and  conveys  the  vibrations  of  sound  to 
the  tympanum.  It  is  about  an  inch  and  a  quarter  in  length  ;  its 
external  opening  is  longest  in  its  vertical  direction :  its  termina- 
tion is  broadest  in  its  transverse.  The  canal  inclines  at  first 
upwards  and  forwards,  and  then  curves  a  little  downwards.*  Its 

*  To  obtain  a  correct  knowledge  of  the  length  and  dimensions  of  the  meatus, 
sections  should  be  made  through  it  in  different  directions,  or  a  cast  be  taken  of  it  in 
plaster-of-Paris. 


650  DISSECTION   OF    THE    ORGAN   OF   HEARING. 

floor,  owing  to  the  "oblique  direction  of  the  membrana  tympani,  is 
a  little  longer  than  the  roof.  It  is  not  of  equal  calibre  throughout, 
the  narrowest  part  being  about  the  middle  ;  hence  the  difficulty 
of  extracting  foreign  bodies  which  have  passed  to  the  bottom  of  the 
canal.  It  is  formed,  partly  by  a  tubular  continuation  of  the 
cartilage  of  the  auricle,  partly,  by  an  osseous  canal  in  the  temporal 
bone.  The  cartilaginous  portion  is  about  half  an  inch  long  and 
is  firmly  connected  with  the  osseous  portion,  which  is  about  three- 
fourths  of  an  inch.  The  skin  and  the  cuticle  are  continued  down 
the  passage,  and  becoming  gradually  thinner,  form  a  cul-de-sac 
over  the  membrana  tympani.  The  outer  portion  is  furnished  with 
hairs  and  ceruminous  glands  which  secrete  the  cerumen  or  wax, 
and  are  only  found  over  the  cartilaginous  portion  of  the  canal.  Its 
arteries  are  derived  from  the  posterior  auricular,  internal  maxillary 
and  temporal ;  its  nerve  from  the  auriculo-temporal. 
T  The  tympanum,  or  middle  ear,  is  an  irregular 

cavity  in  the  petrous  part  of  the  temporal  bone, 
and  separated  from  the  external  auditory  meatus  by  the  membrana 
tympani.  It  is  lined  with  mucous  membrane  and  filled  with  air, 
which  is  freely  admitted  through  the  Eustachian  tube  ;  so  that 
the  atmospheric  pressure  is  equal  on  both  sides  of  the  membrane. 
A  chain  of  small  bones,  retained  in  their  position  by  ligaments 
and  acted  upon  by  muscles,  passes  across  it.  The  use  of  these 
bones  is  to  communicate  the  vibrations  of  the  membrana  tym- 
pani to  the  labyrinth.  For  this  purpose  one  end  of  the  chain  is 
attached  to  the  membrane,  the  other  to  the  fenestra  ovalis.  The 
antero- posterior  diameter  of  the  tympanum  is  rather  less  than  half 
an  inch,  its  vertical  and  transverse  diameters  about  a  quarter  of  an 
inch.  The  cavity  is  bounded  by  a  roof,  a  floor,  an  outer,  an  inner, 
an  anterior,  and  a  posterior  wall.  Its  roof  is  formed  by  a  thin 
plate  of  bone  corresponding  with  the  anterior  surface  of  the  pars 
petrosa  ;  its  floor,  by  a  thin  plate,  which  forms  the  jugular  fossa. 
Its  outer  wall  is  formed  by  the  membrana  tympani,  and  partly  by 
bone  ;  the  latter  is  pierced  by  the  fissura  Grlaseri  (which  gives  passage 
to  the  processus  gracilis  of  the  malleus  and  the  laxator  tympani), 
and  by  the  canal  of  Huguier  for  the  exit  of  the  chorda  tympani 


DISSECTION   OF   THE    OEGAN   OP   HEAEING.  651 

nerve.  The  inner  wall  presents  the  following  objects,  beginning 
from  above :  1.  A  ridge,  indicating  the  line  of  the  aqueductus 
Fallopii ;  2.  The  fenestra  ovalis,  which  leads  into  the  vestibule, 
but  is  closed  in  the  recent  state  by  a  membrane,  to  which  is 
attached  the  base  of  the  stapes ;  3.  Below  the  fenestra  ovalis  is  a 
bony  prominence,  the  promontory  ;  it  is  occasioned  by  the  first 
turn  of  the  cochlea,  and  is  marked  by  grooves,  in  which  lie  the 
branches  of  the  tympanic  plexus  of  nerves ;  4.  Below  and  behind 
this,  is  the  fenestra  rotunda ;  it  leads  into  the  scala  tympani  of 
the  cochlea,  but  is  closed  in  the  recent  state  by  membrane  ; 
5.  Immediately  behind  the  fenestra  ovalis,  is  a  small  conical 
eminence,  named  the  pyramid,  in  the  summit  of  which  is  a  small 
aperture,  from  which  the  tendon  of  the  stapedius  emerges. 

The  posterior  wall  presents  three  or  four  openings,  which 
lead  into  the  mastoid  cells,  and  convey  air  into  them  from  the 
tympanum  ;  also  a  small  foramen,  foramen  chordce  posterius,  for 
the  passage  of  the  chorda  tympani  nerve. 

The  anterior  wall  leads  to  the  Eustachian  tube,  and  (in  the  dry 
bone)  to  the  canal  for  the  tensor  tympani,  which  are  separated 
from  each  other  by  a  bony  septum,  the  processus  cochleariformis. 

Lastly,  a  nerve  called  the  chorda  tympani  (a  branch  of  the 
portio  dura)  runs  across  the  cavity,  covered  by  mucous  membrane. 
MEMBRANA  The  membrana  tympani  is  a  thin  semi- 

TYMPANI.  transparent  disk  which  completely  closes  the 

bottom  of  the  meatus  auditorius  externus.  It  is  nearly  circular, 
and  its  circumference  is  set  in  a  bony  groove,  so  that  it  is  stretched, 
somewhat  like  the  parchment  of  a  drum,  on  the  outer  wall  of  the 
tympanum.  Its  plane  is  not  vertical,  but  slants  from  above  down- 
wards, forming,  with  the  floor  of  the  meatus,  an  angle  of  55°. 
It  is  slightly  conical,  the  apex  being  directed  inwards  towards  the 
tympanum,  and  between  its  layers  is  inserted  the  handle  of  the 
malleus.  It  is  composed  of  three  layers :  an  outer,  formed  by 
an  extremely  thin  layer  of  true  skin ;  an  inner,  by  the  mucous 
membrane  of  the  tympanum ;  and  a  middle  layer,  consisting  of 
fibrous  tissue  ;  some  of  the  fibres  radiate  from  the  centre,  others 
are  circular,  forming  a  circumferential  ring  close  to  the  osseous 


652  DISSECTION  or  THE  ORGAN  OP  HEAKING. 

groove.  The  membrane  is  supplied  with  blood  from  the  tympanic 
branch  of  the  internal  maxillary,  the  stylo-mastoid  branch  of  the 
posterior  auricular,  and  the  Vidian. 

EUSTACHIAN  For  a  complete  account  of  the  Eustachian  tube 

TUBE.  (see  p.  186).     It  proceeds  from  the  anterior  part 

of  the  tympanum,  downwards,  forwards,  and  inwards,  to  the 
pharynx. 

OSSICULA  The  three  small  bones  in  the  tympanum  are 

AUDITUS.  named  after  their  fancied  resemblance  to  certain 

implements,  the  malleus,  incus,  and  stapes.     They  are  articulated 
FIG.  165.  to  each  other  by  perfect  joints,  and  are  so 

placed  that  the  chain  somewhat  resembles 
the  letter  Z.     Their  use  is  to  transmit  the 
vibrations  of  the  membrana  tympani  to  the 
membrane  of  the  fenestra  ovalis,  and,  through 
it,  to  the  fluid  contained  within  the  vestibule. 
But  they  have  another  use,  which  would  be 
THE  OSSICLES  OF  THE  EIGHT  incompatible  with   a  single  bone — namely, 
TYMPANUM.  to  permit  the  tightening  and  relaxation  of 

A.  Malleus.    B.  Incns.  ,,  ,  ,    ,,  ,       ,     .,        .,, 

c.  stapes,  it  lies  horizontally  the  membrane,  and  thus  adapt  it  either  to 

and  forms  a  right  angle  with  .in-  if  i  •> 

the  long  process  of  the  incus,  resist  the  impulse  of  a  very  loud  sound,  or 
to  favour  a  more  gentle  one. 

The  malleus,  or  hammer  bone,  consists  of  an  upper  part  or 
head,  which  is  suspended  to  the  roof  of  the  tympanum  by  the  sus- 
pensory ligament,  and  articulates  posteriorly  with  the  incus.  From 
it  proceeds  the  handle,  which  is  nearly  vertical,  and  is  attached 
along  its  whole  length  to  the  upper  half  of  the  membrana  tympani. 
The  long  process  (processus  gracilis)  projects  at  right  angles  from 
the  head  of  the  malleus,  runs  into  the  Grlaserian  fissure,  and 
receives  the  insertion  of  the  laxator  tympani.  The  processus 
brevis,  situated  at  the  junction  of  the  long  process  and  the  head, 
looks  towards  the  membrana  tympani,  and  receives  the  insertion  of 
the  tensor  tympani. 

The  incus,  or  anvil  bone,  is  shaped  like  a  tooth  with  two  unequal 
widely  separated  fangs.  Its  broad  part  or  body  presents  a  concavo- 
convex  articulation  for  the  head  of  the  malleus ;  its  long  process 


DISSECTION    OF    THE    OEGAN    OF    HEABING.  653 

runs  nearly  parallel  with  the  handle  of  the  malleus,  and  articulates 
with  the  stapes  through  the  intervention  of  a  small  bone,  the  os 
orbiculare,  which,  in  adult  life,  forms  part  of  the  long  process,  but 
in  foetal  life  is  a  separate  bone ;  its  short  process  is  directed  back- 
wards, and  its  point  is  fixed  in  a  small  hollow  at  the  commence- 
ment of  the  mastoid  cells. 

The  stapes,  or  stirrup  bone,  lies  horizontally.  Its  head  articulates 
with  the  long  process  of  the  incus.  Two  diverging  crura  pass 
from  the  head  to  the  base,  which  is  attached  to  the  membrane 
covering  the  fenestra  ovalis.  The  stapedius  muscle  is  inserted 
into  the  posterior  part  of  its  neck. 

The  tympanic  bones  are  maintained  in  their  positions  by 
various  ligaments.  The  anterior  ligament  of  the  malleus  passes 
from  the  head  of  this  bone  to  the  anterior  wall  of  the  tympanum  ; 
the  suspensory  ligament  descends  from  the  roof  of  the  tympanum 
outwards  to  the  head  of  the  malleus,  and  the  posterior  ligament 
of  the  incus  passes  from  the  short  process  to  the  posterior  wall  near 
the  mastoid  cells.  The  ossicles  are  connected  by  an  imperfect 
capsular  ligament,  which  passes  from'  the  long  process  of  the 
incus  to  the  head  of  the  stapes ;  and  by  another  which  passes 
from  the  head  of  the  malleus  to  the  incus.  The  surfaces  of  the 
bones  forming  these  two  little  joints  are  covered  with  cartilage. 
The  joints  have  also  synovial  membranes. 

The  muscles,  by  moving  the  tympanic  bones,  tighten  or  relax 
MUSCLES  OF  the  membrana  tympani.  The  tensor  tympani 
THE  TYMPANUM.  runs  in  a  canal  above  and  parallel  to  the  Eustachian 
tube,  from  the  cartilaginous  part  of  which  it  arises,  as  well  as  from 
the  apex  of  the  petrous  portion  of  the  temporal  bone.  It  passes 
backwards,  and  terminates  in  a  round  tendon,  which  enters  the 
front  wall  of  the  tympanum  through  a  special  bony  canal,  and  is 
inserted  into  the  root  of  the  handle  of  the  malleus.  Its  nerve 
comes  from  the  otic  ganglion.  Its  action  is  to  draw  inwards  the 
head  of  the  malleus,  and  thus  render  the  membrane  tense.  The 
laxator  tympani  arises  from  the  spinous  process  of  the  sphenoid, 
and  the  Eustachian  tube,  and  is  inserted  into  the  neck  of  the 
malleus  close  to  the  root  of  the  processus  gracilis.  It  is  supplied 


654  DISSECTION    OP    THE    ORGAN    OF    HEARING. 

by  a  branch  of  the  facial  nerve.*  Its  action  is  to  relax  the  mem- 
brana  tympani.  The  stapedius  arises  from  the  hollow  of  the 
pyramid,  and  its  tendon  runs  forwards  to  be  inserted  into  the 
neck  of  the  stapes,  f  Its  nerve  is  derived  from  the  facial.  By 
its  action  it  increases  the  tension  upon  the  fluid  in  the  vestibule. 

The  tympanum  is  lined  with  mucous  membrane,  which  is 
continuous  with  that  of  the  pharynx.  It  covers  the  ossicles,  and 
is  prolonged  into  the  mastoid  cells.  The  membrane  is  pale  and 
thin,  and  lined  with  columnar  ciliated  epithelium,  except  on  the 
promontory,  the  membrana  tympani,  and  the  ossicles,  where  there 
is  only  a  single  layer  of  flattened  cells. 

CHORDA  TTM-  A  branch  (chorda  tympani)  of  the  facial  nerve 

PANI.  enters  the  tympanum  through  a  foramen  at  the 

base  of  the  pyramid  (foramen  chordae  posterius) ;  it  then  crosses 
the  tympanum  between  the  handle  of  the  malleus  and  the  long 
process  of  the  incus,  leaves  the  tympanum  through  a  foramen 
(foramen  chordae  anterius),  and  then  traverses  a  canal  (canal  of 
Huguier\vfhich  runs  close  to  the  Grlaserian  fissure.  It  eventually 
joins  the  submaxillary  ganglion  (p.  51). 

BLOOD-VESSELS         The  tympanum  is  supplied  with  blood— 1,  by 
OF  THE  TYM-  the  tympanic  branch  of  the  internal  maxillary, 

PANTJM.  which  enters  through  the  fissura  Grlaseri ;  2,  by 

the  stylo-mastoid  branch  of  the  posterior  auricular ;  3,  by  small 
branches  from  the  ascending  pharyngeal,  which  enter  with  the 
Eustachian  tube  ;  4,  by  branches  from  the  internal  carotid  artery  ; 
and  5,  by  the  petrosal  branch  of  the  arteria  meningea  media. 

The  mucous  membrane  is  supplied  with  branches  from  the 
tympanic  plexus,  which  is  formed  by  filaments  from  the  tympanic 
branch  of  the  glosso-pharyngeal  nerve,  from  the  carotid  sympathetic 
plexus,  and  from  the  large  and  small  superficial  petrosal  nerves. 

This,  in  consequence  of  its  complexity,  is  called 

INTERNAL  EAR.  7    ,        .      ,        1.  r  •" 

the  Labyrinth.     It  consists  01  cavities  excavated 

*  This  is  usually  regarded  as  a  muscle,  and  is  described  here  as  such ;  no  mus- 
cular fibres,  however,  can  be  traced  in  it,  so  that  it  is  probably  only  ligamentous  in 
structure — a  fact  borne  out  in  the  lower  animals. 

f  There  is  a  little  sheath,  lined  with  synovial  membrane,  to  facilitate  the  play  of 
the  tendon  in  the  pyramid. 


DISSECTION    OF    THE    ORGAN    OF    HEARING. 


655 


in  the  most  compact  part  of  the  temporal  bone.  The  cavities  are 
divided  into  three — a  middle  one,  called  the  vestibule,  being  a 
centre  in  which  all  communicate ;  an  anterior,  named  from  its 
resemblance  to  a  snail's  shell,  the  cochlea ;  and  a  posterior,  con- 
sisting of  three  semicircular  canals.  These  cavities  are  filled  with 
a  clear  fluid,  called  the  endo-lymph,  and  contain  a  membranous 
expansion  (the  membranous  labyrinth),  upon  which  the  filaments 
of  the  auditory  nerve  are  expanded. 

The  vestibule,  or  central  chamber,  is  an  irregular 
oblong  cavity,  about  one-fifth  of  an  inch  in  its 
widest  part.     It  communicates  in  front  with  the  cochlea,  through 

FIG.  166. 


VESTIBULE. 


1.  The     superior    semicir- 

cular canal. 

2.  The   posterior    semicir- 

cular canal. 

3.  The     external    semicir- 

cular canal. 

4.  Common  opening  of  the 

superior  and   posterior 
semicircular  canals. 


5.  Aqueductus  vestibuli. 

6.  Aqueductus  cochleae. 

7.  Fovea  hemi-elliptica. 

8.  Fovea  hemispherica. 

9.  Scala  tympani. 
10.  Scala  vestibuli. 


OSSEOUS    LABYRINTH   OF   THE    EIGHT    SIDK 


the  scala  vestibuli  ;  behind,  with  the  five  openings  of  the  semi- 
circular canals  ;  on  the  outside  with  the  tympanum,  through  the 
fenestra  ovalis  ;  on  the  inside  is  a  shallow  depression,  the  fovea 
hemispherica,  through  which  are  transmitted  the  branches  of  the 
auditory  nerve.  Posteriorly,  this  depression  is  bounded  by  a  ridge, 
the  crista  vestibuli,  and  in  some  subjects  there  is  behind  this 
eminence  the  opening  of  a  small  canal,  called  the  aqueductus 
vestibuli.  It  leads  to  the  posterior  surface  of  the  temporal  bone, 
and  transmits  a  small  vein.  In  the  roof  is  an  oval  depression,  the 
fovea  hemi-elliptica,  which  lodges  the  utricle. 

SEMICIRCULAR  The  semicircular  canals,  three  in  number,  are 

CANALS.  situated  above,  and  rather  behind  the  vestibule. 


656  DISSECTION    OF    THE    ORGAN   OF   HEARING. 

Each  canal  forms  about  two-thirds  of  a  circle,  and  is  about  one- 
twentieth  of  an  inch  in  diameter.  They  open  at  each  extremity 
into  the  vestibule,  therefore  there  should  be  six  apertures  for  them  ; 
but  there  are  only  five,  since  one  of  the  apertures  is  common  to 
the  extremities  of  two  canals.  The  canals  are  not  of  equal 
diameter  throughout ;  each  presents  at  one  end  a  dilatation  termed 
the  ampulla,  about  one-tenth  of  an  inch  in  diameter.  This  dila- 
tation corresponds  to  a  similar  dilatation  of  the  membranous  sac, 
upon  which  the  auditory  nerve  expands.  Each  canal  differs  in  its 
direction ;  they  are  named  accordingly,  superior,  posterior,  and 
external.  The  superior  s.  c.  is  also  the  most  anterior  of  the  three  ; 
its  direction  is  vertical,  and  runs  across  the  petrous  bone ;  the 
ampulla  is  at  the  outer  extremity.  Its  non-ampullated  extremity 

FIG.  167. 


1.  Scala  tympani.  B^^iMiH^^  3.  Lamina  spiralis 

~L-^4^KhEJ3  Hn  ossea. 

2.  Scala  vestibuli.  ^3S§.H  Bp — * 

4.  Modiolus,  or  central 
pillar. 


THE   OSSEOUS    COCHLEA. 

opens  by  a  common  orifice  with  the  posterior  s.  c.  The  posterior 
s.  c.  is  also  vertical,  runs  parallel  to  the  posterior  surface  of  the 
petrous  bone,  and  consequently,  at  right  angles  to  the  preceding ; 
the  ampulla  is  at  the  lower  end.  The  external  s.  c.  is  horizontal 
in  position,  with  the  convexity  of  the  arch  directed  backwards ;  the 
ampulla  is  at  the  outer  end. 

The  cochlea  is  the  most  anterior  part  of  the 
internal  ear  :  it  very  closely  resembles  a  common 
snail's  shell,  and  is  placed  so  that  the  base  of  the  shell  corresponds 
to  the  bottom  of  the  meatus  auditorius  internus,  while  the  apex 
is  directed  forwards  and  outwards.  Its  base  is  about  a  quarter  of 
an  inch  in  diameter.  It  consists  of  the  spiral  convolutions  of  two 
parallel  and  gradually  tapering  tubes,  which  wind  round  a  central 
pillar,  called  the  modiolua.  The  partition  by  which  the  tubes, 


DISSECTION    OF    THE    ORGAN    OF    HEARING.  657 

scalce,  are  separated  is  termed  the  lamina  spiralis.  In  the  dry 
bones  this  partition  is  only  partial ;  but  in  the  recent  state  it 
is  completed  by  a  membrane.  The  spiral  canal  is  about  the  T^  of 
an  inch  in  diameter,  and  is  about  one  inch  and  a  half  long,  and, 
after  making  two  turns  and  a  half,  terminates  at  the  apex  of  the 
cochlea  in  a  rounded  dome,  the  cupola.  Here  the  partition  dis- 
appears, and  is  called  the  helicotrema,  so  that  the  two  scalae  com- 
municate with  each  other  in  this  situation.  These  tubes  are 
called  the  scales  of  the  cochlea,  and  are  filled  with  fluid.  The 
upper  one,  the  scala  vestibuli,  opens  into  the  vestibule ;  the 
lower  one,  rather  the  larger  of  the  two,  is  called  the  scala  tym- 
pani,  and  leads  to  the  membrane  which  closes  the  foramen  ro- 
tundum  of  the  tympanum.  At  its  commencement  there  is  the 
opening  of  the  aqueductus  cochleae,  which  transmits  a  small 
branch  to  the  jugular  vein. 

The  central  pillar  of  the  cochlea  is  called  the  modiolus.  It 
is  of  considerable  thickness  at  the  base,  but  gradually  tapers 
towards  the  apex.  Its  interior  is  traversed  by  numerous  canals, 
which  transmit  small  vessels  and  nerves  to  the  lamina  spiralis. 
One  of  these  canals,  larger  than  the  others,  runs  down  the  centre 
of  the  modiolus  nearly  to  the  apex,  and  transmits  a  small  artery, 
the  arteria  centralis  modioli. 

The"  lamina  spiralis,  the  partition  between  the  two  tubes  or 
scales  of  the  cochlea,  is  made  up,  on  the  inner  half,  of  bone, 
(lamina  spiralis  ossea} ;  on  the  outer  half,  of  membrane,  which, 
as  will  be  presently  described,  consists  of  two  layers.  The  lamina 
spiralis  ossea  ends  at  the  cupola  in  a  hook-line  process,  the  hamulus. 
On  a  vertical  section  it  is  seen  to  be  composed  of  two  plates, 
between  which  the  structure  is  spongy,  and  presents  a  number  of 
small  canals  for  the  passage  of  the  small  filaments  of  the  cochlear 
division  of  the  auditory  nerve  in  their  course  to  the  membranous 
part  of  the  lamina.  Winding  round  the  modiolus,  close  to  the 
attachment  of  the  lamina  spiralis  ossea,  is  a  small  canal,  called  the 
canalis  spiralis  modioli. 

MEMBRANOUS  If  the  bony  labyrinth  just  described  be  properly 

LABYEINTH.  understood,  there  will  not  be  much  difficulty  in 

u  u 


658  DISSECTION    OP   THE    ORGAN   OF    HEARING. 

comprehending  the  shape  of  the  membranous  labyrinth  in  its 
interior, —  a  structure  supporting  the  ultimate  ramifications  of  the 
auditory  nerve.  The  membranous  labyrinth  floats  in  a  fluid 
called  the  peri-lymph  or  liquor  Cotunnii,  which  is  secreted  by  the 
delicate  serous  membrane  lining  the  osseous  labyrinth. 

The  membranous  labyrinth  is  a  sac,  contained  partly  in  the 
vestibule  and  partly  in  the  semicircular  canals :  that  situated  in 
the  vestibule  is  termed  the  vestibular  portion  ;  that  in  the  bony 
canals,  the  membranous  semicircular  canals. 

The  sac  in  the  vestibule  is  so  constructed  as  to  form  two  sacs 
of  unequal  size,  which  indirectly  communicate  with  each  other.* 
The  larger  of  the  two,  called  the  utricle  or  common  sinus,  is 
oval,  and  communicates  with  the  five  openings  of  the  membranous 
semicircular  canals.  It  is  lodged  in  the  fovea  hemielliptica,  and 
its  wall  is  thickest  close  to  the  crista  vestibuli,  where  branches  from 
the  auditory  nerve  enter  it.  The  smaller,  called  the  saccule,  is 
globular  and  flattened,  and  lies  in  the  fovea  hemispherica,  in  front 
of  the  utricle.  It  is  connected  with  the  membranous  canal  of  the 
cochlea  by  a  small  short  duct,  termed  ihe~canalis  reuniens. 

The  utricle  and  the  saccule  contain  on  their  inner  wall  a  minute 
mass  of  calcareous  matter  in  connection  with  nerve  ends,  called 
by  Breschet  the  otoliths  or  otoconia.  They  are  crystals  of  car- 
bonate of  lime,  and  are  present  in  the  labyrinth  of  all  mammalia. 
From  their  greater  hardness  and  size  in  aquatic  animals,  there  is 
reason  to  believe  that  they  perform  the  office  of  rendering  the 
vibrations  of  sound  sharper  and  more  distinct.f 

MEMBRANOUS  The   membranous   semicircular   canals   present 

SEMICIRCULAR          the  same  dilatations  or  ampullas  as  the  bony  ones, 

at  one  end,  and  at  this  part  they  nearly  fill  their 

*  From  the  utricle  there  proceeds  a  small  canal,  -which  lies  in  the  aqueductus 
vestibuli ;  this  is  joined  close  to  its  commencement  by  a  similar  canal  from  the 
saccule ;  thus  forming  the  indirect  communication  above  alluded  to. 

t  For  a  detailed  description  of  the  relation  of  the  otoliths  with  the  hair-like 
processes  of  the  nerve-filaments,  the  student  is  referred  to  an  article  by  Dr.  Urban 
Pritchard  in  the  'Quarterly  Journal  of  Microscopic  Science,'  October,  1876,  entitled 
'The  Termination  of  the  Nerves  in  the  Vestibule,  and  Semicircular  Canals  of 
Mammals.' 


DISSECTION    OF   THE    OUGAN    OP    HEARING.  659 

bony  cases  ;  but  in  the  rest  of  their  extent  the  diameter  of  the 
membranous  canal  is  not  more  than  one-third  that  of  the  bony. 
At  the  ampullated  extremity  the  sac  is  connected  on  its  outer 
aspect  by  blood-vessels  and  nerves  to  the  periosteum,  forming,  on 
section,  a  septum,  called  the  septum  transversum. 

The  membranous  labyrinth  is  protected,  inside  and  out,  by 
fluid.  The  fluid  in  the  interior  is  termed  the  endolymph,  and 
the  thin  layer  between  it  and  the  bone,  the  perilymph  or  liquor 
Cotunnii',  thus  the  delicate  nervous  membrane  is  placed  between 
two  layers  of  fluid. 

DISTRIBUTION  The   auditory   nerve    or    portio   mollis   of  the 

OF  THE  AUDITORY  seventh  pair,  passes  down  the  jneatus  auditorius 
internus,  and  at  the  bottom  of  it,  divides  into  an 
anterior  and  posterior  branch,  which,  after  breaking  up  into 
numerous  fasciculi,  are  distributed  to  the  cochlea  and  to  the 
vestibule. 

The  vestibular  nerve  divides  into  five  branches,  which  pro- 
ceed to  the  utricle,  the  saccule,  and  the  three  ampullae  of  the 
semicircular  canals,  respectively :  those  for  the  utricle,  and  the 
superior  and  external  semicircular  canals  enter  the  vestibule  along 
the  crista  vestibuli ;  that  for  the  saccule  enters  through  the  fovea 
hemispherica,  and  that  for  the  posterior  semicircular  canal  is  con- 
tinued along  a  bony  canal  to  its  termination.  The  nerves  to  the 
semicircular  canals  enter  the  ampullae  by  a  forked  swelling  which 
corresponds  to  each  septum  transversum. 

The  membranous  semicircular  canals  consist  of  three  layers, 
an  outer  or  fibrous  layer,  which  is  connected  with  the  periosteum 
by  blood-vessels,  and  contains  irregular  pigment-cells  ;  a  middle  or 
tunica  propria,  clear  and  structureless ;  and  an  inner  or  epithelial 
layer,  which  lines  the  inner  space  of  the  tunica  propria.  At  the 
ampullse  the  epithelial  layer  is  composed  of  the  columnar  variety, 
upon  which  are  arranged  cells  of  a  spindle  shape,  having  delicate 
ciliated  processes  (auditory  hairs}  projecting  into  the  endolymph. 

It  has  been  stated  that  in  the  bony  cochlea  there  is  a  partial 
septum,  dividing  the  spiral  tube  into  two  incomplete  scalae.  In  the 
recent  condition,  however,  the  osseous  lamina  spiralis  is  continued 

ru  2 


660  DISSECTION    OF   THE    ORGAN    OF   HEARING. 

outwards  by  a  thick  membrane,  the  basilar  membrane  (fig.  168)  ; 
thus  dividing  the  tube  into  an  upper  canal,  the  scala  vestibuli, 
and  a  lower,  the  scala  tympani.  The  upper  scale  is  subdivided  by 
an  oblique  membrane — membrane  of  Reissner — into  two  canals, 
an  inner,  the  scala  vestibuli)  and  an  outer,  the  ductus  cochlearis. 
The  ductus  cochlearis  or  scala  media  terminates  at  the  helicotrema 
in  a  cul-de-sac ;  inferiorly  it  is  connected  with  the  cavity  of  the 
saccule  by  a  long,  narrow  duct,  called  the  canalis  reuniens. 

On  examining  the  membranous  continuation   of  the  lamina 
spiralis,  it  is  seen,  not  far  from  its  attachment  to  the  osseous  zone, 

FIG.  168. 


DIAGRAMMATIC    SECTION    OF   A    COIL    OF    THE    COCHLEA. 

(From  Quain.) 

s  v.  Scala  vestibuli.  r  c.  Rods  of  Corti. 

D  c.  Ductus  cochlearis.  m  b.  Membrana  basilaris. 

S  T.  Scala  tympani.  Is  p.  Ligamentum  spirale. 

m  H.  Membrane  of  Beissner.  s  s.  Sulcus  spiralis. 

Us.  Limbus  laminae  spiralis.  g  s.  Ganglion  spirale. 
m  T.  Membrana  tectoria. 

to  be  thickened  into  an  elongated  crest,  the  limbus,  which  over- 
hangs a  groove,  called  the  sulcus  spiralis.  The  structure  of  the 
limbus  consists  of  firm  connective  tissue,  on  the  under  part  of  which 
are  found  numerous  cells.  The  basilar  membrane  forms,  at  the 
base  of  the  cochlea,  but  a  small  breadth  of  the  septum,  the  broadest 
part  being  formed  of  bone,  but  it  gradually  increases  in  breadth 
towards  the  cupola,  where  it  constitutes  nearly  the  entire  septum. 


DISSECTION    OF   THE   ORGAN   OP   HEARING.  661 

It  consists  of  a  firm,  fibrillated  tissue,  which  is  probably  formed,  at 
any  rate  on  its  upper  surface,  of  a  structure  closely  resembling 
the  organ  of  Corti. 

The  membrane  which  separates  the  scala  vestibuli  and  the 
ductus  cochlearis  is  a  delicate  almost  structureless  layer,  the  mem- 
brane of  Reissner.  It  appears  to  be  composed  of  connective  tissue, 
lined  on  its  vestibular  surface  with  flattened  connective -tissue 
cells,  and  on  its  cochlear  surface  with  squarnous  epithelium. 

At  the  point  of  attachment  of  the  basilar  membrane  with  the 
outer  wall  of  the  cochlea  may  be  seen  a  triangular  projection,  which, 
formerly  described  as  a  muscle,  (cochlearis  musvle),  is  now  generally 
believed  to  be  a  collection  of  connective-tissue  cells,  and  called 
the  ligamentum  spirale. 

OHGAK  OF  The  organ  of  Corti  is  a  highly  complex  structure, 

COBTI-  placed  on  the  upper  surface  of  the  basilar  mem- 

brane, and  the  floor  of  the  ductus  cochlearis.  The  central  part  of 
the  organ  of  Corti  is  formed  by  two  sets  of  slanting  rods — inner 
and  outer  rods  of  Corti*  which  rest  against  each  other  at  their 
upper  extremities,  thus  forming  a  triangular  tunnel  beneath  them, 
filled  in  the  recent  state  with  endolymph. 

On  the  inner  side  of  the  inner  rods  is  a  single  row  of  cells 
tipped  with  ciliated  processes,  called  the  inner  hair-cells  ;  and  on 
the  outer  side  of  the  outer  rods  are  three  rows  of  similar  cells, 
termed  the  outer  hair-cells. 

The  only  remaining  membrane  to  be  described  is  the  tectorial 
membrane)  which  lies  above  and  parallel  to  the  basilar  membrane, 
but  does  not  extend  much  more  than  half-way  over  it.  It  is  con- 
nected on  its  inner  side  with  the  limbus  spiralis,  and  is  then  con- 
tinued outwards,  overlying  and  resting  upon  the  rods  of  Corti, 
and  ends  in  a  free  extremity.  It  is  a  strong,  elastic  membrane, 
distinctly  fibrous,  especially  upon  its  inner  and  thicker  part. 

The  cochlear  division  of  the  auditory  nerve  (the  vestibular  has 
already  been  described, p.  659)  is  a  short,  thick  branch,  which  breaks 
up  into  numerous  filaments  at  the  bottom  of  the  meatus  auditorius 

*  The  inner  rods  are  stated  to  be  more  numerous  than  the  outer,  in  the  proportion 
of  6,000  of  the  inner  to  4,500  of  the  outer  rods. 


662 

interims.  These  enter  the  canals  in  the  base  of  the  modiolus,  and 
then  arch  outwards  between  the  plates  of  the  lamina  ossea.  In 
their  course  outwards  between  the  plates,  they  pass  through  the 
spirally  arranged  ganglionic  cells,  beyond  which  they  form  a  wide 
plexus.  They  are  collected  together  close  to  the  free  border  of  the 
osseous  zone,  forming  a  very  minute  nerve-plexus,  whose  filaments 
interlace  freely  ;  they  then  enter  the  membranous  zone  to  be  con- 
nected with  the  inner  hair-cells  of  the  organ  of  Corti.* 

The  vessels  which  supply  the  cochlea  are  from  ten  to  twelve  in 
number,  and  are  derived  from  the  auditory  artery  ;  they,  like  the 
nerves,  enter  the  bony  canals  of  the  modiolus,  and  then  turn  out- 
wards to  ramify  upon  the  osseous  zone,  supplying  its  periosteum. 
The  plexus  formed  by  these  branches  communicates  with  a  vessel 
known  as  the  vas  spirale,  which  runs  longitudinally  in  the  liga- 
mentum  spirale  to  the  outer  attachment  of  the  membrana  basil- 
aris.  The  veins  from  the  cochlea  terminate  in  the  superior 
petrosal  sinus,  having  previously  joined  those  of  the  vestibule  and 
semicircular  canals. 

*  Some  anatomists  describe  filaments  as  passing  between  the  rods  of  Corti  to  end 
in  the  outer  hair-cells^ 


663 


DISSECTION  OF  THE  MAMMARY  GLAND. 

THE  form,  size,  position,  and  other  external  characters  of  the 
mammary  gland  vary  more  or  less  in  different  persons.  The 
longest  diameter  of  the  gland  is  in  a  direction  upwards  and  out- 
wards towards  the  axilla ;  its  thickest  part  is  at  the  centre  ;  and 
the  fulness  and  roundness  of  the  gland  depend  upon  the  amount 
of  fat  about  it.  Its  deep  surface  is  flattened  in  adaptation  to 
the  pectoral  muscle,  to  which  it  is  firmly  connected  by  an  abund- 
ance of  areolar  tissue.  In  its  vertical  direction  the  breast  corre- 
sponds to  the  space  between  the  third  and  sixth  or  seventh  ribs ; 
in  its  lateral  direction,  to  the  space  between  the  side  of  the 
sternum  and  the  axilla,  while  the  nipple  corresponds  to  the  fourth 
rib,  or  a  little  below  it. 

It  is  enclosed  by  a  fascia,  which  not  only  supports  it  as  a 
whole,  but  penetrates  into  its  interior,  so  as  to  form  a  framework 
for  its  several  lobes  ;  hence  it  is  that,  in  cases  of  mammary  abscess, 
the  matter  is  apt  to  be  circumscribed,  not  diffused. 

The  nipple  (mammilla)  projects  a  little  below  the  centre ;  it. 
is  surrounded  by  a  coloured  circle,  termed  the  areola ;  this  circle 
is  of  a  rose-pink  colour  in  virgins,  but,  in  those  who  have  borne 
children,  of  a  dark  brown.  It  begins  to  enlarge  and  grow  darker 
about  the  second  or  third  month  of  pregnancy,  and  these  changes 
continue  till  parturition.  The  areola  is  abundantly  provided  with 
papillae,  and  with  subcutaneous  sebaceous  glands,  to  lubricate 
the  surface  during  lactation ;  the  areola  as  well  as  the  nipple  is 
destitute  of  fat. 

The  gland  itself  consists  of  distinct  lobes  held 

together  by  firm  connective  tissue,  and  provided 

with  separate  lactiferous  ducts.     Each  lobe  divides  and  subdivides 


664  DISSECTION   OF   THE    MAMMARY   GLAND. 

into  lobules,  and  the  duct  branches  out  accordingly.*  Traced  to 
their  origin,  we  find  that  the  ducts  commence  in  clusters  of 
minute  cells,  and  that  the  blood-vessels  ramify  minutely  upon 
these  cells ;  altogether,  then,  a  single  lobe  might  be  compared  to 
a  bunch  of  grapes,  of  which  the  stalk  represents  the  main  duct. 
The  main  ducts  (galactophorus  ducts}  from  the  several  lobes, 
from  fifteen  to  twenty  in  number,  converge  towards  the  nipple, 
and,  just  before  they  reach  it,  become  dilated  into  small  sacs  or 
ampullce,  two  or  three  lines  wide ;  after  this  they  run  up  to  the 
apex  of  the  nipple,  and,  running  parallel,  terminate  in  separate 
orifices. 

The  vesicles  and  the  galactophorus  ducts  are  lined  with 
columnar  epithelium,  except  at  their  orifices,  where  it  becomes 
squamous. 

The  arteries  of  the  gland  are  derived  from  the  long  thoracic, 
the  internal  mammary,  and  the  intercostals ;  the  nerves  come 
from  the  anterior  and  lateral  cutaneous  branches  of  the  intercostal 
nerves  and  from  the  descending  branches  of  the  cervical  plexus. 
The  veins  diverge  from  the  nipple,  and  terminate  in  the  axillary 
and  internal  mammary  veins. 

The  lymphatics  run  chiefly  to  the  axillary  glands. 

*  It  is  observed,  in  some  cases,  that  one  or  more  lobules  run  off  to  a  consider- 
able distance  from  the  main  body  of  the  gland,  and  lie  embedded  in  the  subcutaneous 
tissue.  This  should  be  remembered  when  it  is  necessary  to  remove  the  entire 
gland. 


665 


DISSECTION  OF  THE  SCROTUM   AND   TESTIS. 

STRUCTURE  OF  THE  scrotum  is  a  pouch  of  skin  for  the  lodgment 
THE  SCROTUM.  of  the  testes,  and  presents  in  the  middle  line  a  ridge, 
the  raphe,  on  each  side  of  which  it  is  corrugated  into  rugae.  It 
is  composed  of  six  tunics: — 1.  The  skin;  2.  The  tunica  dartos ; 
3.  A  layer  of  connective  tissue ;  4.  The  spermatic  fascia ;  5.  The 
cremaster  or  suspensory  muscle  ;  6.  The  infundibuliform  fascia, 
derived  from  the  fascia  transversalis. 

Each  of  these  coverings  cannot  be  demonstrated  under  ordi- 
nary circumstances,  because  they  are  so  blended  together ;  but  they 
can  be  shown  when  hypertrophied  in  the  case  of  old  and  large 
herniae. 

The  dartos  is  a  thin  layer,  consisting  of  mus- 
Z)AETOS 

cular  fibres  of  the  involuntary  kind,  like  those  of 

the  bladder  and  intestines.  It  serves  to  corrugate  the  loose  and 
extensible  skin  of  the  scrotum,  and  in  a  measure  to  support  and 
brace  the  testicles.  It  is  more  abundant  in  the  anterior  than  the 
posterior  part  of  the  scrotum. 

LAYER  OF  CON-  Beneath  the  dartos  is  a  large  quantity  of  loose 
NECTIVE  TISSUE.  connective  tissue,  remarkable  for  the  total  absence 
of  fat.  Together  with  the  dartos,  it  forms  a  vertical  partition 
between  the  testicles,  termed  the  septum  scroti.  It  is  not  a  com- 
plete partition,  since  air  or  fluid  will  pass  from  one  side  to  the 
other.  The  great  abundance  and  looseness  of  this  tissue  explains 
the  enormous  swelling  of  the  scrotum  in  cases  of  anasarca,  and  in 
cases  where  the  urine  is  effused  into  it  in  consequence  of  rupture 
or  ulceration  of  the  urethra. 

The  spermatic  fascia,  cremaster  muscle,  and  the  infundibuli- 
form fascia  have  been  described  (pp.  359,  361,  366). 


666 


DISSECTION   OF   THE    TESTIS. 


TESTIS. 


The  testicle  is  a  gland  of  an  oval  shape  with 
flattened  sides,  suspended  obliquely,  so  that  the 
upper  end  is  directed  forwards  and  outwards,  the  lower  end  in  the 
reverse  direction.  The  left  is  generally  a  little  the  lower  of  the 
two.  Each  testis  is  about  an  inch  and  a  half  in  length,  and  one 
in  breadth,  and  weighs  about  six  drachms  ;  but  few  organs  present 
greater  variations  in  size  and  weight,  even  in  men  of  the  same 
age ;  generally  speaking,  the  left  is  the  larger.  The  front  and 
sides  of  the  testes  are  smooth,  and  covered  with  the  visceral  layer 
of  the  tunica  vaginalis ;  but  along  the  posterior  part  of  the  gland 

FIG.  169. 


1.  Mediastinum    testis,  con- 

taining the  rete  testis. 

2,  2.  Trabeculse. 

3.  One  of  the  lobules. 

4,  4.  Vasa  recta. 


5.  Coni  vasculosi,  forming  the 

'  globus  major'  of  the  epi- 
didymis. 

6.  Globus  minor,  or  lower  end 

of  epididymis. 

7.  Vas  deferens. 


DIAGEAM    OF   A    VERTICAL   SECTION    THROUGH    THE    TESTICLE. 


EPIDIDYMIS. 


is  placed  a  long  narrow  body,  termed  the  epididy- 
mis ;  this  is  not  a  part  of  the  testicle,  but  an 
appendage  to  it,  formed  by  the  convolutions  of  its  long  excretory 
duct.  Its  upper  larger  end  is  called  the  globus  major,  and  is 
connected  with  the  testicle  by  the  efferent  ducts ;  the  lower  end, 
globus  minor,  is  only  connected  with  the  testicle  by  fibrous 
tissue  ;  that  part  of  the  epididymis  between  these  two  portions  is 
called  the  body.  A  considerable  quantity  of  unstriped  muscular 
fibre  exists  at  the  posterior  part  of  the  epididymis  and  testig 
beneath  the  infundibuliform  fascia,  and  has  been  described  by 
Kolliker  as  the  inner  muscular  tunic. 


DISSECTION    OP    THE    TESTIS.  66? 

PROPER  Co-  The  coverings  of  the  testicle  are — 1.  A  serous 

VERINOS  OF  THE  membrane,  called  the  tunica  viginalis,  to  facili- 
TESTICLE.  ^ate  its  movements ;  2.  A  strong  fibrous  mem- 

brane, called  the  tunica  albuginea,  to  support  the  glandular 
structure  within ;  3.  A  delicate  stratum  of  minute  blood-vessels, 
which  some  anatomists  have  described  as  a  distinct  coat,  under 
the  name  of  tunica  vasculosa. 

TUNICA  The  tunica  vaginalis  is  a  closed  serous  sac,  one 

VAGINALIS.  part  of  which  (tunica  vaginalis  propria)  adheres 

closely  to  the  testis ;  the  other  (tunica  vaginalis  reflexa)  is  re- 
flected loosely  around  it.  On  opening  the  sac,  it  will  be  seen  that 
the  visceral  layer  completely  covers  the  testicle,  except  behind, 
where  the  vessels  and  duct  are  situated  (fig.  170);  and  that  it 
covers  the  outer  part  of  the  epididymis  in  front  and  behind,  form- 
ing here  a  pouch  called  the  digital  fossa.  The  parietal  layer 
extends  upwards  for  a  variable  distance  upon  the  cord.  The 
interior  of  the  sac  is  smooth  and  polished,  like  all  other  serous 
membranes,  and  lubricated  by  a  little  fluid.  An  excess  of  this 
fluid  gives  rise  to  the  disease  termed  '  hydrocele.' 

The  tunica  vaginalis  was  originally  derived  from  the  perito- 
neum. In  some  subjects  it  still  communicates  with  that  cavity 
by  a  narrow  canal,  and  is  therefore  liable  to  become  the  sac  of  a 
hernia  (see  diagram,  p.  370).  Such  hernise  are  called  congenital 
— a  bad  term,  since  they  do  not  necessarily  take  place  at  birth, 
but  may  occur  at  any  period  of  life,  even  in  very  old  age.*  Some- 
times the  communication  continues  through  a  very  contracted 
canal,  open  to  the  passage  of  fluid  alone ;  or  the  communication 
may  be  only  partially  obliterated,  and  then  one  or  more  isolated 
serous  sacs  are  left  along  the  cord.  Such  an  one,  when  distended 
with  fluid,  gives  rise  to  hydrocele  of  the  cord. 

TUNICA  This  tunic  is  a  dense,  inelastic  membrane,  com- 

ALBUGLNEA.  posed  of  fibrous  tissue,  interlacing  in  every  direc- 

tion ;  analogous  to  the  sclerotic  coat  of  the  eye.     It  completely 

*  It  "would  be  a  better  term  to  call  this  lesion,  a  hernia  in  the  tunica  vaginalis, 
denoting  thereby  its  anatomical  position ;  at  the  same  time  implying  a  congenital 
arrest  in  development,  and  without  limiting  its  occurrence  to  any  age  of  life. 


668  DISSECTION    OF   THE    TESTIS. 

invests  the  testicle,  but  not  the  epididymis.  At  the  posterior  part 
of  the  gland  it  penetrates  into  its  substance  for  a  short  distance, 
and  forms  an  incomplete  vertical  septum,  termed,  after  the 
anatomist  who  first  discovered  it,  corpus  Highmorianum,  and 
subsequently  by  Sir  A.  Cooper,  mediastinum  testis  (fig.  170). 
This  septum  transmits  the  blood-vessels  of  the  organ,  and  contains 
also  the  network  of  seminal  ducts,  called  the  rete  testis,  shown  in 
diagram  (fig.  169). 

From  the  mediastinum  testis  are  given  off,  in  all  directions,  a 
number  of  diverging  slender  fibrous  cords,  which  traverse  the 
interior  of  the  gland,  and  are  attached  to  the  inside  of  the  tunica 


4.  Epididymis. 

1.  Spermatic  artery.  C    Iffi^MSBSBSV    '.        5.  Mediastinum  testis. 

2.  Vas  deferens.  h     ifmjllWBSSL    •        6, 6.  Cavity  of  tunica 

3.  Deferential  artery.  V    1^111X181  F    *  vaginalis. 


TRANSVERSE    SECTION    THROUGH   THE    TESTICLE    (diagrammatic). 

(The  dots  show  the  reflections  of  the  tunica  vaginalis.) 

albuginea.  They  serve  to  maintain  the  general  shape  of  the  testi- 
cle, to  support  the  numerous  lobules  of  which  its  glandular  sub- 
stance is  composed,  and  to  convey  the  blood-vessels  into  it.  These 
septa  (trabeculae  testis)  as  well  as  the  mediastinum  from  which 
they  proceed,  are  readily  seen  on  making  a  transverse  section  through 
the  gland  (fig.  170).* 

TUNICA  Kespecting     the    so-called    tunica    vasculosa 

VASCULOSA.  nothing  more  need  be  said  than  that  it  consists  of  a 
multitude  of  minute  blood-vessels,  formed  by  the  ramifications  of 

*  Kolliker  has  demonstrated  unstriped  muscular  fibres  upon  the  septa  as  well  as 
the  mediastinum. 


DISSECTION    OF    THE.  TESTIS.  669 

the  spermatic  artery,  and  held  together  by  delicate  areolar  tissue. 
It  covers  the  inner  surface  of  the  tunica  albug^iea,  and  gives  off 
branches,  which  run  with  the  fibrous  septa  into  the  interior  of  the 
gland. 

MINUTE  When  the  testis  is  cut  into,  its  interior  looks 

STRUCTURE.  soft    and   pulpy   and    of  a    reddish-grey    colour. 

It  consists  of  a  multitude  of  minute  convoluted  tubes — tubuli 
seminiferi — which  have  each  a  length  of  about  two  feet  and  a 
quarter,  and  a  diameter  averaging  y^-g-  of  an  inch.  For  economy 
of  space  they  are  arranged  in  lobules,  between  three  and  five 
hundred  *  in  number,  of  various  sizes,  and  contained  in  the 
compartments  formed  by  the  fibrous  septa  proceeding  from  the 
mediastinum  testis.  A  few  only  of  these  lobules  are  shown  in  the 
diagram.  Though  disposed  in  lobules,  still  they  communicate 
with  each  other,  and  thus  form  one  large  network  of  tubes.  The 
tubuli  are  lined  with  flattened  cells  of  several  strata  in  thickness, 
resting  upon  a  basement  membrane.  They  commence  either 
by  anastomosing  loops,  or  by  blind  dilated  extremities,  and 
after  pursuing  a  convoluted  course,  unite  into  from  thirty  to 
fifty  straight  vessels  (vasa  recta],  which  penetrate  the  medias- 
tinum testis,  and  there  form  a  plexus  of  seminal  tubes,  termed 
the  rete  testis.  This  lies  along  the  back  of  the  gland.  From  the 
upper  part  of  the  rete,  the  secretion  is  conveyed  to  the  upper 
part  of  the  epididymis  by  twelve  to  fifteen  tubes,  termed  vasa 
efferentia,  which  perforate  the  tunica  albuginea  in  their  course  to 
the  globus  major.  These,  after  forming  a  number  of  coils,  termed 
coni  vasculosi,^  collectively  constitute  the  globus  major  of  the 
epididymis. 

At  the  globus  major  the  smaller  tubes  terminate  in  a  single 
duct — the  canal  of  the  epididymis,  which  in  its  descent  describes 
an  extremely  tortuous  coil,  constituting  the  body  and  globus  minor 
of  the  epididymis.  The  length  of  the  canal  of  the  epididymis  is, 
in  its  natural  condition,  about  three  inches,  but  when  unravelled 

*  The  larger  estimate  is  that  by  Krause;  the  smaller  that  by  Berres. 
f  The  coni  vasculosi  are  about  ^  of  an  inch  in  diameter,  and  about  six  to  eight 
lines  long  ;  when  unravelled  they  attain  a  length  of  six  to  eight  inches. 


670  DISSECTION    OF    THE    TESTIS. 

it  is  nearly  twenty  feet  in  length.  The  diameter  of  the  canal  at  its 
commencement  is  about  -fo  of  an  inch  ;  at  the  globus  minor  about 
JL  of  an  inch,  after  which  it  again  increases  in  diameter.  It  is 
lined  with  columnar  ciliated  epithelium. 

The  vas  defer  ens  begins  at  the  lower  part  of  the 

VAS  DEFERENS 

globus  minor ;  at  first  it  is  somewhat  convoluted, 
but  as  it  ascends  behind  the  epididymis,  it  becomes  subsequently 
straight,  and  joins  the  other  component  parts  of  the  cord.  After 
passing  through  the  inguinal  canal,  it  enters  the  abdomen  through 
the  internal  ring.  It  then  winds  round  the  outer  side  of  the 
epigastric  artery,  and,  after  crossing  over  the  external  iliac  artery 
and  vein,  it  enters  the  pelvis,  curves  round  the  side  and  lower 
part  of  the  bladder,  and  empties  itself  into  the  prostatic  part  of 
the  urethra,  after  running  a  course  of  about  two  feet. 

In  connection  with  the  anterior  aspect  of  the  cord,  just  above 
the  epididymis,  are  two  or  three  small  masses  of  convoluted  tubes, 
which  are  known  as  the  organ  of  Giraldes,  or  the  parepididy- 
mis.  They  are  lined  with  squamous  epithelium,  and  are  probably 
the  remains  of  part  of  the  Woolffian  body. 

The  hydatids  of  Morgagni  are  one  or  two  small  pedun ciliated 
bodies,  situated  between  the  globus  major  and  the  body  of  the 
testis.  They  are  formed  by  pouchings  of  the  tunica  vaginalis, 
and  are  filled  with  blood-vessels  bound  together  by  connective 
tissue.* 

The  vas  aberrans  is  a  small  convoluted  tubule,  with  a  caecal 
extremity,  found  between  the  epididymis  and  the  cord,  and  com- 
municating usually  with  the  canal  of  the  epididymis.  It  is  about 
an  inch  in  length,  but  when  frayed  out  varies  from  two  to  twelve 
inches  in  length.  It,  like  the  organ  of  Giraldes,  is  connected  with 
a  foetal  structure,  the  Woolffian  body. 

SPERMATIC  The  spermatic  cord  is  composed  of  the  spermatic 

CORD,  vessels,    nerves,    and     lymphatics ;    of    the    vas 

deferens,  with   the   deferential  artery  (a  branch   of  the  superior 
vesical) ;  of  the  cremaster  muscle,  and  the  cremasteric  artery,  a 

*  The  largest,  which  lies  upon  the  top  of  the  testis,  is  stated  to  be  the  vestige  of 
]\Iiiller's  duct. 


DISSECTION    OF    THE    TESTIS.  671 

branch  of  the  deep  epigastric.  It  begins  at  the  internal  ring, 
traverses  the  inguinal  canal,  and  extends  to  the  testis,  where  its 
component  parts  pass  to  their  respective  destinations.  The 
coverings  of  the  cord  have  been  described  with  the  anatomy  of  the 
parts  of  hernia  (p.  369). 

The  course  of  the  spermatic  arteries  and  veins  has  been 
described  in  the  dissection  of  the  abdomen/(p.  403).  The  artery 
is  remarkably  tortuous  as  it  descends  along  the  cord ;  it  enters  the 
back  part  of  the  testicle,  and  breaks  up  into  a  number  of  fine 
ramifications,  which  spread  out  on  the  inner  surface  of  the  tunica 
albuginea.  The  spermatic  veins  leave  the  testis  at  its  back  part, 
and,  as  they  ascend  along  the  cord,  become  extremely  tortuous, 
and  form  a  plexus  termed  pampiniform.  It  is  usually  stated  that 
these  veins  are  destitute  of  valves  ;  and  this  fact  is  adduced  as  one 
of  the  reasons  for  the  occurrence  of  varicocele.  It  is,  however, 
certain  that  the  larger  veins  do  contain  valves. 

The  lymphatics  of  the  testis  pass  through  the  lumbar  glands ; 
hence  these  glands,  and  not  the  inguinal,  become  affected  in  malig- 
nant disease  of  the  testis. 

The  nerves  of  the  testicle  are  derived  from  the  sympathetic. 
They  descend  from  the  abdomen  with  the  spermatic  arteries,  and 
come  from  the  aortic  plexus,  with  a  few  filaments  from  the  hypo- 
gastric  plexus,  which  surround  the  deferential  artery  (p.  442). 
This  accounts  for  the  ready  sympathy  of  the  stomach  and  intestine 
with  the  testicle,  and  for  the  constitutional  effects  of  an  injury  to 
it. 

DESCENT  OF  The  testicle  is  originally  developed  in  the  lumbar 

THE  TESTIS.  region,   immediately   below   the   kidney,   and   is 

loosely  attached  to  the  back  of  the  abdomen  by  a  fold  of  peritoneum, 
termed  the  mesorchium,  along  which  its  vessels  and  nerves  run  up 
to  it,  as  to  any  other  abdominal  viscus.  From  the  lower  end  of 
the  gland  a  fibrous  cord,  termed  the  gubernaculum  testis  * 
proceeds  to  the  bottom  of  the  scrotum.  There  is  no  evidence  to 

*  Mr.  Curling  considers  the  gubernaculum  testis  to  be  a  muscular  cord.  See  his 
Observations  on  the  Structure  of  the  Gubernaculum,  and  on  the  Descent  of  the  Testis 
in  the  Foetus:  'Medical  Gazette,'  April  10,  1841. 


672  DISSECTION    OF    THE    TESTIS. 

warrant  the  assumption  that  the  gradual  contraction  of  the 
gubernaculum  effects  the  descent  of  the  testis.  The  organ  begins 
to  descend  from  the  lumbar  region  about  the  fifth  month  of  foetal 
life,  reaches  the  internal  ring  about  the  seventh,  and  about  the 
ninth  has  entered  the  scrotum.  Its  original  peritoneal  coat  is 
retained  throughout ;  but  as  it  enters  the  inguinal  canal,  the 
peritoneal  lining  of  the  abdomen  is  pouched  out  before  it,  and 
eventually  becomes  the  tunica  vaginalis  reflexa.  Immediately 
after  the  descent  of  the  testis,  its  serous  bag  communicates 
with  the  abdomen,  and  in  the  lower  animals  continues  to  do  so 
throughout  life.*  But  in  the  human  subject  the  canal  of  com- 
munication soon  begins  to  close.  It  closes  at  the  upper  extremity 
first,-f-  and  the  closure  is  generally  complete  in  a  child  born  at  its 
full  time4  This  provides  against  the  occurrence  of  ruptures,  to 
which  man,  owing  to  his  erect  position,  is  more  exposed  than 
animals.  At  the  end  of  the  first  month  after  birth,  the  canal  is 
entirely  obliterated  from  the  internal  ring  to  the  testis.  Some- 
times, however,  this  obliteration  fails,  or  is  only  partial ;  hence 
may  arise  congenital  hernia,  or  hydrocele.  The  possible  existence 
of  a  communication  between  the  tunica  vaginalis  and  the  peritoneal 
cavity  of  the  abdomen,  is  one  reason  among  many  why  caution 
should  be  observed  in  treating  hydroceles  in  children  with  stimu- 
lating injections. 

*  According  to  Professor  Owen,  the  African  orang  outang  (Simia  troglodytes}  is 
the  only  exception  to  this  rule.  In  this  animal  it  is  interesting  to  observe  that  the 
lower  extremities  are  more  fully  developed  as  organs  of  support,  and  there  is  a  liga- 
mentum  teres  in  the  hip-joint. 

f  The  frequency  of  hernia  in  the  funicular  portion  of  the  vaginal  process  of  the 
peritoneum  hardly  bears  this  out. 

\  Camper  has  shown,  that  the  canal  on  the  right  side  is  nearly  always  open  at 
birth,  whereas  that  on  the  left  is  usually  closed.  This  explains  the  greater  frequency 
of  hernia  on  the  right  side  in  children  under  one  year  old.  Thus  out  of  3,014  cases 
of  inguinal  hernia  seen  at  the  City  of  London  Truss  Society  under  one  year,  2,269 
occurred  on  the  right  side,  and  745  on  the  left;  or  in  the  proportion  of  3  to  1. 


INDEX. 


ABD 

Abdomen,  parts  exposed  on  opening,  373 

Abdominal  aorta,  relations  of,  401 

Achillis  tendo,  550 

Alimentary  canal,  length  of,  377 

Anser  hypoglossi,  35 

Antrum  pylori,  489 

Aorta,  abdominal,  384,  401 

arch  of,  128 

branches  of,  385 

descending  thoracic,  141 

parts  within  arch,  13d 

relations  of  arch  to  sternum,  130 
Aponeurosis,  lumbar,  234,  313 

of  scalp,  2 

temporal,  96 

vertebral,  234 

Apparatus  ligamentosus  colli,  249 
Appendices  epiploicae,  493 
Appendix  vermiformis,  375 
Aqueduct  of  Sylvius,  612 
Aqueductus  cochleae,  657 

fallopii,  15 

Aqueous  humour,  644 
Arachnoid  membrane  of  brain,  678 
Arbor  vitse,  616 

of  uterus,  471 
Arch,  crural,  357,  504 
deep,  507 

palmar,  superficial,  300 
Arches,  palatine  anterior,  202 
Arciform  fibres  of  medulla,  586 

fibres  of  Eolando,  628 
Arteria  sacra  media,  385,  404 
ABTEEIBS 

alar  thoracic,  263 

anastomotica  magna  of  thigh,  523 
of  arm,  281 

angular,  86 

anterior  auricular,  95 


AET 

AETHEIES  (continued) 

anterior  peroneal,  558 

tibial,  529 

arteria  sigmoidea,  390 
articular  of  popliteal,  544,  552 
auditory,  582 
auricular  anterior,  95 

branch  of  occipital,  55 
posterior,  3,  56 
axillary,  263 
axis,  thoracic,  259 
azygos,  552,  544 
of  the  back,  244 
basilar,  581,  582 
bieipital,  267 

brachial,  course  and  relations,  278 
brachio-cephalic,  130 
bronchial,  151,  176 
buccal,  101 

of  the  bulb  of  urethra,  427 
carotid,  common,  course  of,  32 
internal,  177,  580 

at  base    of    skull, 

227 

course  of,  109 
curves  of,  16 
left,  common,  131 
carpal  of  radial,  anterior,  291 

posterior,  292,  335 
of  ulnar,  anterior,  293 
posterior,  293 
centralis  modioli,  657 

retinae,  214,  644 
cerebellar,  anterior,  582 
inferior,  581 
superior,  582 
cerebral,  anterior,  581 
middle,  581 
posterior,  581,  582 


X  X 


INDEX. 


ART 


ART 


ARTERIES  (continued) 

cervical,  ascending,  67 

deep,  69 
choroid,  anterior,  581 

posterior,  582 
ciliary,  214 

anterior,  215,  639 
long,  215,  639 
short,  215 

circumflex  anterior  of  arm,  267 
posterior  of  arm,  266 
circumflexa  ilii,  deep,  361,  367,  406 
coccygeal,  541 
coeliac  axis,  385,  386 
colic,  middle,  391 

right,  391 
colica  dextra,  390 
media,  390 
sinistra,  390,  392 
comes  nervi  ischiatici,  539,  641 
mediani,  296 
phrenici,  121 

common  iliac,  relations  of,  404 
communicating,  anterior,  581 

posterior,  581 
coronaria  ventriculi,  386 
coronary,  163 

inferior,  86 
superior,  86 
of  corpus  callosum,  581 
cremasteric,  367 
crico-thyroid,  54 
cystic,  386 

of  the  cms  penis,  427 
deep  cervical,  244 
deferential,  442 
descending  palatine,  102 
digital  of  foot,  561 

of  great  toe,  531 
of  hand,  300 

dorsal  of  index  finger,  335 
of  thumb,  335 
of  penis,  427 
dorsalis  hallucis,  531 
linguae,  52 
pedis,  531 
scapulae,  265,  323 
epigastric,  355 
epigastric  deep,  366 

pubic  branch  of,  367 
ethmoidal,  anterior,  215 
posterior,  215 

external  carotid,  course  of,  52 
circumflex,  521 


ARTERIES  (continued?) 

external  iliac,  relations  of,  405 
mammary,  265 
pudic,  355 
pudic,  deep,  497 
facial,  45,  85 
femoral,  518 
frontal,  3,  215 
gastric,  386 
gastro-duodenalis,  386 
gastro-epiploica  dextra,  386 

sinistra,  386 
gluteal,  441,  536 
hsemorrhoidal,  external,  417 
inferior,  417 
superior,  392 
helicine  of  penis,  458 
hepatic,  386 
hyoid,  inferior,  53 
superior,  51 
iliac,  440 
iliac  internal,  440 
ileo-eolic,  391 
ilio-lumbar,  440 
inferior  dental,  100 

external  articular,  552 
internal  articular,  552 
infra-orbital,  93,  102 
spinous,  68,  316 
innominate,  130 
intercostal,  148 

anterior,  121,  149 
collateral,  149 
posterior,  149 
superior,  68 
internal  circumflex,  521 

mammary,  65,  68,  121 
maxillary,  99 
interosseous,  anterior,  296 
common,  293 
dorsal  of  hand,  325 
metatarsal,  531 
palmar,  309 
perforating  of,  309 
posterior,  333 
recurrent,  333 
intra-spinal,  244 
ischiatic,  441,  540 
labial  inferior,  86 
lachrymal,  214 
laryngeal,  superior,  53 
lateral  sacral,  441 
lateralis  nasi,  86 
of  ligamentum  teres,  521,  525 


INDEX. 


675 


ART 


ART 


AETBKIES  (continued) 
lingual,  51 

rule  for  finding,  52 
lumbar,  385,  403 

abdominal  br.  of,  403 
dorsal  branch  of,  403 
spinal  branch  of,  403 
malleolar,  530 
masseteric,  101 
mastoid,  55 
mediastinal,  121 

posterior,  151 
meningea  media,  12 

parva,  12,  100 
meningeal  anterior,  12 

middle,  12,  100 
posterior,  12,  55,  57,  581 
mental,  94 

mesenteric,  inferior,  385,  390,  392 
superior,  385,  390,  391 
metatarsal,  531 
middle  haemorrhoidal,  442 
meningeal,  100 
sacral,  443 
temporal,  95 
vesical,  442 
musculo-phrenic,  121 
mylo-hyoid,  101 
nasal,  102 

branch  of  ophthalmic,  215 
nutrient  of  femur,  522 
of  fibula,  556 
of  humerus  281 
of  tibia,  656 
obturator,  442,  524 
occipital,  3,  55,  244 

auricular  branch  of,  55 
cesophageal,  151 
omentel,  388 
ophthalmic,  214 
ovarian,  475 
palatine,  ascending,  45,  108 

of  ascendi  ng  pharyngeal,  110 
inferior,  45 

palmar  arch,  deep,  309 
palmaris  profunda,  309 
palpebral,  inferior,  215 
superior,  215 
pancreatic,  386 
pancreatica  magna,  388 
pancreatico-duodenal,  inferior,  391 
superior,  386, 

391 
pancreaticse  parvse,  388 


AETEEIES  (contimicd) 

perforating  of  intercostal,  121 
plantar,  561 
profunda,  521 
peroneal,  556 

pharyngeal,  ascending,  56,  110 
phrenic,  385,  402 
plantar,  external,  561 
internal,  561 
popliteal,  544,  551 
posterior  circumflex,  320 
scapular,  316 
tibial,  555 
princeps  cervicis,  55,  244 

pollicis,  308 
profunda  femoris,  520 
inferior,  281 
superior,  279 
pterygo-palatlne,  102 
pterygoid,  101 
pudic,  425,  442,  541 
pulmonary,  151 
pyloric,  386 
radial,  290 

recurrent,  291 
in  palm,  308 
radialis  indicis,  309 
recurrent  tibial,  530 
renal,  385,  402 
sacra  media,  443,  385 
scapular,  posterior,  68 
of  septum,  102 
sigmoidea,  392 
spermatic,  385,  403 
spheno-palatine,  102 
spinal,  anterior,  581,  625 
lateral,  66 
posterior,  581,  625 
splenic,  386,  387 
sterno-mastoid,  inferior,  68 
middle,  54 
superior,  55 
stylo-mastoid,  56,  652 
subclavian,  branches  of,  65 
course  of,  60 
left,  62,  131 

sublingual,  course  of,  52 
submental,  45 
subscapular,  265 
superficial  circumflexa  ilii,  496 
epigastric,  496 
external  pudic,  496 
perineal,  418 
superficialis  colli,  68,  313,  316 


x  x  2 


676 


INDEX. 


ART 


BUR 


ARTERIES  (continued) 

superficialis  volse.  291 
superior  dental,  102 

epigastric,  121 
external  articular,  552 
hsemorrhoidal,  390 
intercostal,  65 
internal  articular,  552 
profunda,  324 
thyroid,  58 
vesical,  441 

supra-aoromial,  68,  315 
orbital,  3,  214 
renal,  385,  402 
scapular,  67,  315,  323 
sural,  544,  553 
tarsal,  631 

temporal  anterior,  95 
deep,  101 

anterior,  101 
posterior,  95,  101 
superficial,  8,  94 
thoracica  acromialis,  259 
alaris,  263 
humeraria,  259 
inferior  or  long,  265 
superior  or  short,  259 
thymic,  121 
thyroid  axis,  65,  67 
inferior,  67 
tonsillar,  45 
transversalis  colli,  68 

faciei,  87.  95 
humeri,  67,  315 

transverse  communicating  of  ankle, 
556 

perineal,  418 
tympanic  of  internal  carotid,  228 

maxillary,  100 
ulnar,  292 

palmar  recurrent  of,  300 
recurrent  anterior,  293 
posterior,  293 
ulnaris  profunda,  300 
uterine,  468 
vaginal,  468 
vasa  brevia,  384,  386 

intestini  tenuis,  391 
vertebral,  65,  66,  581 
vesical,  inferior,  442 
middle,  442 
superior,  441 
vidian,  102 
Aryteno-epiglottic  folds,  193 


Arytenoid  cartilages,  192 
Auricle,  left,  161 

right,  156 
Auriculo  ventricular  opening,  left,  162 

right,  159 
Axilla,  boundaries  of,  262 

contents  of,  261 

dissection  of,  261 

fascia  of,  261 

glands  of,  263 


BACK 

cutaneous  nerves  of,  310 

muscles  of,  234,  310 
Bile-duct,  889 
Bladder,  female,  465 

gall,  480 

ligaments,  false,  of,  429 

lymphatics  of,  449 

peritoneal  covering  of,  412 

positions  of,  413 

urinary,  blood-vessels  of,  449 

urinary,  position  of,  435 
structure  of,  446 
uvula  of,  448 
Bodies,  olivary,  585 

restiform,  586,  627 
Body,  vitreous,  644 
BRAIN 

arteries  of,  380 

convolutions  of,  592 

dissection  of,  578 

fissures  of,  589 

general  description  of,  583 

membranes  of,  578 

peculiarities  of  circulation  in,  583 
Bronchus,  left,  170 

right,  170 

Burn's  falciform,  process  of,  502 
Bursse,  biceps,  near  tendon  of,  346,  276 

of  carpus,  305 

over  knuckles,  325 

over  olecranon,  325 

over  patella,  517 

under    coraco-acromial     ligament, 
341 

under  coraco-brachialis,  277 

under  deltoid,  320 

under  gastrocnemius,  649 

under  gluteus  maximus,  535 
medius,  535 

under  gracilis,  512 

under  latissimus  dorsi,  312 


INDEX. 


677 


BUB 

Bursse,  under  ligamentum  patellae,  51 7 
under  obturator  internus,  537 
under  popliteus,  553 
under  Sartorius,  510 
under  semi-membranosus,  546 
under  subseapularis,  322 
under  teres  major,  322 
under  triceps,  324 
under  tuberosity  of  Ischium,  533 


Caecum,  375 

meso-caecum,  375 
Canal  of  Bowman,  635 

crural,  507 

of  epididymis,  669 

of  Huguier,  227,  650 

of  Hunter,  519 

inguinal,  366 

of  Petit,  646 

of  Recklinhausen,  635 

of  Schlemm,  635 

of  Stilling,  645 

for  tensor  tympani,  651 
Canaliculus  of  eyelid,  80 
Canals  of  cervix  uteri,  471 

reunions,  658 

semicircular,  655 

spiralis  modioli,  657 
Capsule,  Glisson's,  477 
Caput  coli,  375 

gallinaginis,  450 
Cartilages,  tarsal,  80 
Caruncula  lachrymalis,  78 
Carunculse  myrtiformes,  462 
Cauda  equina,  621,  625 
Central  canal  of  spinal  cord,  623 

tendon  of  Perineum,  418 
Cerebellum,  613 

amygdalae  of,  615 

fissure  of,  great  horizontal,  613 

flocculus  of,  615 

lateral  hemispheres  of,  613 

lobes  of,  614,  616 

peduncles  of  inferior,  616 
middle,  616 
superior,  611,  616 

vermiform  process  of,  613 

uvula  of,  615 
Cerebrum,  588 

Chambers  of  eye,  anterior,  638 
posterior,  638 
Chordae  Willisii,  9 
Chordae  tendineae,  158 


COR 

Choroid  coat  of  the  eye,  636 

plexus,  607 

of  the  fourth  ventricle,  612 

plexuses,  579 
Cilia,  78 
Ciliary  muscle,  636,  638 

processes,  636 
Circle  of  Willis,  582 
Clitoris,  459 
Cochlea,  656 
Cceliac  axis,  386 
Colon,  ascending,  375,  383 

commencement  of,  375 

descending,  375,  383 

hepatic  flexure  of,  375 

sigmoid  flexure  of,  376 

splenic  flexure  of,  376 

transverse,  375,  383 

transverse  meso-eolon,  380,  383 
Columnae  corneae,  158 
Columns,  anterior  of  medulla,  626 

lateral  of  medulla,  627 
Commissure,  great  transverse,  600 

anterior,  609 

middle,  609 

optic,  596 

posterior,  610 

of  spinal  cord,  622 
Coni  vasculosi  testis,  669 
Conjunctiva  oculi,  631 
Convolution,  frontal,  592 

occipital,  592 

parietal,  592 

temporo-sphenoidal,  592 

uncinate  or  hippocampal,  593 
Cord  spermatic,  670 
Cornea,  634 

Corneal  tubes  of  Bowman,  635 
Cornicula  laryngis,  190 
Corniculum  laryngis,  192 
Corpora  albicantia,  594 

mammellaria,  594 

quadrigemina,  611 
Corpus  Arantii,  160 

callosum,  589,  600 

cavernosum  penis,  456 

dentatum,  586,  616 

fimbriatum,  606 

geniculatum  externum,  609 
internum,  609 

Highmorianum,  668 

luteum,  475 

spongiosum  penis,  456 

striatum,  606 


678 


INDEX. 


COR 

Corti,  organ  of,  661 

rods  of,  661 

Cotunnii  liquor  or  peri-lymph,  658 
Cowper's  glands,  425,  452 
Cricoid  cartilage,  191 
Cricothyroid  membrane,  191 
Crista  vestibuli,  655 
Crura  cerebri,  structure  of,  628 
Crural  arch,  504 
canal,  507 
Cms  clitoridis,  459 

penis,  456 

Crystalline  lens,  646 
Cuneiform  cartilages,  192 
Cnneus,  593 
Cupola,  657 


Dartos  scroti,  665 

tunica,  417 

Deglutition,  mechanism  of,  188 
Descemet,  membrane  of,  635 
DIAPHRAGM,  395 

aortic  opening  of,  396 

central  tendon  of,  396 

functions  of,  397 

nerves  of,  397 

cesophageal  opening  of,  397 

openings  of,  396 

vena  cava,  opening  of,  397 
Diogenes,  cup  of,  297 
Discus  proligerus,  475 
DISSECTION 

of  the  eye,  631 

of  male  perineum,  414 

of  the  organ  of  hearing,  648 

of  spinal  cord,  617 

of  upper  arm,  27 1 
Duct,  nasal,  231 

thoracic,  142 
DUCTS, 

bile,  389 

cystic,  480 

galactophorus,  664 

of  parotid  gla  ;d,  89 

of  prostate,  451 

of  Rivinus,  50 

of  sublingual  gland,  50 

of  submaxillary  gland,  44 

Wharton's,  44 

DtJCTUS 

anteriosus,  152,  168 

cochlearis,  660 

communis  choledochus,  389,  480 


FAS 

DUCTUS  (continued) 

communis  ejaculatorius,  437 

venosus,  168,  169 
Duodenum,  course  of,  374 

relations  of,  392 
Dura  mater,  6 

sinuses  of,  8 


Ear,  muscles  of,  2 
Elbow,  triangle  at  bend  of,  287 
Endocardium,  165 
Endolymph,  659 
EPIDIDYMIS,  666 

globus  major,  666 
minor,  666 
Epiglottis,  192 

cushion  of,  195 
Eustachian  tube,  186 
Eyelids,  structure  of,  79 


Face,  dissection  of,  73 

Fallopian  tube,  464 
tubes,  473 

fimbrise  of,  473 

Falx  cerebri,  7 
cerebelli,  7 

FASCIA 

cervical,  deep,  21 
iliaca,  399 
of  the  leg,  526 
lumbar,  235 
perineal  deep,  417 
superficial,  417 
plantar,  557 
praevertebral,  22 
propria  of  hernia,  507 

FASCIAE 

anal,  431 
of  the  arm,  275 
of  the  fore-arm,  286 
on  back  of  forearm,  286 
buccal,  85 
cremasteric,  361 
cribriform,  496,  501 
falciform  of  Burns,  502 
infundibuliform,  366 
intercolumnar,  359 
lata  of  thigh,  500 
of  metacarpus,  327 
obturator,  431 
palmar,  297 
pelvic,  430 


INDEX. 


679 


FAS 

FASCIA  (continued) 

pelvic,  in  female,  465 

recto-vesical,  431 

semi-lunar  of  biceps,  276 

spermatic,  359 

superficial  of  abdomen,  354 
thigh,  496 

transversalis,  364 
Fasciculi  teretes,  627 
Faucium  isthmus,  183 
Fenestra  ovalis,  651 

rotunda,  651 

Ferrein,  pyramids  of,  485 
Fibro-cartilages,  between  radius  and  ulna, 
347 

interarticular  of  jaw,  253 

of  clavicle,  339 

inter-vertebral,  247 
Fimbriae  of  the  ovary,  464 
Fissura  palpebrarum,  78 
Fissures,  calcarine  of  brain,  591 

calloso-marginal  of  brain,  591 

of  Bichat,  606 

central  of  brain,  589,  590 

great  transverse,  606 

longitudinal  of  brain,  588 

nerves  in  sphenoidal,  16 

parieto-occipital  of  brain,  589,  591 

primary  of  brain,  589 

of  Sylvius,  588,  590 
Flexor  tendons  in  palm,  sheaths  of,  303 
Foetal  circulation,  168 
Folds,  aryteno- epiglottic,  193 

glosso-epiglottic,  193,  194 
Foramen  chordae  anterius,  654 
posterius,  654 

caecum  of  medulla,  584 

of  Monro,  606 

quadratum,  397 

of  Winslow,  381 
Foramina,  ovale  of  heart,  157,  162 

of  Thebesius,  158 
Fornix,  605 

Fossa  uavicularis  of  urethra,  454 
Fossae,  ischio- rectal,  415,  428 
Fovea  hemispherica,  655 

hemi-elliptica,  655 

centralis,  640 
Frsenum  preputii,  455 


Galen,  rete  mirabile  of,  532 

veins  of,  608 
Gall  bladder,  480 


GLA 

Gall  bladder,  situation  of,  377 
Ganglia,  abdominal  of  sympathetic,  407 

cervical,  inferior,  117 
middle,  116 
superior,  115 

semi-lunar,  385,  395,  407 

of  spinal  nerves,  624 

sympathetic  of  neck,  115 

thoracic  of  sympathetic,  147 
Ganglion  diaphragmaticum,  397 

Gasserian.  13 

impar,  114,  445 

jugular,  224 

of  glosso-pharyngeal,  109 

lenticular,  215 

ophthalmic,  215 

otic,  222 

petrous,  224 

of  glosso-pharyngeal,  109 

of  pneumogastric  of  root,  111 
of  trunk,  112 

of  Eibes,  114 

of  root  of  pneumogastric,  225 

spheno-palatine,  220 

submaxillary,  51,  107 
Gimbernat's  ligament,  50* 
GLANDS  anal,  415 

agminate,  492 

axill  iry,  263 

of  Bartholin,  463 

of  Brunner,  492 

buccal,  85 

Cowper's,  425-,  452 

deep  cervical  lymphatic,  38 

of  Duverney,  463 

lachrymal,  209 

of  Lieberkiihn,  492 

lymphatic,  of  elbow,  275 

superficial  of  neck,  20 
inguinal,  355 

Meibomian,  81 

mesenteric,  390 

molar,  85 

oasophageal,  145 

of  Pacchioni,  9 

palatine,  187 

parotid,  relations  of,  88 

peptic,  490 

of  Peyer,  492 

popliteal,  544 

prostate,  438 

pyloric,  490 

salivary  sublingual,  50 

solitary,  493 


680 


INDEX. 


GLA 

GLANDS  (continued) 

submaxillary,  43 

lymphatic,  45 

superficial  inguinal,  496 

tracheal,  171 

Glandula  socia  parotidis,  88 
Glandulse  concatenate,  39 

Pacchioni,  9 
Glans  clitoridis,  460 
Glisson's  capsule,  389,  477 
Glosso-epiglottic  folds,  193 

pharyngeal  nerre,  598 
Glottidis  rima,  194 
Graafian  resides,  475 
Gubernaculum  testis,  671 
Gyrus  fornicatus,  593 


Hamstring  muscles,  545 
Hamulus  of  cochlea,  657 
Heart,  attachment  of  large  arteries  to,  1 65 

dissection  of,  155 

fibrous  skeleton  of,  164 

form  and  position  of,  134,  137 

nerves  of,  152 

peculiarities  of  feetal,  167 

position  and  form  of,  134 

thickness  of  its  cavities,  166 
Heart  valves,  position  of,  138 
Helicotrema,  657 

Henle,  looped  tubes  of,  in  kidney,  486 
Hernia,  congenital,  370 

direct  inguinal,  369 

encysted,  371 

funicular,  371 

femoral,  anatomy  of  parts  concerned, 
503 

coverings  of,  508 

seat  of  stricture  in,  509 

division  of  stricture  in,  509 

infantile,  371 

inguinal,  direct,  369 

oblique  inguinal,  368 

position  of  spermatic  cord  in,  371 

seat  of  stricture  in,  371 
Herophili  torcular,  11 
Hessel bach's  triangle,  369 
Hey's  ligament,  503 
Hippocampus  major,  604,  607 
minor,  603,  607 
Houston,  valves  of,  495 
Huguier,  canal  of,  650 
Humour,  aqueous,  644 
vitreous,  644 


J01 

Hunter's  canal,  519 
Hyaloid  membrane,  644 
Hydatids  of  Morgagni,  671 
Hymen,  462 
Hypoglossal  nerve,  599 


Ileo-csecal  valve,  495 

Ileum,  374 

Incus,  652 

Infundibulnm  of  right  ventricle,  159 

Interarticular  fibro-cartilage  of  knee,  570 

Internal  ear,  654 

Intestine,  large,  375 

external  characters  of,  493 
small,  374 

glands  of,  492 
lymphatics  of,  493 
nerves  of,  493 
structure  of,  490 
Iris,  638 

arteries  of,  639 
muscular  fibres  of,  639 
nerves  of,  639 
Ischio- rectal  fossa,  428 
Iter  a   tertio  ad   quartum  ventriculam, 
609,  612 


Jacob's  membrane,  643 
Jejunum,  374 
Joints,  ankle,  572  r 

between  atlas  and  axis,  250 

of  carpns,  348 

costo-sternal,  252 

crico-arytenoid,  192 
thyroid,  201 

elbow,  343 

of  the  fingers,  351 

of  the  foot,  574 

hip,  566 

intr-rcarpal,  349 

knee,  568 

carpo-metacarpal,  350 

lower  jaw,  252 

occipito-atlantoid,  249 

radio-carpal  of  wrist,  346 

radio-ulnar,  inferior,  346 
superior,  345 
ribs  of  the,  251 

scapulo-clavicular,  340 

shoulder,  341 

sterno-clavieular,  338 

tarsal,  5H 


INDEX. 


681 


JOI 

Joints,  tarso-metatarsal,  576 
of  the  thumb,  349 
tibio-fibular,  superior,  572 
inferior,  572 
of  the  toes,  577 
wrist,  synovial  membrane  of,  351 


Kidneys,  relations  of,  394 
situation  of,  378 
structure  of,  483 


Labia  majora,  459 

minora,  459,  460 
Labyrinth  of  internal  ear,  654 
Lachrymal  gland,  209 

sac,  231 

Lacunae  of  urethra,  454 
Lamina  cinerea,  594 
cribrosa,  633 
fusca,  633 

spiralis  of  cochlea,  657 
Lancisi,  nerves  of,  601 
Laryngotomy,  40 
Larynx,  cartilages  of,  189 
dissection  of,  189 
mucous  membrane  of,  193 
muscles  of,  197 
nerves  of,  200 
opening  of  inferior,  194 
superior,  194 
sacculus  of,  195,  196 
ventricle  of,  195,  196 
vessels  of,  199 

Lawrence,  on  femoral  hernia,  507 
Lens,  crystalline,  646 
LIGAMENTS,  alaria,  570 
of  ankle  anterior,  573 
posterior,  573 

annular  anterior  of  ankle,  527 
external  do.,  527 
internal  do.,  527 
of  carpus  anterior,  301 
of  radius,  345 
posterior  of  wrist,  326 
anterior  of  carpus,  348 
elbow,  345 
wrist,  346 

astragalo-calcaneal,  574 
scaphoid,  574 

atlanto-axoid  anterior,  250 
posterior,  250 
broad  tarsal,  80 


LIG 


LIGAMENTS  (continued?) 
broad  of  uterus,  463 
calcaneo-cuboid  inferior,  575 
superior,  575 
scaphoid,  575 

of  carpus  lateral  external,  348 
internal,  348 
interosseous,  348 
conoid,  340 
coraco-acromial,  341 
clavicular,  340 
humeral  or  accessory,  342 
coronary  of  knee,  571 
costo-clavicular  or  rhomboid,  339 
sternal,  252 
transverse  anterior,  251 
middle,  251 
posterior,  251 
vertebral  or  stellate,  251 
cotyloid,  568 
crico-thyroid,  191 
crucial,  570 
denticulate,  620 
external,  575 

lateral  of  elbow,  344 
of  jaw,  252 
of  wrist,  346 
tarsal,  80 

glenoid  of  shoulder,  343 
glosso-epiglottic,  202 
great  sacro-ischiatic,  566 
Gimbernat's,  359,  504 
Hey's,  503 
of  hip  joint,  566 
hyo-epiglottic,  193 
ilio-femoral,  568 
lumbar,  565 

interarticular  of  rib,  251 
intercarpal,  349 
inter-clavicular,  338 
internal  lateral  of  elbow,  344 
annular  of  ankle,  555 
lateral  of  jaw,  252 
of  wrist,  346 

interosseous  of  fore-arm,  345 
of  leg,  572 
of  metacarpus,  350 
of  tarsus,  576 
interspinous,  246 
of  jaw,  internal  lateral,  107 
of  knee  joint,  568 
lateral  of  ankle,  external,  572 
internal,  572 
external  of  knee,  569 


682 


INDEX. 


LIG 

LIGAMENTS  (continued) 

lateral  internal  of  knee,  569 
latum  pulmonis,  139 
lesser  sacro-ischiatic,  566 
of  the  liver,  377,  477 
mucosum  of  knee,  570 
nuchae,  234,  248,  311 
occipito-atlantoid  anterior,  249 

posterior,  249 
axoid,  249 

oblique  of  radius,  345 
odontoid  or  check,  249 
orbicular  of  radius,  345 
of  the  ovary,  463,  474 
pa1  mar  of  fingers,  304,  352 
palpebral,  80 
of  patella,  516 
of  the  pelvis,  564 
plantse  breve,  575 

longum,  575 

posticum  Winslowii,  546,  569 
posterior  of  carpus,  348 
of  elbow,  345 
of  wrist,  346 
Poupart's,  357,  504 
pterygo-maxillary,  84,  180 
pubic  anterior,  365 
posterior,  365 
round  of  uterus,  464 
sacro-iliac,  anterior,  565 

interosseous,  566 
oblique,  566 
posterior,  565 
ischiatic,  great,  566 

less,  566 
spinal  anterior  common,  246 

posterior  common,  246 
of  the  spine,  246 
stellate,  251 

sterno-clavicular  anterior,  338 
posterior,  338 
stylo-hyoid,  108 
stylomaxillary,  23,  46 
snbflava,  246 
sub-pubic,  365 
supra-spinous,  246 
suspensorium  penis,  456 
teres,  567 

of  liver,  372 
thyro-epiglottic,  193 

hyoid  anterior,  1 90 

lateral,  190 

tibio-fibular  anterior,  571 
posterior,  571 


LYM 

LIGAMENTS  (continued) 

transverse  of  atlas,  250 
fingers,  298 
knee,  571 
metacarpal,  336 
metatarsal,  577 

trapezoid,  340 

triangular  of  urethra,  417,  422,  424 

of  tympanic  bones,  653 

Winslowii  posticum,  569 

LlGAMENTUM 

arcuritum  extern um,  396 
internum,  396 

spirale,  661 

suspensorium,  250 

Ligature  of  external  iliac  artery,  406 
LINEA 

alba,  357,  363 

semi-lunaris,  363 

splendens,  620 

transversa,  362 

Listen,  ligature  of  external  iliac,  497 
Lithotomy,  415 

parts  divided  in,  424 
LIVEB 

description  of,  475 

fissures  of,  476 

functions  of,  480 

ligaments  of,  377,  477 

lobes  of,  476 

lobules  of,  478 

lymphatics  of,  480 

nerves  of,  480 

position,  377 

Lobes  of  brain,  central,  591 
frontal,  591 
parietal,  591 
occipital,  591 
temporo-sphenoidal,  591 
Lobulus  Spigelii,  476 
Locus  niger,  629 

perforatus  anticus,  594 
posticus,  594 
Lower,  tubercle  of,  158 
Lung,  constituents  of  root,  153 
Lungs,  lobules  of,  174 

lymphatics  of,  176 

nerves  of,  176 

position  of,  124 

position  and  form  of,  140 

structure  of,  169,  172 
Lymphatic  glands,  bronchial,  152 

intercostal,  151 
Lymphatics  in  lumbar  region,  401 


INDEX. 


683 


LTM 

Lymphatics  of  small  intestine,  493 

oftestis,  671 
Lyra,  6C6 


Macula  lutea,  640 

Malleus,  652 

Malpighi,  capsules  of,  484 

pyramids  of,  484 
Malpighian,     corpuscles     of    spleen, 

482 
Mammary  gland,  663 

arteries  of,  664 

lymphatics  of,  664 

structure  of,  663 
Mammilla,  664 
Masticntion,  muscles  of,  94 
Meatus  auditorius  externus,  649 

urinarius,  female,  460 
MEDIASTINUM 

anterior,  122 

middle,  122 

posterior,  122,  141 

testis,  668 
Medulla  oblongata,  583 

minute  structure   of,  626 
Membrana  pupillaris,  640 

tectoria,  661 

tympani,  651 

arteries  of,  652 
Membrane,  basilar,  660 

costo-coracoid,  258 

hyaloid,  644 

of  Reissner,  660 
Membraneous  labyrinth,  657 

semicircular  canals,  658 
Mesentery,  382 
Mesorchium,  672 
Modiolus  of  cochlea,  657 
Monro,  foramen  of,  606 
Morgagni,  hydatids  of,  671 

sinus  of,  180 

Miiller,  fibres  of,  642 
MUSCLES 

abdominal,  functions  of,  363 
nerves  of,  364 

abductor  indicis,  337 

minimi  digit!  manus,  307 

pedis,  558 
pollicis  manus,  306 
pedis,  585 

accelerator  urinse,  420 

accessorius  ad  sacro-lumbalem,  236 
flexor,  560 


MUS 

MUSCLES  (continued) 

adductor  brevis  femoris,  513 
longus,  512 

magnus,  514 
pollicis  manus,  307 

pedis,  562 
anconeus,  330 
aryteno-epiglottideus,  198 
arytenoideus,  198 
attoilens  aurem,  2 
attrahens  aurem,  2 
azygos  uvulae,  184,  185 
biceps  of  arm,  276 
brachialis  anticus,  278 
buccinator,  83 
cervicalis  ascendens,  236 
ciliaris,  77 
ciliary,  636,  638 
coccygeus,  439 
cochlearis,  661 
complexus,  238 
compressor  naris,  82 

sacculi  laryngis,  196 
urethrae,  425 

in  the  female,  461 
coraco- brachialis,  277 
corrugator  supercilii,  77 
creenaster,  361 

crico-arytenoideus  lateralis,  198 
posticus;  197 
crico-thyroideus,  197 
crurseus,  516 
deltoid,  318 
depressor  alse  nasi,  82 

anguli  oris,  75 
labii  inferioris,  75 
digastricus,  41 
dilatator  iridis,  639 

naris  anterior,  82 
posterior.  82 
ejaculator  urinae  42 ) 
erector  clitoridis,  459 
penis,  420 
spinae,  236 

external  sphincter  ani,  416 
extensor  brevis  digitorum,  530 

carpi  radialis  brevior,  328 
longior,  328 
carpi  ulnaris,  330 
communis  digitorum,  329 
indicis,  332 
longus  digitorum,  628 
minimi  digiti,  330 
ossis  met.  pollicis,  331 


684 


INDEX. 


MUS 

MUSCXKS  (continued) 

extensor  primi  internodiipollicis,331 
secundi  internodii  pollicis, 

332 

proprius  pollicis,  529 
flexor  accessorius,  560 

brevis  digitorum,  559 

minimi  digiti  manus,308 
pedis,  563 
pollicis  manus,  307 

pedis,  562 
carpi  radialis,  288 
ulnaris,  288 
flexor  cruris,  545 

longus  digitorum,  554 
pollicia,  554 

manus,  295,305 
profundus  digitorum,  295 
gastrocnemius,  549 
gemellus  inferior,  537 
superior,  537 
genio-hyoglossus,  "48 

hyoideus,  47 
gluteus  maximus,  534 
medius,  535 
minimus,  535 
gracilis,  512 
hyoglossus,  47 
iliacus,  399 

inferior  constrictor  of  pharynx,  178 
infra-spinatus,  321 
intercostal,  148 
interosseous  of  foot,  563 

of  hand,  336 
interspinales,  240 
intertransversales,  240 
ischio-cavernous,  421 
latissimus  dorsi,  270,  312 
laxator  tympani,  653 
levator  anguli  oris,  83 

scapulae,  314 
ani,  439 

female,  465 
labii  inferioris,  75 

superioris  alaeque  nasi, 
83 

proprius,  83 
menti,  75 
palati,  185 
palpebrse,  79,  210 
prostatse,  439 
levatores  costarum,  240 
linguales,  inferior,  205 
superior,  205 


MUS 

MUSCLES  (continued) 

longissimus  dorsi,  236 
longus  colli,  245 
lumbricales,  manus,  306 

pedis,  560 
masseter,  96 
of  mastication,  94 

middle  constrictor  of  pharynx,  179 
mucosse,  491 
multifidus  spinse,  239 
muscularis  mucosse,  491 
mylo-hyoideus,  46 
obliquus  externus  abdominis,  357 
inferior,  216 

capitis,  241 

internus  abdominis,  359 
superior,  211 

capitis,  241 

obturator  externus,  538 
internus,  537 
occipito-frontalis,  2 
opgonens  digiti  minoris,  308 

pollicis,  307 
orbicularis  oris,  74 

palpebrarum,  76 
omo-hyoid,  29,  315 
palato-glossus,  184,  185 
pharyngeus,  185 
palmaris  brevis,  297 
pectineus,  513 
pectoralis  major,  256 
minor,  263 
perineus  brevis,  532 

longus,  531,  564 
tertius,  528 
plantaris,  550 
platysma  myoides,  17 
palmaris  longus,  288 
popliteus,  553 
prsevertebral,  244 
pronator  quadratus,  296 
radii  teres,  288 
psoas  magnus,  398 
parvus,  399 

pterygoidtus  externus,  98 
internus,  99 
pyramidalis,  363 

nasi,  2,  82 
pyriformis,  537 
quadratus  femoris,  537 

lumborum,  400 
quadriceps  femoris,  515 
recti  of  the  eye,  211 
rectus  abdominis,  362 


INDEX. 


685 


MUS 

MUSCLES  (continued) 

rectus  capitis  anticus  major,  245 
minor,  245 
lateralis,  242 
posticus  major,  240 
minor,  240 
externus  oculi,  211 
femoris,  515 
internus  oculi,  211 
inferior  oculi,  211 
superior  oculi,  211 
retrahens  aurem,  3 
risorius,  17,  74 
rotatores  spinae,  239 
rhomboideus  major,  314 
minor,  314 
sacro-lumbalis,  236 
Sartorius,  510 
scalenus  anticus,  58 
medius,  58 
posticus,  58 
semi-membranosus,  546 
semi-spinalis  colli,  239 
dorsi,  239 

semi-tendinosus,  546 
Berratus  magnus,  270,  316 

posticus  inferior,  234 
superior,  234 
soleus,  550 

sphincter  ani  internus,  494 
iridis,  639 
vaginae,  462 
vesicae,  446 
spinalis  dorsi,  238 
splenius  capitis,  235 

colli,  235 
stapedius,  654 
sterno-cleido-mastoideus,  '24 
hyoid,  29 
thyroid,  29 
stylo-glossus,  49,  107 
hyoideus,  43 
pharyngeus,  108 
eubanconeus,  324 
subclavius,  258 
subcrurseus,  516 
Bublimis  digitorum,  289 
subscapularis,  270,  322 
superior  constrictor  of  pharynx,  180 
supinator  radii  brevis,  332 
longus,  29  0 
supra-spinatus,  322 
temporal,  97 
tensor  fasciae  femoris,  514 


NER 

MUSCLES  (continued) 
tensor  palati,  185 
tarsi,  217 
tympani,  653 
teres  major,  270,  322 

minor,  321 
thyro-arytenoideus,  199 

hyoid,  31 
tibialis  anticus,  527 

posticus,  554,  564 
trachelo-mastoid,  237 
trans versalis  abdominis,  361 
colli,  237 
pedis,  563 

transverso-spinalis,  238 
transversus  perinei,  421 

deep,  422 
trapezius,  311 
triangularis  sterni,  120 
triceps  extensor  cubiti,  284,  323 

femorie,  515 
of  ureters,  449 
vastus  externus,  516 
internus,  516 
zygomaticus  major,  76 
minor,  76 

Musculi  papillares,  158 
pectinati,  156,  161 


Nabothi  ovula,  471 

Nasal  fossae,  posterior  openings,  182 

Neck,  central  line  of,  39 

dissection  of,  17 
NEBVES 

abducens  oculi,  15 
accessory  obturator,  410 
anterior  crural,  410,  523 

cutaneous  of  abdomen,  356 
tibial,  532 
auditory,  15 
auriculo-parotidean,  20 

temporal,  5,  95,  165 
auricular  branch  of  pneumogastric, 
112,  225 

posterior,  56 
axillary,  plexus  of,  267 
back,  cutaneous  of,  310 
buccal  branch  of  facial,  92 

of  inferior  maxillary,  104 
calcaneo-plantar,  557 
cardiac  branch  of  pneumogastric,  113, 
146 

inferior,  117 


686 


INDEX. 


NER 

NERVES  (continued) 

cardiac  middle,  116 
superior,  116 

carotid  of  glosso-pharyngeal,  109 
cervical,  acromial  branch  of,  21 
clavicular,   branch  of,  21 
first,  228 
second,  228 
sternal,  branch  of,  21 
superficial,  21 
cervico-facial,  91 
chorda  tympani,  107,  227,  654 
ciliary,  640 

long,  213 

circumflex,  269,  320 
coccygeal,  244,  444 
communicans  Peronei,  542 
commnnicans  noni,  35,  57 
cranial,  exit  of,  1 2 

at  base  of  skull,  224 
crural  branch  of  genito-crural, 

410,  500 

cutaneous  of  neck,  20 
thigh,  499 

external,  4 
internal,  499 
middle,  49 
dental,  anterior,  219 
posterior,  219 
descendens  noni,  35 
dorsal  branch  of  ulnar,  326 
eighth  pair,  15 

origin  of,  598 
external  cutaneous  of  leg,  532 

of  musculo-spiral, 

272 

of  peroneal,  526 
of  thigh,  410 
laryngeal,  200 
respiratory,  72 

of  Bell,  271 
facial,  15,  90 

cervical  branch  of,  21 
in  temporal  bone,  226 
fifth  pair,  13 

origin  of,  579 
first  pair,  13 

lumbar,  408 
fourth  cranial,  209 

pair,  origin  of,  597 
(patheticus),  13 
frontal,  208 

genital  branch  of  genito-crural,  410 
genito-crural,  356,  409,  500 


KEE 

NEBYES  (continued') 

gluteal,  external,  540 
inferior,  540 
superior,  445,  536 
glosso-pharyngeal,  15,  108,  206 
great  ischiatic,  538 

occipital,  5,  310 
gustatory.  50,  106 
hypoglossal,  15,  49,  114 
ilio-hypogastric,  356,  409 

inguinal,  356,  409,  500 
incisor,  106 
inferior  dental,  106 

laryngeal  or  recurrent,  145 
maxillary,  103 
infra-maxillary  of  facial,  92 
orbital  of  facial,  92 

of  superior  maxillary,  93 
trochlear,  93,  214 
intercostal,  150 

cutaneous  branches,  150, 

256 

humeral,  262 
lateral  cutaneous  of,  262 
internal  cutaneous  of  arm,  271 
interosseous  anterior,  295,  296 

posterior,  285,  325,  333 
ischiatic,  548 

great,  538,  542 
lesser,  445,  544 

Jacobson's  or  tympanic,  224,  225 
lachrymal  209 
laryngeal,  external,  55,  112 
inferior,  113 

inferior  or  recurrent,  200 
internal,  112 
recurrent,  113 
superior,  54,  112,  200 
lateral  cutaneous  of  abdomen,  356 
lesser  cutaneous  of  arm.  272 
ischiatic,  445,  539 
musculo-spiral,  272 
lingual,  50 

of  glosso-pharyngeal,  109 
long  or  inferior  pudendal,  540 
long  saphenous,  523 
lumbar,  plexus  of,  408 

sympathetic,  407 
lumbo-sacral,  444 

tympanic,  224,  225 
malar  branch  of  superior  maxillary, 

217 

malar  of  facial,  92 
median,  282,  294 


INDEX. 


687 


NEE 


NER 


NKEVES  (continued) 

median  in  the  palm,  302 
mental,  94,  106 
masseteric,  104 
motor  oculi,  597 
motores  oculi,  13 
musculo-cutaneous,  283 

spiral,  284 
mylo-hyoid,  106 

hyoidean,  45 
obturator,  410,  524 
ccsipital,  small,  21 
olfactory,  13,  233,  596 
optic,  13,  214 

origin  of,  596 
orbital  branch  of  superior  maxillary, 

217 

nasal,  213 
naso-lobular,  82,  93 
nervi  molles,  87 
nervus  accessorius,  26 
ninth  pair,  15 

origin  of,  599 
palatine  anterior,  221 
external,  221 
nasal  branches  of,  221 
smaller,  221 
naso,  221 
palmar  branch  of  median,  297 

of  ulna,  297 

cutaneous  of  median,  295 
peroneal,  539,  542, 

superficial,  419 
pes  anserinus,  91 
petrosal,  external,  227 
great,  221,  226 
lesser,  222 
pharyngeal,  221 

of  pneumo-gastric,  112 
phrenic,  57,  59 

in  chest,  132 
plantar,  external,  562 
internal,  562 
pneumo-gastric,  15,  225 

in  the  chest,  145 
course  of,  110 
popliteal,  internal,  543 
portio  dura,  90 
posterior  auricular,  5,  91 

branches  of  spinal,  242 
tibial,  556 
thoracic,  72,  271 

pudendal,    inferior     or    long,    417, 
419 


NEBVES  (continued) 
pndic,  427,  445 
pulmonary  branches  of  pneumo-gaa- 

tric,  146 

radial,  285,  292,  325 
recurrent  or  inferior  laryngeal,  145 
rhomboid,  315 
sacral,  443 

fourth,  417 
saphenous,  long,  523,  525 

short,  549 
second  pair,  13 

origin  of,  596 
seventh  pair,  15 

origin  of,  598 
short  saphenous,  543,  549 
shoulder,  cutaneous  of,  317 
sixth  cranial,  216 
pair,  15 
origin  of,  598 
small  occipital,  5 
in  sphenoidal  fissure,  16 
spinal,  623 

accessory,  15,  113,  314 
origin  of,  623 
posterior  branches  of,  242 
splanchnic,  great,  147 
lesser,  147 
smallest,  147 
suboccipital,  228 
subscapular,  269 
superior  gluteal,  445 

maxillary,  218 
supra-clavicular,  255 

maxillary  branch  of  facial,  92 
orbital,  4,  93,  209 
scapular,  72,  316,  323 
trochlear,  4,  93,  208 
sympathetic,  cervical,  114 

in  the  chest,  147 
in  the  pelvis,  445 

temporal  branch  of  superior  max- 
illary, 5,  217 
deep,  104 

anterior,  104 
posterior,  104 
temporo-facial,  5,  91 

malar,  94 
third  cranial,  216 
nerve,  13 

pair,  origin  of,  597 
thoracic  anterior,  260 
tonsillar  of  glosso-pharyngeal,  1 09 
trifacial,  13 


688 


INDEX. 


NEB 

NEBVES  (continued) 

trigeminal,  origin  of,  597 

trochlear,  597 

ulnar,  283,  294 

deep  palmar  branch  of,  309 
dorsal,  cutaneous  of,  294 
in  the  palm,  301 

vestibular,  659 

vidian,  221,  222 

Nervi  molles,  87,  116 

Nervus  accessorius,  599 
NOSE 

arteries  of,  232 

cartilages  of,  228 

dissection  of,  228 

infundibulum  of,  230 

interior  of,  229 

meatus  of,  230 

mucous  membrane  of,  231 

nerves  of,  233 

septum  of,  229 

reins  of,  233 

(Esophagus,  143 

Olfactory  nerve,  origin  of,  596 

sulcus,  595 
Olivary  bodies,  585 

nucleus,  586 
Omentum 

gastro-hepatic,  380,  383 
splenic,  378,  384 

great,  380 

lesser,  383 
Optic  nerve,  596 
OBBIT 

contents  of,  208 

dissection  of,  206 

fascia  of,  207 

periosteum  of,  207 
Organ  of  Corti,  661 

of  Giraldes,  671 

of  hearing,  dissection  of,  648 
Os  cordis,  165 
hyoides,  189 
orbiculare,  653 
uteri,  468 

Ossicula  auditus,  652 
Otoconia  or  otoliths,  658 
Ovaries,  situation  of,  474 
Oviducts,  473 


Pacini,  corpuscles  of,  303,  459 


PIN 
PAZ.ATB 

arches  of,  184 
hard,  187 
soft,  183 
muscles  of,  184 

Palm  of  the  hand,  dissection  of,  297 
Pancreas,  relations  of,  393 

situation  of,  878 
Pauniculus  carnosus,  18 
Papilla  lachrymalis,  78 
Parotid  gland,  88 

structures  within,  89 
Patella,  ligament  of,  516 
Pelvic  fascia  in  female,  465 

viscera,  general  position  of  in  male. 
431 

side  view  of,  429 
PELVIS 

contents  of  male,  412 
dissection  of,  411 
functions  of,  411 
male  and  female,  411 
side  view  of  female,  465 
PENIS 

glans,  455 
lymphatics  of,  459 
structure  of,  455 
Peptic  cells,  490 
glands,  490 
Pericardium,  134 

vestigial  fold  of,  137 
Peri-lymph,  or  liquor  Cotunnii,  658 
PERINEUM 

anal  division,  414 
central  tendon  of,  418 
in  the  female,  459 
male,  414 

urethral  division,  414 
Peritoneum,  course  of,  379 
greater  cavity  of,  381 
lesser  cavity  of,  381 
Pes  accessorius,  603 
anserinus,  74 
hippocampi,  604 
Petit,  canal  of,  646 
PHARYNX, 

aponeurosis  of,  178,  180 
dissection  of,  177 
fascia  of,  178 
muscles  of,  178 
openings  into,  182 
Pia  mater  of  brain,  579 
Pineal  body,  610 
Pinna  of  the  ear,  648 


INDEX. 


689 


PIN 

Pinna  of  the  ear,  arteries  of,  649 

cartilage  of,  648 

ligaments  of,  648 

muscles  of,  648 

nerves  of,  649 

Pituitary  body  or  gland,  594 
Platysma,  17 
Pleura,  139 
PLEXUS  OF  NERVES 

Auerbach's,  493 

cervical,  57 

inferior  haemorrhoidal,  445 

Meissner's,  493 

mesenteric,  or  Auerbaeh's,  493 

cesophageal,  146 

patellar,  525 

prostatic,  445 

renal,  487 

sacral,  444 

superior  mesenteric,  493 
uterine,  445,  468 
vaginal,  445,  466,  468 
PLEXUSES 

axillary,  267 

brachial,  70,  267 

'anterior,  111 

cardiac,  153 

carotid,  115 

cavernous,  116 

coronary,  153 

hypogastric,  408 

infraorbital,  92 

lumbar,  408 

posterior,  111 

pharyngeal,  109 

pterygoid  of  veins,  87 

pulmonary  anterior,  146 
posterior,  146 

solar,  385,  407 

of  veins,  pterygoid,  103 
Plica  semilunaris,  78 
Pomuni  Adami,  190 
Pons  hepatis,  477 

varolii,  587 

minute  structure  of,  62 13 
Popliteal  space,  boundaries  of,  541 
Portio  dura,  598 

mollis,  598 
Porus  opticus,  640 
Poupart's  ligament,  504 
Preputium  clitoridis,  460 
Process,  vermiform  inferior,  613 

superior,  613 
Processes,  ciliary,  636 


SAC 

Processus  a  cerebello  ad  cerebrum,  611 

clavatus,  586 
Prsecuneus,  593 
Prostate,  450 

calculi  of,  451 
ducts  of,  451 
gland,  position  of,  438 
relations  of,  438 
Promontory  of  tympanum,  651 
Pubic  symphysis,  565 
Puncta  lachrymalia,  80 
j  Punctum  lachrymale,  78 
Pylorus,  glands  of,  490 

sphincter  of,  489 

Pyramids,  anterior  of  medulla,  58t 
posterior,  628 

of  medulla,  586 
of  tympanum,  651 


Ranula,  44 

Keceptaculum  chyli,  142,  39  J 

Rectum,  376 

Rectum,  arteries  of,  434 

course  of,  412 

digital,  examination  of,  434 

folds  of  mucous  membrane  in,  49.) 

relations  of,  432 

structure  of,  494 
Reil,  fillet  of,  627 

island  of,  591 
Recto-vaginal  pouch,  465 

vesical  pouch,  412 
Region,  infra-clavicular,  258 

prsecordial,  125,  137 

pterygo-raaxillary,  94 

submaxillary,  41 

temporal,  94 

Renal  capsules,  situation  of,  379 
Respiration,  397 
Rete  mirabile  of  Galen,  582 

testis,  668 
Retina,  640 

arteries  of,  644 

minute  structure  of,  642 
Rima  glottidis,  194 
Ring,  crural  or  femoral,  505,  507 

external  abdominal,  358 

internal  abdominal,  365 
Rolando,  arciform  fibres  of,  586 
Ruysch,  tunic  of,  637 


Saccule  of  labyrinth,  658 


Y  Y 


(590 


INDEX. 


SAC 


TON 


Sacro-iliac  symphysis,  565 

baphenous,  opening  of  fascia  lata,  499,  501 

Scala  tympani,  657 

vestibuli,  657 
Scalp,  arteries  of,  3 

dissection  of,  1 

lymphatics  of,  6 

nerves  of,  4 
strata  composing,  1 

surgical  interest  of,  5 

veins  of,  3 

Scarpa's  triangle,  510 
Sclerotic  coat  of  eye,  632 
Scrotum,  dissection  of,  665 
Semi-lunar  cartilages  of  knee,  570 
Septa,  external  intermuscular  of  arm,  275 

internal  intermuscular  of  arm,  275 
Septum,  intermuscular  of  thigh,  501 

lucidum,  604 

scroti,  665 

pectintforme,  456 

Sheath,    for  extensor  tendons    of   wrist, 
327 

of  femoral  vessels,  506 
Sheaths,  of  the  rectus  abdominis,  362 
Sigmoid  flexure  of  colon,  376 
SINUSES 

cavernous,  10,  15 

circular,  10 

coronary,  163 

inferior  longitudinal,  10 
petrosal,  10 

lateral,  9 

of  Morgagni,  180 

occipital,  11 

of  prostate,  450 

straight,  10 

superior  longitudinal,  8 
petrosal,  10 

transverse,  11 

of  Valsalva,  129,  161,  162 
Solar  plexus,  407 
Sole  of  the  foot,  557 
Spaces,  interpleural,  122 
Spermatic  cord,  670 
Spigelii  lobulus,  476 
SPINAX  CORD 

arachnoid  of,  619 

arteries  of,  625 

central  canal  of,  623 

cerebro-spinal  fluid  of,  618 

commissures  of,  622 

columns  of,  622 

dissection  of,  617 


SPINAL  CORD  (continued') 

dura  mater  of,  618 

filum  terminate  of,  620 

fissures  of,  621 

functions  of,  62G 

ligamentum  denticulatum  of.  620 

membranes  of,  618 

pia  mater  of,  6'-'0 

veins  of,  618 

Spine,  movements  of  the,  248 
Spleen,  situation  of,  378 

suspensory  ligament  of,  378 

structure  of,  48 1 
Stapes,  653 
Steno's  duct,  89 
Stomach,  position  of,  373 

structure  of.  488 
Sub -arachnoid  fluid,  579 
Subdural  space,  6 

Supra-renal  capsules,  structure  of.  487 
Sylvius,  fissure  of,  588 
Sympathetic,  in  the  penis,  446 
Symphysis,  pubic,  565 

sacro-iliac,  565 


T<enia  Hippocampi,  606 

semi-circularis,  607 
Tarsal  cartilages,  80 
Tegmentum,  629 
Tendo  Achillis,  550 

oculi,  76 

palpebrarum,  76 

Tendon,  central  of  diaphragm.  396 
Testis,  dissection  of,  667 

descent  of,  672 

gubernaculum  of,  672 
Tentorium  cerebelli,  7 
Thalamus  opticus,  608 
Thebesii  valvula,  158,  164 

foramina,  158 

Theca  of  flexor  tendons  in  palm,  303 
Thoracic  duct,  1 42 
Thorax,  boundaries  of.  118 

dissection  of,  118 
Thyroid  body,  36 

structure  of,  37 

cartilage,  190 
TONGUE,  arteries  of,  206 

dissection  of,  201 

fibrous  septum  of,  206 

frsenum  of,  20'2 

glands  of,  204 

mucous  membrane  of,  202 


INDEX. 


691 


TON 


VEi 


TONGUE  (continued) 

muscular  fibres  of,  205 

nerves  of,  206 

papillae  of,  202 

taste  buds  of,  202 
Tonsils,  186 
Torcular  Herophili,  11 
Trabeculae  testis,  668 
Trachea,  169 
Tracheotomy,  40 
Transverse  meso-colon,  383 
TRIANGLES,  anterior  of  neck,  28 

digastric,  41 

of  Hesselbach,  369 

posterior  of  neck,  25 

of  Scarpa,  510 

sub-occipital,  242 

supra-clavicular,  27 
Trigone  of  bladder,  449 
Triticea  cartilage,  190 
Trochlea  of  superior  oblique  muscle,  211 
Tube,  Eustachian,  178,  181 

Fallopian,  464,  473 
Tuber  cinereum,  594 
Tubuli  seminiferi,  670 
Tunica  albuginea  of  the  ovary,  474 
testis,  667 

vaginalis,  667 

vasculosa,  667,  668 
Tympanum,  650 

boundaries  of,  650 

bones  of  the,  652 

blood-vessels  of,  654 


Uraehus,  372 

Ureter,  436 

Ureters,  relations  of,  394 

URETHRA,  bulb  of,  458 

female,  460 

side  view  of,  466 

lacuna  of,  454 

lymphatics  of,  465  . 

in  the  male,  438 

anatomy  of,  453 
UTKKVS,  467 

arteries  of,  466 

cervix  of,  467 

general  position  of,  463 

interior  of,  470 

ligaments  of,  465 

lymphatics  of,  469 

mouth  of,  468 

mucous  membrane  of,  472 


UTERUS  (continued) 

muscular  fibres  of,  472 

nerves  of,  468 
Utricle  of  labyrinth,  658 
Utriculus  of  prostate,  450 
Uvea,  638 
Uvula,  184 

of  bladder,  418 


Vagina.  462 

bulb  of,  462 

side  view  of,  466 

structure  of,  469 

sphincter  of,  $70 
Vullecula  of  cerebellum,  614 
Vilsalva,  sinuses  of,  129,  161,  162 
VALVES 

auriculo-ventricular,  left,  162 
right,  159 

Eustachian,  157 

of  Houston,  495 

ileo-csecal,  375,  495 

mitral  or  bicuspid,  162 

pulmonary  or  semilunar,  160 

tricuspid,  159 

of  Vieussens,  612 

of  Thebesius,  158,  164 
Valvulse  conniventes,  491 
Vas  aberrans,  671 

deferens,  437,  671 

spirale,  663 
Vasa  efferentia  testis,  670 

rscta,  670 
VEINS 

angular,  87 

anterior  jugular,  19 

axillary,  267 

basilic,  274,  286 

brachial,  279 

brachio-cephalic,  126 
left,  126 
right,  126 

cardiac  anterior,  163 
great,  163 
posterior,  163 

cephalic,  259,  274,  286 

circumflexa  ilii,  deep,  367 

superficial,  356 

comites  of  brachial  artery,  281 

common  iliac,  relations  of,  404 

coronary,  158,  163 

epigastric,  356 

external  jugular,  18 


092 


INDEX. 


VE1 

VEINS  (continued) 

external,  pudic,  356 

or  short  saphena,  525 
facial,  44,  87 
frontal,  87 
of  Galen,  10,  608 
hcemorrhoidal,  inferior,  434 
middle,  434 
superior,  434 
plexus,  435 
intercostal,  149 

superior,  69 
internal  jugular,  34 

mammary,  68,  121 

maxillary,  102 

or  long  saphena,  525 
lingual,  52 
lumbar,  404 
median,  274,  286 

basilic,  274 

cephalic,  274 

mediana  profunda,  274,  286 
mesenteric  inferior,  392 
superior,  391 
occipital,  56 
ophthalmic,  215 
ovarian,  475 
pampiniform,  671 
pharyngeal  plexus  of,  178 
popliteal,  544,  553 
prostatic  plexus  of,  432 
pterygoid  plexus  of,  87,  103 
pudic,  427 
radial,  285 
ranine,  52 
renal,  402 
salvatella,  285 
saphena,  internal,  499 

long  or  internal,  525 
short  or  external,  525 
short  or  posterior,  545,  548 
scapular  posterior,  68 
spermatic,  403 
spinal  system  of,  617 
subclavian,  70 
supra-scapular,  68 


ZIN 

YKINS  (continued) 

thyroid  inferior,  68 
superior,  54 

ulnar  anterior,  285 
posterior,  285 

uterine,  468 

vaginal  plexus  of,  466 

vena  portse,  388 

vertebral,  67 

vorticosse,  637 
VELUM 

interpositum,  579,  607 

posterior  medullary,  615 
Veneris  mons,  459 
Vena  cava,  inferior,  404 

relations  of,  404 

superior,  127 
Vena  azygos  major,  141,  170 

minor,  141 
Venesection,  veins  and  nerves,  concerned. 

in,  274 
Ventricles,  fifth,  604 

fourth,  612 

lateral,  602 

left,  162 

right,  158 

septum  of,  604 

third,  609 

Veru  montanum,  450 
Vesicles,  graafian,  474 
Vesiculse  seminales,  437,  452 
Vestibule  in  female  pudenda,  460 

of  internal  ear,  655 
Villi,  structure  of,  491 
Vocal  cords,  false  or  superior,  195 

true  or  inferior,  195 


Willis,  circle  of,  582 
Winslow,  foramen  of,  381 

posterior  ligament  of,  546 
Wrisberg,  nerve  of,  262 


Zinn,  zone  of,  645 


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The  author  has  embodied  in  this  work  the  experience  gained  by  him  during  twenty 
years  of  Surgical  Teaching.  It  comprises  all  the  operations  that  are  required  in  Ordinary 
Surgical  Practice.  He  has  selected  for  illustration  and  description  those  methods  which 
appear  to  give  the  best  results  in  practice,  referring  to  the  errors  likely  to  occur  and  the 
best  methods  of  avoiding  them. 


GODLEE'S  ATLAS  OF  HUMAN  ANATOMY. 

An  Atlas  of  Human  Anatomy,  illustrating  most  of  the  ordinary  Dissections  and  many  not 
usually  practised  by  the  Student.  Accompanied  by  References  and  an  Explanatory 
Text.  By  RICKMAN  JOHN  GODLEE,  M.S.,  F.R.C.S.,  Fellow  of  University  College; 
Assistant-Surgeon  to  University  College  Hospital,  and  Senior  Demonstrator  of  Anat- 
omy in  University  College.  To  be  completed  in  Twelve  or  Thirteen  Bi- Monthly 
Farts,  Large  Folio  Size.  Containing  Four  Plates,  Two  Figures  to  each  Plate,  Colored, 
,-nd  Twenty-four  Octavo  Pages  of  Letter-press,  forming,  when  complete,  a  large  Folio 
Volume  of  Plates,  with  References,  and  an  Octavo  Volume  of  Letter-press.  PARTS 
I.  to  VII.  Now  READY.  Price  of  each  Part,  $2.50. 

SCHULTZE'S  LECTURE  DIAGRAMS. 

LECTURE  DIAGRAMS  FOR  INSTRUCTION  IN  PREGNANCY  AND  MIDWIFERY.  Twenty  Plates 
of  the  largest  Imperial  size,  printed  in  colors.  Drawn  and  Edited  with  Explanatory 
Notes,  and  a  410  volume  of  letter-press.  By  DR.  B.  S.  SCHULTZE,  Professor  of  Mid- 
wifery at  the  University  of  Jena.  Prices,  in  sheets,  $15.00.  Handsomely  mounted 
on  rollers  for  hanging  up.  Price $30.00 

BRAUNE'S  ATLAS  OF  TOPOGRAPHICAL  ANATOMY. 

Containing  Thirty-Four  Full  Page  Photo-Lithographic  Plates,  after  Plane  Sections  of  Frozen 
Bodies,  and  Forty-Six  large  Wood  Engravings.  The  Photo-Lithographic  Plates  have 
Marginal  References,  and  each  Plate  is  accompanied  with  Full  Explanatory  Text. 
By  WILHELM  BRAUNE,  Professor  of  Anatomy  in  the  University  of  Leipsic.  Trans- 
lated by  EDWARD  BELLAMY,  F.R.C.S.,  Senior  Assistant-Surgeon  to,  and  Lecturer  on 
Anatomy  and  Teacher  of  Operative  Surgery  at,  the  Charing  Cross  Hospital.  Forming 
a  large  Imperial  Octavo  volume.  Price,  bound  in  cloth,  $12.00  ;  half  morocco,  gilt 
head,  $14.00. 

SAVAGE'S  FEMALE  PELVIC  ORGANS. 

The  Surgery,  Surgical  Pathology,  and  Surgical  Anatomy  of  the  Female  Pelvic  Organs. 
In  a  Series  of  Elegantly-Colored  Plates  and  Diagrams  taken  from  Nature ;  with  Com- 
mentaries, Notes,  and  Cases.  By  HENRY  SAVAGE,  M.D.,  one  of  the  Consulting  Med- 
ical Officers  of  the  Samaritan  Hospital  for  Women.  Third  Edition,  revised  and 
greatly  extended.  With  an  additional  Plate,  Thirty -Six  Engravings,  and  Special  Illus- 
trations of  the  Operations  on  Vesico- vaginal  Fistula,  Ovariotomy,  and  Penneal  Opera- 
tions. A  large  410  volume.  Price,  $12.00. 

ROBERTI  FRORIEPI  ATLAS  ANATOMICUS. 

Atlas  Anatomicus  Partium  Corporis  Humani  Per  Strata  Dispositarum  Imagines.  In  Tab- 
udus  XXX.  Ab  Augusto  Andorffo  Delmeatas  Ferroque  Incisas,  Exhibens.  Editio 
Sexta,  non  Mutata.  The  Thirty  Plates  contain  in  all  Seventy-six  Figures,  with  Very 
Full  References  to  all  the  Muscles,  Arteries,  Ligaments,  etc.  Making  one  of  the 
Finest  Anatomical  Works  ever  Published.  Printed  on  Heavy  Paper.  I  Vol.,  Quarto. 
Plain  Plates,  $4.00 ;  Colored.  Price $10.00 

FERBER'S  DIAGRAM  OF  THE  THORAX. 

A  Model  Diagram  of  the  Thorax  and  Upper  Part  of  the  Abdomen.  By  A.  FERBER. 
This  is  a  Colored  Lithographic  Representation  in  a  Dissected  Form,  or  four  leaves 
showing  the  above  organs  as  they  are  met  with  in  the  different  stages  of -an  Autopsy 
or  in  Dissections,  and  will  prove  of  service  in  showing  the  exact  Position  of  the  Large 
Viscera  and  Blood-Vessels  in  Post-Mortem  Examinations.  It  also  possesses  the  great 
merit  of  Clearness  and  Portability.  On  Heavy  Paper.  Bound  on  Canvas  and  in 
Wooden  Frame.  4to  size.  Price $2.25 

JONES'  AURAL  ATLAS. 

AN  ATLAS  OF  DISEASES  OF  THE  MEMBRANA  TYMPANI.  With  Sixty-three  Colored  Fig- 
ures, and  appropriate  letter-press.  Quarto,  bound  in  cloth.  Price $6.00 


T  H  E 

PRACTITIONER  AND  STUDENTS  GUIDE  SERIES. 


Under  this  general  title  the  publishers  are  issuing  a  New  Series  of  Medi- 
cal Text-Books,  or  Hand-Books  for  Practitioners,  Moderate  in  Size  and 
Price,  and  comprising  a  Series  of  Treatises  on  the  Elementary  and  Practi- 
cal Branches  of  Medicine.  Each  one  complete  in  itself.  Prepared  by  Men 
of  Established  Reputation.  Containing  a  Condensed  Summary  of  the 
Existing  State  of  the  Science  adapted  to  the  wants  of  all  classes  of  Medical 
Men.  SOLD  SEPARATELY. 

NOW  READY. 

1.  The  Student's  Guide  to  the  Practice  of  Midwifery.     By  D. 

LLOYD  ROBERTS,  M.  D.,  Vice-President  of  the  Obstetrical  Society  of  London, 
Physician  to  St.  Mary's  Hospital,  Manchester.  With  95  Engravings.  Price,  $2.00 

2.  The  Student's  Guide  to  the  Diseases  of  Women.     With  numerous 

Illustrations.  By  ALFRED  LEWIS  GALABIN,  M.D.,  Assistant  Obstetric  Physi- 
cian, and  Joint  Lecturer  on  Midwifery,  Guy's  Hospital.  I2mo.  Cloth 2.00 

3.  The  Student's  Guide  to  Dental  Anatomy  and  Surgery.    By 

HENRY  E.  SEWILL,  M.  R.  C.  S.  Eng.,  L.D.  S.,  Dental  Surgeon  to  the  West 
London  Hospital.  With  77  Engravings 1.50 

4.  The  Complete  Hand-Book  of  Obstetric  Surgery,  or,  Short  Rules  of 

Practice  in  Every  Emergency,  from  the  Simplest  to  the  most  Formidable  Oper- 
ations in  the  Practice  of  Surgery.  By  CHARLES  CLAY,  M.  D.,  Fellow  of  the 
London  Obstetrical  Society,  etc.  With  101  Illustrations 2.00 

5.  Surgical  Emergencies.     A   Manual   Containing  Concise   Descriptions  of 
,         Various  Accidents    and    Emergencies,  with   Directions  for   their    Immediate 

Treatment.  By  W.  P.  SWAIN,  M.  D.,  Surgeon  to  the  Royal  Albert  Hospital, 
etc.  With  82  Wood  Engravings 2.00 

6.  A  Manual  of  Minor  Surgery  and  Bandaging,  for  the  Use  of 

House  Surgeons,  Dressers,  and  Junior  Practitioners.  By  CHRISTOPHER 
HEATH,  F.  R.  C.  S.,  Surgeon  to  University  College  Hospital,  etc.  With  a 
Formulae  and  86  Illustrations • 2.oc 

7.  A  Hand-Book  on  the  Diseases  and  Injuries  of  the  Ear.    By 

W.  B.  DALBY,   F.  R.  C.  S.,   Aural   Surgeon  to  St.  George's  Hospital.     With 

21  Illustrations.... 1.50 

8.  The  Student's  Hand-BooJc  of  the  Practice  of  Medicine.    With 

Microscopic  and  other  Illustrations.  By  Prof.  CHARTERIS,  of  Glasgow  Uni- 
versity    2.OO 

9.  Practical   Gynaecology.     A   Hand-book  for  Students  and  Practitioners. 

With  Illustrations.     By  HEYWOOD  SMITH,  M.D.,  Physician  to  the  Hospital 

for  Women,  etc 1.50 

A  Guide  to  Surgical  Diagnosis.     By  CHRISTOPHER  HEATH,  F.  R.  C.  S., 

Surgeon  to  University  College  Hospital,  etc.     I2mo.     Cloth I   50' 

Practical  Surgery.  Including  SURGICAL  DRESSINGS,  BANDAGING  LIGATIONS, 
and  AMPUTATIONS.  By  J.  EWING  MEARS,  M.D.,  Demonstrator  of  Surgery  in 
Jefferson  Medical  College,  etc.,  etc.  227  Illustrations 2.00 

Atthill's  Clinical  Lectures  on  Diseases  Peculiar  to  Women.  Fifth 

Edition.  Revised  and  Enlarged.  With  numerous  Illustrations 2.25 

LINDSAY  &  BLAKISTON,  Publishers, 

25  South  Sixth  Street,  Philadelphia. 


MEDICAL,  DENTAL, 

PHARMACEUTICAL  AND   SCIENTIFIC   BOOKS 

PUBLISHED  BY 

LINDSAY  &  BLAKISTON,  Philadelphia. 
AITKEN  (WILLIAM),  M.  D., 

Professor  of  Pathology  in  the  Army  Medical  School,  &c. 

THE   SCIENCE  AND    PRACTICE   OF  MEDICINE.     THIRD 

American,  from  the  Sixth  London  Edition.  Thoroughly  Revised, 
Remodelled,  many  portions  Rewritten,  with  Additions  almost  equal  to 
a  Third  Volume,  and  numerous  additional  Illustrations,  without  any 
increase  in  bulk  or  price.  Containing  a  Colored  Map  showing  the 
Geographical  Distribution  of  Disease  over  the  Globe,  a  Lithographic 
Plate,  and  nearly  200  Illustrations  on  Wood. 

Two  volumes,  royal  octavo,  bound  in  cloth,  price,     .         .         $12.00 
"  "  "  "          leather,  .         .  14.00 

For  eighteen  months  Dr.  Aitken  has  been  engaged  in  again  carefully  revising  this  Great 
Work,  and  adding  to  it  many  valuable  additions  and  improvements,  amounting  in  the  ag- 
gregate almost  to  a  volume  of  new  matter,  included  in  which  will  be  found  the  adoption  and 
incorporation  in  the  text  of  the  "  New  Nomenclature  of  the  Royal  College  of  Physicians  of 
London; "  to  which  are  added  the  Definitions  and  the  Foreign  Equivalents  for  their  English 
names ;  the  New  Classification  of  Disease  as  adopted  by  the  Royal  College  of  Physicians,  &c. 

The  American  editor,  MEREDITH  CLYMER,  M.  D.,  has  also  added  to  it  many 
valuable  articles,  with  special  reference  to  the  wants  of  the  AMERICAN  PRAC- 
TITIONER. 

The  work  is  now,  by  almost  universal  consent,  both  in  England  and  the  United  States, 
acknowledged  to  be  in  advance  of  all  other  works  on  The  Science  and  Practice  of  Medicine. 
It  is  a  most  thorough  and  complete  TEXT-BOOK  for  students  of  medicine,  following  such  a 
systematic  arrangement  as  will  give  them  a  consistent  view  of  the  main  facts,  doctrines,  and 
practice  of  medicine,  in  accordance  with  accurate  physiological  and  pathological  principles 
and  the  present  state  of  science.  For  the  practitioner  it  will  be  found  equally  acceptable  as 
a  work  of  reference. 

ALLINGHAM  (WILLIAM),  F.  R.  C.  S., 

Surgeon  to  St.  Mark's  Hospital  for  Fistula,  &c. 

FISTULA,  HAEMORRHOIDS,  PAINFUL  ULCER,  STRICT- 
URE, PROLAPSUS,  and  other  Diseases  of  the  Rectum,  their  Diagnosis 
and  Treatment.  Third  Edition,  Revised  and  Enlarged  by  the  Author. 
Octavo.  Price  .........  $3-°o 

This  book  has  been  well  received  by  the  Profession ;  the  first  edition  sold  rap- 
idly ;  the  present  one  has  been,  revised  by  the  author,  and  some  additions  made 
chiefly  as  to  the  mode  of  treatment. 

The  Medical  Press  and  Circular,  speaking  of  it,  says :  "  No  book  on  this  special  subject 
can  at  all  approach  Mr.  Allingham's  in  precision,  clearness,  and  practical  good  sense." 

The  London  Lancet :  "  As  a  practical  guide  to  the  treatment  of  affections  of  the  lower 
bowel,  this  book  is  worthy  of  all  commendation." 

The  Edinburgh  Monthly :  "  We  cordially  recommend  it  as  well  deserving  the  careful  study 
of  Physicians  and  Surgeons." 


ATTHILL  (LOMBE),  M.  D., 

Fellow  and  Examiner  in  Midwifery,  King  and  Queen's  College  of  Physicians,  Dublin. 

CLINICAL  LECTURES  ON  DISEASES  PECULIAR  TO  WO 

MEN.     Fifth  Edition,  Revised  and  Enlarged,  with  numerous  Illustra- 
tions.    Price $2.25 

The  value  and  popularity  of  this  book  is  proved  by  the  rapid  sale  of  the  first  edition, 
which  was  exhausted  in  less  than  a  year  from  the  time  of  its  publication.  It  appears  tn 
possess  three  great  merits  :  First,  It  treats  of  the  diseases  very  common  to  females.  Second 
It  treats  of  them  in  a  thoroughly  clinical  and  practical  manner.  Third,  It  is  concise,  orig- 
inal, and  illustrated  by  numerous  cases  from  the  author's  own  experience.  His  style  is  clear 
and  the  volume  is  the  result  of  the  author's  large  and  accurate  clinical  observation  recorder 
in  a  remarkable,  perspicuous,  and  terse  manner,  and  is  conspicuous  for  the  best  qualities  G? 
a  practical  guide  to  the  student  and  practitioner.  —  British  Medical  Journal. 

ADAMS  (WILLIAM),  F.  R.  C.  S., 

Surgeon  to  the  Royal  Orthopedic  and  Great  Northern  Hospitals. 

CLUB-FOOT:  ITS  CAUSES,  PATHOLOGY,  AND  TREAT- 
MENT. Being  the  Jacksonian  Prize  Essay  of  the  Royal  College  of 
Surgeons.  A  New  Revised  and  Enlarged  Edition,  with  106  Illustrations 
engraved  on  Wood,  and  Six  Lithographic  Plates.  A  large  Octavo 
Volume.  Price  .  .  tfq.oo 


ADAMS  (ROBERT),  M.  D., 

Regius  Professor  of  Surgery  in  the  University  of  Dublin,  &.C.,  &c. 

RHEUMATIC  GOUT,  OR  CHRONIC  RHEUMATIC  ARTHRI- 
TIS OF  ALL  THE  JOINTS.  The  Second  Edition.  Illustrated  by 
numerous  Woodcuts,  and  a  quarto  Atlas  of  Plates.  2  Volumes. 
Price $7-5° 

ALTHAUS  (JULIUS),  M.D., 

Physician  to  the  Infirmary  of  Epilepsy  and  Paralysis. 

A  TREATISE  ON  MEDICAL  ELECTRICITY,  Theoretical  and 
Practical,  and  its  Use  in  the  Treatment  of  Paralysis,  Neuralgia,  and  other 
Diseases.  Third  Edition,  Enlarged  and  Revised,  with  One  Hundred 
and  Forty-six  Illustrations.  In  one  volume  octavo.  Price  .  $6.00 

ALLEN  (ALFRED"H.).  F.  C.  S  , 

Lecturer  on  Chemistry  at  the  Sheffield  Schorl  of  Medicine. 

AN  INTRODUCTION  TO  THE  PRACTICE  OF  COMMER- 
CIAL ORGANIC  ANALYSIS.  Being  a  Treatise  on  the  Properties, 
Proximate  Analytical  Examination,  and  Modes  of  Assaying  the  various 
Organic  Chemicals  and  Preparations  employed  in  the  Arts,  Manufac- 
tures, Medicine,  etc.  ;  with  Concise  Methods  for  the  Detection  and 
Determination  of  their  Impurities,  Adulterations,  and  Products  of  De- 
composition. Vol.  I. —  Cyanogen  Compounds,  Alcohols  and  their 
Derivatives,  Phenols,  Acids,  etc.  Price  .  .  .  .  $3-5° 

AGNEW  (D.  HAYES),  M.D., 

^  \  / 

Professor  of  Surgery  in  the  University  of  Pennsylvania. 

THE  LACERATIONS  OF  THE  FEMALE  PERINEUM,  AND 
VESICO-VAGINAL  FISTULA,  their  History  and  Treatment,  with 
numerous  Illustrations.  Octavo.  Price  .  .  .  .  $1.50 


ACTON  (WILLIAM),  M.R.C.S.,  ETC. 

THE  FUNCTIONS  AND  DISORDERS  OF  THE  REPRODUC- 
TIVE ORGANS.  In  Childhood,  Youth,  Adult  Age,  and  Advanced 
Life,  considered  in  their  Physiological,  Social,  and  Moral  Relations. 
Fourth  American  from  the  Fifth  London  Edition.  Carefully  revised  by 
the  Author,  with  additions.  .  .  .  .  .  .  $2-5° 

Mr.  Acton  has  done  good  service  to  society  by  grappling  manfully  with  sexual  vice,  and 
wi  trust  that  others,  whose  position  as  men  of  science  and  teachers  enable  them  to  speak 
with  authority,  will  assist  in  combating  and  arresting  the  evils  which  it  entails.  The  spirit 
which  pervades  his  book  is  one  which  does  credit  equally  to  the  head  and  to  the  heart  of  the 
author.  —  British  and  Foreign  Medico- Chirurgicul  Review. 

AVELINcT(j~H.),  M-  D-> 

Physician  to  Chelsea  Hospital  for  Diseases  of  Womeni 

THE  INFLUENCE  OF  POSTURE  ON  WOMEN  IN  GYNECIC 
AND  OBSTETRIC  PRACTICE.  Octavo.  Cloth.  Price  .  $2.00 

ANSTIE  (FRANCIS  E.),  M.D., 

Lecturer  on  Materia  Medica  and  Therapeutics,  etc. 

STIMULANTS  AND  NARCOTICS.  Their  Mutual  Relations,  with 
Special  Researches  on  the  Action  of  Alcohol,  Ether,  and  Chloroform 
on  the  Vital  Organism.  Octavo.  .  .  .  .  $3-°° 

ANDERSON   (M'CALL),  M.D., 

Professor  of  Clinical  Medicine  in  the  University  of  Glasgow,  &c. 

ECZEMA.  The  Pathology  and  Treatment  of  the  various  Eczema- 
tous  Affections  or  Eruptions  of  the  Skin.  The  Third  Revised  and  En- 
larged Edition.  Octavo.  Price  .  .  .  .  .  .  $2.50 

BUZZARD'S  CLINICAL   ASPECTS    OF    SYPHILITIC    NER- 
VOUS AFFECTIONS.     i2mo.     Cloth.     Price     .  .     $1.75 

BASHAM'S  AIDS  TO  THE   DIAGNOSIS  OF  DISEASES   OF 

THE  KIDNEYS.     Sixty  Illustrations $1.75 

BASHAM  ON  DROPSY,  AND  ITS  CONNECTION  WITH 
DISEASES  OF  THE  KIDNEYS,  HEART,  LUNGS,  AND  LIVER. 

With  Sixteen  Plates.     Third  Edition.     Octavo        .         .         .     $4.50 

BARTH    AND    ROGER'S    MANUAL    OF   AUSCULTATION 

AND  PERCUSSION.     From  the  Sixth  French  Edition          .      $1.00 

BRADLEY'S  MANUAL  OF  COMPARATIVE  ANATOMY 
AND  PHYSIOLOGY.  Sixty  Illustrations.  Third  Edition  .  $2.00 

BERNAY'S  (ALBERT  j.),  Ph.  D. 

Professor  of  Chemistry  at  St.  Thomas's  Hospital, 

NOTES  FOR  STUDENTS  IN  CHEMISTRY.  Compiled  from 
Fowne's  and  other  Manuals.  The  Sixth  Edition.  Cloth  .  $1.25 

BY  SAME  AUTHOR. 

THE    STUDENT'S     GUIDE    TO     MEDICAL    CHEMISTRY. 

With  Illustrations.     Preparing. 


BEALE  (LIONEL  s.),  M.D. 

DISEASE  GERMS:  AND  ON  THE  TREATMENT  OF  DIS- 
EASES CAUSED  BY  THEM. 

PART      I.— SUPPOSED  NATURE  OF  DISEASE  GERMS. 
PART    II.  — REAL  NATURE  OF  DISEASE  GERMS. 
PART  III.— THE  DESTRUCTION  OF  DISEASE  GERMS. 

Second  Edition,  much  enlarged,  with  Twenty-eight  full-page  Plates, 
containing  117  Illustrations,  many  of  them  colored.  Demy  Octavo. 
Price  .  .  .  .  .  .  .  .  .  .  $4.00 

This  new  edition,  besides  including  the  contents  revised  and  enlarged  of  the  two  former 
editions  published  by  Dr.  Beale  on  Disease  Germs,  has  an  entirely  new  part  added  on  "  The 
Destruction  of  Disease  Germs." 

SAME  AUTHOR. 

BIOPLASM.  A  Contribution  to  the  Physiology  of  Life,  or  an  Intro- 
duction to  the  Study  of  Physiology  and  Medicine,  for  Students.  With 
Numerous  Illustrations.  Price  .  .  .  .  .  $2.25 

This  volume  is  intended  as  a  TEXT-BOOK  for  Students  of  Physiology,  explaining  the  nature 
of  some  of  the  most  important  changes  which  are  characteristic  of  and  peculiar  to  living 
beings. 

PROTOPLASM,  OR  MATTER  AND  LIFE.  Third  Edition,  very 

much   Enlarged.     Nearly  350  pages.     Sixteen  Colored   Plates.     One 

volume.     Price      .         .         .         .         .         .  .•         .         .     $3.00 

PART  I.  DISSENTIENT.      PART  II.  DEMONSTRATIVE.  PART  III.  SUGGESTIVE. 

HOW  TO  WORK  WITH  THE  MICROSCOPE.  Fourth  Edition, 
containing  400  Illustrations,  many  of  them  colored.  Octavo.  Price 

This  work  is  a  complete  manual  of  microscopical  manipulation,  and  contains  a  full  descrip- 
tion of  many  new  processes  of  investigation,  with  directions  for  examining  objects  under  the 
highest  powers,  and  for  taking  photographs  of  microscopic  objects. 

ON  KIDNEY  DISEASES,  URINARY  DEPOSITS,  AND  CAL- 
CULOUS  DISORDERS.  Including  the  Symptoms,  Diagnosis,  and 
Treatment  of  Urinary  Diseases.  With  full  Directions  for  the  Chemical 
and  Microscopical  Analysis  of  the  Urine  in  Health  and  Disease.  The 
Third  Edition.  Seventy  Plates,  415  figures,  copied  from  Nature. 
Octavo.  Price  .........  $10.00 

THE  USE  OF  THE  MICROSCOPE  IN  PRACTICAL  MEDI- 
CINE. For  Students  and  Practitioners,  with  full  directions  for  exam- 
ining the  various  secretions,  &c.,  in  the  Microscope.  Fourth  Edition. 
500  Illustrations.  Octavo.  Much  enlarged.  Price  .  .  $7.50 

BLOXAM  (c.  L.), 

Professor  of  Chemistry  in  King's  College,  London. 

CHEMISTRY,  INORGANIC  AND  ORGANIC.  With  Experi- 
ments and  a  Comparison  of  Equivalent  and  Molecular  Formulae.  With 
276  Engravings  on  Wood.  Third  London  Edition,  revised.  Octavo. 
Price,  in  cloth,  $4.00;  leather,  .  .  .  .  .  $5-°° 

SAME  AUTHOR. 

LABORATORY  TEACHING;  OR  PROGRESSIVE  EXER- 
CISES IN  PRACTICAL  CHEMISTRY.  Fourth  Edition.  With 
Eighty-nine  Engravings.  Crown  Octavo.  Price  .  .  .  $1.75 


BENNETT  (j.  HENRY),  M.  D. 

NUTRITION  IN  HEALTH  AND  DISEASE.  A  Contribution 
to  Hygiene  and  to  Clinical  Medicine.  Third  Edition,  Revised  and 
Enlarged.  Octavo.  Cloth.  Price  ...  .  $2.50 

BY  SAME  AUTHOR. 

THE  TREATMENT  OF  PULMONARY  CONSUMPTION  BY 
HYGIENE,  CLIMATE,  AND  MEDICINE.  With  an  Appendix  on 
the  Sanitaria  of  the  United  States,  Switzerland,  and  the  Balearic  Isl- 
ands. The  Third  Edition,  much  Enlarged.  Octavo.  Price  .  $2.50 

• 

BUCKNILL(joHN  CHARLES),  M.D.,  &  TUKE  (DANIEL  H.),M.D. 

A  MANUAL  OF  PSYCHOLOGICAL  MEDICINE:  containing  the 
Lunacy  Laws,  the  Nosology,  CEtiology,  Statistics,  Description,  Diagno- 
sis, Pathology  (including  Morbid  Histology),  and  Treatment  of  Insanity. 
Fourth  Edition,  much  enlarged,  with  Twelve  Lithographic  Plates,  and 
numerous  Illustrations.  Octavo.  Price  .  .  .  .  $8.00 

This  edition  will  contain  a  number  of  pages  of  additional  matter,  and,  in  consequence  of 
recent  advances  in  Psychological  Medicine,  several  chapters  will  be  rewritten,  bringing  the 
Classification,  Pathology,  and  Treatment  of  Insanity  up  to  the  present  time. 

BURNETT  (CHARLES  H.),  M.  D., 

Aurist  to  {he  Presbyterian  Hospital,  &c. 

HEARING,  AND  HOW  TO  KEEP  IT.  (Vol.  I.,  American  Health 
Primers.)  With  Illustrations.  Cloth.  Price  .  .  .  $0.50 

BIDDLE  OOHN~B.),  M.  D., 

Professor  of  Materia  Medicaand  Therapeutics  in  the  Jefferson  Medical  College,  Philadelphia,  &o. 

MATERIA  MEDICA,  FOR  THE  USE  OF  STUDENTS.  With 
Illustrations.  Eighth  Edition,  Revised  and  Enlarged.  Price  $4.00 

This  new  and  thoroughly  revised  edition  of  Professor  Biddle's  work  has  incorporated  in 
it  all  the  improvements  as  adopted  by  the  New  United  States  Phamiacopoeia  just  issued.  It 
is  designed  to  present  the  leading  facts  and  principles  usually  comprised  under  this  head  as 
set  forth  by  the  standard  authorities,  and  to  fill  a  vacuum  which  seems  to  exist  in  the  want 
of  an  elementary  work  on  the  subject.  The  larger  works  usually  recommended  as  text-books 
in  our  Medical  schools  are  too  voluminous  for  convenient  use.  This  will  be  found  to  contain, 
in  a  condensed  form,  all  that  is  most  valuable,  and  will  supply  students  with  a  reliable  guide 
to  the  course  of  lectures  on  Materia  Medica  as  delivered  at  the  various  Medical  schools  in 
the  United  States. 

BALFOUR^cTw.),  M.  D., 

Physician  to  the  Royal  Infirmary,  Edinburgh)  Lecturer  on  Clinical  Medicine,  &c. 

CLINICAL  LECTURES  ON  DISEASES  OF  THE  HEART  AND 
AORTA.  With  Illustrations.  Octavo.  Price  .  .  .  $4.00 

BYFORD  (\v~~rT),  A.M.,  M.D., 

Professor  of  Obstetrics  and  Diseases  of  Women  and  Children  in  the  Chicago  Medical  College,  &c. 

PRACTICE  OF  MEDICINE  AND  SURGERY.  Applied  to  the 
Diseases  and  Accidents  incident  to  Women.  Second  Edition,  Revised 
and  Enlarged.  Octavo.  Price 

SAME  AUTHOR. 

ON  THE  CHRONIC  INFLAMMATION  AND  DISPLACEMENT 

OF  THE  UNIMPREGNATED  UTERUS.     A  New,  Enlarged,  and 

Thoroughly  Revised  Edition,  with  Numerous  Illustrations.   8vo.    $2.50 

Dr.  Byford  writes  the  exact  present  state  of  medical  knowledge  on  the  subjects  presented; 

and  does  this  so  clearly,  so  concisely,  so  truthfully,  and  so  completely,  that  his  book  on  the 

uterus  will  always  meet  the  approval  of  the  profession,  and  be  everywhere  regarded  as  a 

popular  standard  work.  —  Buffalo  Medical  and  Surgical  Journal. 


10 
BLACK  (D.  CAMPBELL),  M.  D., 

L.  R.  C.  S.  Edinburgh,  Member  of  the  General  Council  of  the  University  of  Glasgow,  &c.,  &c. 

THE  FUNCTIONAL  DISEASES  OF  THE  RENAL,  URINARY, 

and  Reproductive  Organs,  with  a  General  View  of  Urinary  Pathology. 

Price $2.00 

The  style  of  the  author  is  clear,  easy,  and  agreeable,  .  .  .  his  work  is  a  valuable  contri- 
bution to  medical  science,  and  being  penned  in  that  disposition  of  unprejudiced  philosophical 
inquiry  which  should  always  guide  a  true  physician,  admirably  embodies  the  spirit  of  its 
opening  quotation  from  Professor  Huxley.  —  Philada.  Med.  Times. 

BY  SAME  AUTHOR. 
LECTURES   ON   BRIGHT'S    DISEASE  OF  THE   KIDNEYS. 

Delivered  at  the  Royal  Infirmary  of  Glasgow.     With  20  Illustrations, 
engraved  on  Wood.     One  volume,  octavo,  in  Cloth.     Price     .     $1.50 

BENTLEY  AND  TRIMEN'S 

MEDICINAL  PLANTS.  A  New  Illustrated  Work,  now  Publish- 
ing in  Monthly  Parts.  Thirty-seven  Parts  now  ready.  Eight  Colored 
Plates  in  each  Part.  Price,  each,  ......  $2.00 

This  work  includes  full  botanical  descriptions,  and  an  account  of  the  properties  and  uses 
of  the  principal  plants  employed  in  medicine,  especial  attention  being  paid  to  those  which 
are  officinal  in  the  British  and  United  States  Pharmacopoaias.  The  plants  which  supply 
food  and  substances  required  by  the  sick  and  convalescent  will  be  also  included.  Each  spe- 
cies will  be  illustrated  oy  a  colored  plate  drawn  from  nature. 

BEASLEY  (HENRY). 

THE  BOOK  OF  PRESCRIPTIONS.  Containing  over  3000 
Prescriptions,  collected  from  the  Practice  of  the  most  Eminent  Physi- 
cians and  Surgeons — English,  French,  and  American;  comprising  also 
a  Compendious  History  of  the  Materia  Medica,  Lists  of  the  Doses  of  all 
Officinal  and  Established  Preparations,  and  an  Index  of  Diseases  and 
their  Remedies.  Fifth  Edition,  Revised  and  Enlarged.  Price  $2.25 

BY  SAME  AUTHOR. 

THE  POCKET  FORMULARY:  A  Synopsis  of  the  British  and 
Foreign  Pharmacopoeias.  Tenth  Revised  Edition.  Price  .  $2.25 

THE  DRUGGIST'S  GENERAL  RECEIPT  BOOK  AND  VETERI- 
NARY FORMULARY.  Eighth  Edition.  Just  Ready.  Price,  $2.25 

BIRCH  (s.  B.),  M.  D., 

Member  of  the  Royal  College  of  Physicians,  &c. 

CONSTIPATED  BOWELS ;  the  Various  Causes  and  the  Different 
Means  of  Cure.  Third  Edition.  Price  .  .  .  .  $1.00 

BRAUNE— BELLAMY. 

AN  ATLAS  OF  TOPOGRAPHICAL  ANATOMY.  After  Plane 
Sections  of  Frozen  Bodies,  containing  Thirty-four  Full-page  Photo- 
graphic Plates  and  numerous  other  Illustrations  on  Wood.  By  WILHELM 
BRAUNE,  Professor  of  Anatomy  in  the  University  of  Leipzig.  Trans- 
lated and  Edited  by  EDWARD  BELLAMY,  F.  R.  C.  S.,  Senior  Assistant  Sur- 
geon to,  and  Lecturer  on  Anatomy  and  Teacher  of  Operative  Surgery 
at,  the  Charing  Cross  Hospital,  London.  A  large  quarto  volume. 
Price  in  cloth,  $12.00  ;  half  morocco,  .....  $14.00 


11 

COHEN   (i.  SOLIS),  M.D. 

Lecturer  on  Laryngoscopy  and  Diseases  of  the  Throat  and  Chest  in  Jefferson  Medical  College. 

ON  INHALATION.     ITS  THERAPEUTICS  AND  PRACTICE 

Including  a  Description  of  the  Apparatus  employed,  &c.     With  Cases 
and  Illustrations.     A  New  Enlarged  Edition.     Price        .         .     $2.50 

SAME  AUTHOR. 
CROUP.     In  its  Relations  to  Tracheotomy.     Price         .         .    $1.00 

CARSON  (JOSEPH),  M.D., 

•         Professor  of  Materia  Medica  and  Pharmacy  in  the  University. 

A  HISTORY  OF  THE  MEDICAL  DEPARTMENT  OF  THE 
UNIVERSITY  OF  PENNSYLVANIA,  from  its  Foundation  in  1765: 
with  Sketches  of  Deceased  Professors,  &c.  ....  $2.00 

^f / 

CHARTERIS  (MATHEW),  M.  D., 

Member  of  Hospital  Staff  and  Professor  in  University  of  Glasgow. 

STUDENTS'  HAND-BOOK  OF   THE   PRACTICE  OF  MEDI- 
CINE.     With  Microscopic  and  other  Illustrations.     Price         .      $2.00 

Tli  is  book  forms  one  volume  of  the  Students'  Guide  Series,  or  Text-Books,  now  in  course 
of  publication- 

CARPENTER  (w.  B.),  M.D.,  F.R.S. 

THE   MICROSCOPE   AND    ITS   REVELATIONS.      The   Fifth 

London  Edition,  Revised  and  Enlarged,  with  more  than  500  Illustra- 
tions.   .         .         .         .         .         .         .          .         .          .  $5-oo 

CORR  (L.  H.),  M.D. 

OBSTETRIC    CATECHISM,  or  Obstetrics   reduced  to  Questions 

and  Answers.     With  Numerous  Illustrations.     Price         .         .     £2.00 

CHAVASSE  (P.  HENRY),  F.R.C.S., 

Author  of  Advice  to  a  Wife,  Advice  to  a  Mother,  &c. 

APHORISMS  ON   THE   MENTAL   CULTURE  AND  TRAIN- 
ING OF  A  CHILD,  and  on  various  other  subjects  relating  to  Health 
and  Happiness.     Addressed  to  Parents.     Price         .         .         .     $1.00 
Dr.  Cliayasse's  works  have  been  very  favorably  received  and  had  a  large  circulation,  the 
value  of  his  advice  to  WIVES  and  MOTHERS  having  thus  been  very  generally  recognized. 
This  book  is  a  sequel  or  companion  to  them,  and  it  will  be  found  both  valuable  and  important 
to  all  who  have  the  care  of  families,  and  who  want  to  bring  up  their  children  to  become  useful 
men  and  women.     It  is  full  of  fresh  thoughts  and  graceful  illustrations. 

CLARKE  (W.FAIKLIE),  M.D., 

Assistant  Surgeon  to  Charing  Cross  Hospital, 

CLARKE'S   TREATISE  ON  DISEASES   OF  THE  TONGUE. 

With  Lithographic  and  Wood-cut  Illustrations.     Octavo.     Price  $4.50 
It  contains  The  Anatomy  and  Physiology  of  the  Tongue,  Importance  of  its  Minute  Exam- 
ination, Its  Congenital  Defects,  Atrophy,  Hypertrophy,  Parasitic  Diseases,  Inflammation, 
Syphilis  and  its  effects,  Various  Tumors  to  which  it  is  subject,  Accidents,  Injuries,  &c.,  &c. 

COOPER  (s.). 

A  DICTIONARY  OF  PRACTICAL  SURGERY  AND  ENCY- 
CLOPEDIA OF  SURGICAL  SCIENCE.  New  Edition,  brought 
down  to  the  present  time.  By  SAMUEL  A.  LANE,  F.R.C.S.,  assisted  by 
other  eminent  Surgeons.  In  two  vols.,  of  over  1000  pages  each.  $12.00 


12 
CLAY  (CHARLES),  M.  D. 

Fellow  of  the  London  Obstetrical  Society,  &d 

THE  COMPLETE  HAND-BOOK  OF  OBSTETRIC  SURGERY, 

or,  Short  Rules  of  Practice  in  Every  Emergency,  from  the  Simplest  to 
the  most  Formidable  Operations  in  the  Practice  of  Surgery.  First 
American  from  the  Third  London  Edition.  With  numerous  Illustra- 
tions. In  one  volume.  $2.00 

CHAMBERS  (THOMAS  K.),  M.  D., 

LECTUR'ES,  CHIEFLY  CLINICAL.     Illustrative  of  a^  Restorative 

System  of  Medicine. 

CORMACK  (SIR  JOHN  ^SE),^  B.,  F.  R.  S.  E.,  M.  D. 

Edinburgh  and  Paris,  Fellow  Royal  College  of  Physicians,  Physician  to  \he  Hertford  British  Hospital,  Paris,  &c. 

CLINICAL  STUDIES,  Illustrated  by  Cases  observed  in  Hospital  and 
Private  Practice.  With  Illustrative  Plates.  2  Volumes.  Octavo.  $5.00 

COBBOLD  (T.  SPENCER),  M.  D.,  F.  R.  S. 

PARASITES :  A  Treatise  on  the  Entozoa  of  Man  and  Animals ; 
including  some  Account  of  the  Ectozoa.  With  85  Engravings.  Oc- 
tavo. Price  .  .  .  .  .  .  .  .  .  $5.00 

CLEAVELAND  (c.  H.),  M.D., 

Member  of  the  American  Medical  Association,  &c. 

A  PRONOUNCING  MEDICAL  LEXICON.    Containing  the  Cor- 
rect Pronunciation  and  Definition  of  Terms  used  in  Medicine  and  the 
Collateral  Sciences.     Improved  Edition,  Cloth,     $1.00;  Tucks,    $1.25 
This  work  is  not  only  a  Lexicon  of  all  the  words  in  common  use  in  Medicine,  but  it  is 
also  a  Pronouncing  Dictionary,  a  feature  of  great  value  to  Medical  Students.    To  the  Dis- 
penser it  will  prove  an  excellent  aid,  and  also  to  the  Pharmaceutical  Student.     It  has  received 
strong  commendation  both  from  the  Medical  Press  and  from  the  profession. 

COLES  (OAKLEY),  D.D.S. 

Dental  Surgeon  to  the  Hospital  for  Diseases  of  the  Throat,  Sic. 

A  MANUAL  OF  DENTAL  MECHANICS.  Containing  much 
information  of  a  Practical  Nature  for  Practitioners  and  Students. 

INCLUDING 

The  Preparation  of  the  Mouth  for  Artificial  Teeth,  on  Taking  Impressions,  Various 
Modes  of  Applying  Heat  in  the  Laboratory,  Casting  in  Plaster  of  Paris  and  Metal, 
Precious  Metals  used  in  Dentistry,  Making  Gold  Plates,  Various  Forms  of  Porcelain 
used  in  Mechanical  Dentistry,  Pivot  Teeth,  Choosing  and  Adjusting  Mineral  Teeth,  the 
Vulcanite  Base,  the  Celluloid  Base,  Treatment  of  Deformities  of  the  Mouth,  Receipts 
for  Making  Gold  Plate  and  Solder,  etc.,  etc. 
With  140  Illustrations.  Price  .  .  $2.00 

SAME  AUTHOR. 

ON  DEFORMITIES  OF  THE  MOUTH,  CONGENITAL  AND 
ACQUIRED,  with  their  Mechanical  Treatment.  Second  Edition,  Re- 
vised and  Enlarged.  With  Illustrations.  Price,  . 

DOMVILLE  (EDWARD  j.),  M.  D. 

A  MANUAL  FOR  HOSPITAL  NURSES  and  Others  engaged  in 
Attending  the  Sick.  i2mo.  Price  .  .  .  .  .  gi.oo 


13 
CLARK  (F.  LE  GROS),  F.  R.  S., 

Senior  Surgeon  to  St.  Thomas's  Hospital. 

OUTLINES  OF  SURGERY  AND  SURGICAL   PATHOLOGY, 

including  the  Diagnosis  and  Treatment  'of  Obscure  and  Urgent  Cases, 
and  the  Surgical  Anatomy  of  some  Important  Structures  and  Regions. 
Assisted  by  W.  W.  WAGSTAFFE,  F.  R.  C.  S.,  Resident  Assistant-Surgeon 
of,  and  Joint  Lecturer  on  Anatomy  at,  St.  Thomas's  Hospital.  Second 
Edition,  Revised  and  Enlarged.  Price  .  .  .  .  $2.00 

COTTLE  (E.  WYNDHAM),  M.  A...  F.  R.  C.  S.,  &c. 

THE  HAIR  IN  HEALTH  AND  DISEASE.  Partly  from  Notes 
by  the  late  GEORGE  NAYLER,  F.  R.  C.  S.,  Surgeon  to  the  Hospital  for 
Diseases  of  the  Skin,  &c.  i8mo.  Cloth.  Price  .  .  $0.75 

CURLING  (T.  B.),  F.  R.  S., 

Consulting  Surgeon  to  the  London  Hospital,  &c. 

A  PRACTICAL  TREATISE  ON  THE  DISEASES  OF  THE 
TESTIS  AND  OF  THE  SPERMATIC  CORD  AND  SCROTUM. 

Fourth  Revised  and  Enlarged  Edition.     Octavo.     Price.         .     $5.50 

BY  SAME  AUTHOR. 

OBSERVATIONS  ON  DISEASES  OF  THE   RECTUM.  With 

Illustrations.     Fourth  Edition,  Revised  and  Enlarged.    Octavo.  Cloth. 

Price     ...........  $2.75 

CAZEAUX  (P.),  M.  D., 

Adjunct  Professor  of  the  Faculty  of  Medicine,  Paris,  etc. 

A  THEORETICAL  AND  PRACTICAL  TREATISE  ON  MIDWIFERY, 
including  the  Diseases  of  Pregnancy  and  Parturition.     Translated  from 
the  Seventh  French  Edition,  Revised,  Greatly  Enlarged,  and  Improved, 
by  S.  TARNIER,  Clinical  Chief  of  the  Lying-in  Hospital,  Paris,  etc., 
with  numerous  Lithographic  and  other  Illustrations.     Price,  in  Cloth, 
$6.00;  in  Leather         ........      $7-oo 

M.  Cazeaux's  Great  Work  on  Obstetrics  has  become  classical  in  its  character,  and  almost 
an  Encyclopaedia  in  its  fulness.  Written  expressly  for  the  use  of  students  of  medicine,  its 
teachings  are  plain  and  explicit,  presenting  a  condensed  summary  of  the  leading  principles 
established  by  the  masters  of  the  obstetric  art,  and  such  clear,  practical  directions  for  the 
management  of  the  pregnant,  parturient,  and  puerperal  states,  as  have  been  sanctioned  by 
the  most  authoritative  practitioners,  and  confirmed  by  the  author's  own  experience. 

DOBELL  (HORACE),  M.  D., 

Senior  Physician  to  the  Hospital. 

WINTER  COUGH  (CATARRH,  BRONCHITIS,  EMPHYSEMA, 

ASTHMA).  Lectures  Delivered  at  the  Royal  Hospital  for  Diseases  of 
the  Chest.  The  Third  Enlarged  Edition,  with  Colored  Plates.  Octavo. 
Price .  $3.50 

BY  SAME  AUTHOR. 

ON  LOSS  OF  WEIGHT,  BLOOD-SPITTING,  AND  LUNG 
DISEASE.  With  a  Colored  Frontispiece  of  the  Lung,  a  Tabular  Map, 
&c.,  &c.  Octavo.  Cloth.  Price $3-25 


14 
DIXON  (JAMES),  F.  R.  C.  S. 

Surgeon  to  the  Royal  London  Ophthalmic  Hospital,  &c. 

A  GUIDE  TO  THE  PRACTICAL  STUDY  OF  DISEASES  OF 
THE  EYE,  with  an  Outline  of  their  Medical  and  Operative  Treatment, 
with  Test  Types  and  Illustrations.  Third  Edition,  thoroughly  Revised, 
and  a  great  portion  Rewritten.  Price  .  .  .  .  .  $2.00 

Mr.  Dixon's  book  is  essentially  a  practical  one,  written  by  an  observant  author,  who  brings 
to  his  special  subject  a  sound  knowledge  of  general  Medicine  and  Surgery. — Dublin  Quarte  fly 

DILLNBERGER  (DR.  EMIL). 

A  HANDY-BOOK  OF  THE  TREATMENT  OF  WOMEN  AND 
CHILDREN'S  DISEASES,  according  to  the  Vienna  Medical  School 
Part  I.  The  Diseases  of  Women.  Part  II.  The  Diseases  of  Children. 
Translated  from  the  Second  German  Edition,  by  P.  NICOL,  M.  D. 
Price $i-5° 

Many  practitioners  will  be  glad  to  possess  this  little  manual,  which  gives  a  large  mas* 
of  practical  hints  on  the  treatment  of  diseases  which  probably  make  up  the  larger  half  oi 
everv-day  practice.  The  translation  is  well  made,  and  explanations  of  reference  to  German 
medicinal  preparations  are  given  with  proper  fulness.  —  The  Practitioner. 

DUNGLISON  (RICHARD  j.),  M.  D. 

THE  PRACTITIONER'S  REFERENCE  BOOK.  Containing 
Therapeutic  and  Practical  Hints,  Dietetic  Rules  and  Precepts,  and 
other  General  Information  Useful  to  the  Physician,  Pharmacist,  and 
Student.  Octavo.  Cloth.  Price  .  .  .  .  $3-5° 

DUCHENNE  (DR.  G.  B.). 

LOCALIZED    ELECTRIZATION    AND    ITS    APPLICATION 
TO  PATHOLOGY  AND   THERAPEUTICS.     Translated  by  HER- 
BERT TIBBITS,  M.D.     With  Ninety-two  Illustrations.     Price     .     $3.00 
Duchenne's  great  work  is  not  only  a  well-nigh  exhaustive  treatise  on  the  medical  uses  of 
Electricity,  but  it  is  also  an  elaborate  exposition  of  the  different  diseases  in  which  Electric- 
ity has  proved  to  be  of  value  as  a  therapeutic  and  diagnostic  agent. 

PART  II.,  illustrated  by  chromo-l'thographs  and  numerous  wood-cuts,  is  preparing. 

DURKEE  (SILAS),  M.D., 

Fellow  of  the  Massachusetts  Medical  Society,  &.c, 

GONORRHCEA  AND  SYPHILIS.  The  Sixth  Edition,  Revised 
and  Enlarged,  with  Portraits  and  Eight  Colored  Illustrations.  Octavo. 

Price .     $3.50 

Dr.  Durkee's  work  impresses  the  reader  in  favor  of  the  author  by  its  general  tone,  the 
thorough  honesty  everywhere  evinced,  the  skill  with  which  the  book  is  arranged,  the  man- 
ner in  which  the  facts  are  cited,  the  clever  way  in  which  the  author's  experience  is  brought 
in,  the  lucidity  of  the  reasoning,  and  the  care  with  which  the  therapeutics  of  venereal  coin 
plaints  are  treated. — Lancet. 

DRUITT  (ROBERT),  F.R.C.S. 

THE  SURGEON'S  VADE-MECUM.  A  Manual  of  Modern  Sur- 
gery. The  Eleventh  Revised  and  Enlarged  Edition,  with  369  Illus- 
trations. Price  .  SS-oo 


15 
DALBY  (w.  B.),  F.R.  C.S., 

Aural  Surgeon  to  St.  George's  Hospital. 

LECTURES  ON  THE  DISEASES  AND  INJURIES  OF  THE 
EAR.  Delivered  at  St.  George's  Hospital.  With  Illustrations. 
Price $1.50 

We  cordially  recommend  this  admirable  volume  by  Mr.  Dalby  as  a  trustworthy  guide  in 
the  treatment  of  the  affections  of  the  ear.  The  book  is  moderate  in  price,  beautifully  illus- 
trated by  wood-cuts,  and  got  up  in  the  best  style.  —  Glasgow  Medical  Journal. 

DAY  (WILLIAM  HENRY),  M.  D., 

Physician  to  the  Samaritan  Hospital  for  Women  and  Children,  &c. 

HEADACHES,  THEIR  NATURE,  CAUSES,  AND  TREAT- 
MENT. Second  Edition.  121110.  Cloth.  Price  .  .  $2.00 

DUNGLISON  (ROBLEY),  M.  D., 

Late  Professor  of  Institutes  of  Medicine,  &c.,  in  the  Jefferson  Medical  College. 

A  HISTORY  OF  MEDICINE,  from  the  Earliest  Ages  to  the  Com- 
mencement of  the  Nineteenth  Century.  Edited  by  his  son,  RICHARD 
J.  DUNGLISON,  M.  D.  .  .  .  .  .  .  .  $2.50 

ELLIS  (EDWARD),  M.  D., 

Physician  to  the  Victoria  Hospital  for  Sick  Children,  &c. 

A  PRACTICAL  MANUAL  OF  THE  DISEASES  OF  CHIL- 
DREN, with  a  Formulary.  Third  Enlarged  Edition,  Revised  and 
Improved.  One  volume.  .  .  .  .  .  .  .  £2.00 

The  AUTHOR,  in  issuing  this  new  edition  of  his  book,  says :  "I  have  very  carefully  revised 
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inutiily  increasing  the  bulk  of  the  volume." 

FOTHERGILL  (j.  MILNER),  M.  D., 

Assistant  Physician  to  City  of  London  Hospital  for  Diseases  of  the  Chest,  &c. 

THE  HEART,  ITS  DISEASES  AND  THEIR  TREATMENT, 

including  the  Gouty  Heart.  Second  Edition,  Entirely  Rewritten  and 
Enlarged,  with  Two  Full-Page  Lithographic  Plates  and  Forty  other 
Illustrations.  Octavo.  Price  ......  $3.50 

"  Dr.  Fothergill's  remarks  on  rest,  on  proper  blood  nutrition  in  Heart  Disease,  in  the 
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ing the  pathology  of  Heart  Disease,  he  has  earnestly  kept  in  view  the  best  means  of  mitigat- 
ing suffering  and  of  prolonging  life."  —  Lancet. 

FOX  (CORNELIUS  B.),  M.  D. 

SANITARY  EXAMINATIONS  of  Water,  Air,  and  Food.  94  En- 
gravings. 8vo.  Price $4.00 

FOX  (TILBURY),  M.  D.,  F.  R.  C.  P. 

Physician  to  the  Department  for  Skin  Diseases  in  University  College  Hospital. 

ATLAS  OF  SKIN  DISEASES.  Consisting  of  a  Series  of  Colored 
Illustrations,  in  Monthly  Parts,  together  with  Descriptive  Text  and 
Notes  upon  Treatment ;  each  Part  containing  Four  Plates,  reproduced  by 
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Original  Sources.  Now  Complete  in  18  Parts.  Price,  per  Part,  $2.00  ; 
or  in  one  large  Folio  volume,  bound  in  cloth.  Price  .  .  $30.00 


16 

FENNER  (c.  s.),  M.  D.,  &c. 

VISION:  ITS  OPTICAL  DEFECTS,  and  the  Adaptation  of  Spec- 
tacles ;  embracing  Physical  Optics,  Physiological  Optics,  Errors  of  Re- 
fraction and  Defects  of  Accommodation,  or  Optical  Defects  of  the  Eye. 
With  74  Illustrations.  Selections  from  the  Test  Types  of  Jaeger  and 
Snellen,  etc.  Octavo.  Price $3-5° 

FOSTER  (BALTHAZAR),  M.D., 

Professor  of  Medicine  in  Queen's  College. 

LECTURES  AND  ESSAYS  ON  CLINICAL  MEDICINE.  Re- 
vised and  Enlarged  by  the  Author.  With  Engravings.  Octavo. 
Price $3-°° 

FRANKLAND  (E.),  M.  D.,  F.  R.  S.,  &c. 

HOW  TO  TEACH  CHEMISTRY,  being  the  substance  of  Six 
Lectures  to  Science  Teachers.  Reported,  with  the  Author's  sanction, 
by  G.  George  Chaloner,  F.  C.  S.,  &c.  With  Illustrations  .  $1.25 

FULTON  (;.),  M.  D., 

Professor  of  Physiology,  Trinity  Medical  College,  Toronto, 

A  TEXT-BOOK  OF  PHYSIOLOGY.  Second  Edition,  Revised 
and  Enlarged.  With  numerous  Illustrations.  Octavo.  Price  $4.00 

FLINT  (AUSTIN),  M.D., 

Professor  of  the  Principles  and  Practice  of  Medicine,  &.C.,  Bellevue  Hospital  College,  New  York. 

CLINICAL  REPORTS  ON  CONTINUED  FEVER.  Based  on 
an  Analysis  of  One  Hundred  and  Sixty-four  Cases,  with  Remarks  on 
the  Management  of  Continued  Fever;  the  Identity  of  Typhus  and 
Typhoid  Fever;  Diagnosis,  &c.,  &c.  Octavo.  Price  .  .  $2.00 

GANT  (FREDERICK  j.),  F.  R.  C.  S., 

Assisted  by  Drs.  Morrell   Mackenzie,  Barnes,  Erasmus  Wilson,  and  other  Specialists. 

THE  SCIENCE  AND  PRACTICE  OF  SURGERY.  Second 
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DISEASES  OF  THE  BLADDER,  PROSTATE  GLAND,  AND 

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lustrations. Now  Ready.  Price  .  .  .  .  .  $3- 50 

GODLEE  (R.  j.),  M.  D., 

Assistant-Surgeon  University  College  Hospital. 

AN  ATLAS  OF  HUMAN  ANATOMY.  Illustrating  the  Anatomy 
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/ 

GROSS  (SAMUEL  D.),  M.  D., 

Professor  of  Surgery  in  the  Jefferson  Medical  College,  Philadelphia,  etc. 

/AMERICAN  MEDICAL  BIOGRAPHY  OF  THE  NINETEENTH 
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GREENHOW  (E.  HEADLAM).  M.  D., 

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ON  CHRONIC  BRONCHITIS,  Especially  as  Connected  with  Gout, 
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ADDISON'S    DISEASE.      Illustrated  by   numerous  Cases  and  5 

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GOWERS  (w.  R.),  M.  D.,  F.  R.  C.  P., 

Assistant  Professor  of  Clinical  Medicine  in  University  College, 

A  MANUAL  AND  ATLAS  OF  MEDICAL  OPHTHALMO- 
SCOPY.  With  16  Colored,  Autotype,  and  Lithographic  Plates,  and 
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GALLABIN  (ALFRED  LEWIS),  M.  D., 

Assistant  Obstetric  Physician  and  Joint  Lecturer  on  Midwifery,  Guy's  Hospital,  &c. 

THE  STUDENT'S  GUIDE  TO  THE  DISEASES  OF  WOMEN". 
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HIGGINS  (CHAMPS),  F.  R.  C.  S., 

Ophthalmic  Surgeon,  Guy's  Hospital,  die, 

HINTS  ON  OPHTHALMIC  OUT-PATIENT  PRACTICE.  Sec- 
ond Edition.  i6mo.  Cloth.  Price  ....  60  cts. 

HUNTER  (CHARLES). 

MECHANICAL  DENTISTRY.  A  Practical  Treatise  on  the  Con- 
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Receipts,  &c.  100  Illustrations.  Price  ....  $2.25 

HEATH   (CHRISTOPHER),  F.  R.  C.  S., 

Surgeon  to  University  Colege  Hospital  and  Holme  Professor  of  Clinical  Surgery  in  Univers  *y  College. 

OPERATIVE  SURGERY.  Elegantly  Illustrated  by  20  Large  Col- 
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HEWITT  (GRAIIY),  M.  D., 

Physician  to  the  British  Lying-in  Hospital,  and  Lecturer  on  Diseases  of  Women  and  Children,  &c. 

THE  DIAGNOSIS,  PATHOLOGY,  AND  TREATMENT  OF 
DISEASES  OF  WOMEN,  including  the  Diagnosis  of  Pregnancy. 
Founded  on  a  Course  of  Lectures  delivered  at  St.  Mary's  Hospital 
Medical  School.  The  Third  Edition,  Revised  and  Enlarged,  with 
new  Illustrations.  Octavo.  Price  in  Cloth  ...  .  ^4.00 

"         Leather     .         .         .  5.00 

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18 
HILLIER  (THOMAS),  M.  D., 

Physician  to  the  Hospital  for  Sick  Children,  &c 

A  CLINICAL  TREATISE  ON  THE  DISEASES  OF  CHILDREN. 
Octavo.  Price  .........  $2.00 

HANDY'S  TEXT-BOOK  OF  ANATOMY  and  Guide  to  Dissec- 
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HOLDEN  (LUTHER),  RR.C.S. 
HUMAN    OSTEOLOGY,    comprising  a  Description  of  the  Bones 

with   Delineations    of  the   Attachments   of  the    Muscles,    &c.     With 

numerous  Illustrations.     Fifth  Edition,  carefully  Revised.    Price,  $5.50 
HOLDEN'S  MANUAL  OF  DISSECTIONS  OF  THE  HUMAN 

BODY.     Fourth  London  Edition.     With  Illustrations.     Price 
LANDMARKS,  MEDICAL  AND  SURGICAL.     Second  Edition, 

Revised  and  Enlarged.     Price     .         .         .         .         .         .         $1.00 

HARRIS  (CHAPIN  A.),  M.  D.,  D.  D.  S. 

Late  President  of  and  Professor  of  the  Principles  and  Practice  of  Dental  Surgery  in  the  Baltimore  College,  &c, 

THE  PRINCIPLES  AND  PRACTICE  OF  DENTISTRY.     Tenth 

Revised  Edition.  .  In  great  part  rewritten,  rearranged,  and  with  many 
new  and  important  Illustrations.  Including — i.  Dental  Anatomy  and 
Physiology.  2.  Dental  Pathology  and  Therapeutics.  3.  Dental  Sur- 
gery. 4.  Dental  Mechanics.  Edited  by  P.  H.  AUSTEN,  M.D.,  Pro- 
fessor of  Dental  Science  and  Mechanism  in  the  Baltimore  College  of 
Dental  Surgery.  With  nearly  400  Illustrations,  including  many  new 
ones  made  especially  for  this  edition.  Royal  octavo.  Price,  in  cloth, 
$6.50;  in  leather  ........  $7.50 

This  new  edition  of  Dr.  Harris's  work  has  been  thoroughly  revised  in  all  its  parts — more 
so  than  any  previous  edition.  So  great  have  been  the  advances  in  many  branches  of  dentistry, 
that  it  was  found  necessary  to  rewrite  the  articles  or  subjects,  and  this  has  befcn  done  in  the 
most  efficient  manner  by  Professor  Austen,  for  many  years  an  associate  and  friend  of  Dr. 
Ptarris.  assisted  by  Professor  Gorgas  and  Thomas  S.  Latimer,  M.D.  The  publishers  feel 
assured  that  it  will  nosv  be  found  the  most  complete  text-book  for  the  student  and  guide  lor 
the  practitioner  in  the  English  language. 

SAME  AUTHOR. 

A  DICTIONARY  OF  MEDICAL  TERMINOLOGY,  DENTAL 
SURGERY,  AND  THE  COLLATERAL  SCIENCES.  Fourth  Edition, 
.Carefully  Revised  and  Enlarged,  by  FERDINAND  J.   S.  GORGAS,  M.  D., 
D.D.S.,  Professor  of  Dental  Surgery  in  the  Baltimore  College,  &c.,  &c. 
Royal  octavo.     Price,  in  cloth,  $6.50;  in  leather          .         .         $7-5° 
The  many  advances  in  Dental  Science  rendered  it  necessary  that  this  edition  should  be 
thoroughly  revised,  which  has  been  done  in  the  most  satisfactory  manner  by  Professor  Gorgas, 
Dr.  Harris's  successor  in  the  Baltimore  Dental  College,  he  having  added  nearly  three  thou- 
sand new  words,  besides  making  many  additions  and  corrections.     The  doses  of  the  more 
prominent  medicinal  agents  have  also  been  added,  and  in  every  way  the  book  lias  been  greatly 
improved,  and  its  value  enhanced  as  a  work  of  reference. 

HABERSHON  (s.  o.),  M.  D.,  F.  R.  C.  P., 

Senior  Physician,  Guy's  Hospital. 

ON  DISEASES  OF  THE  ABDOMEN,  STOMACH,  and  Other 
Parts  of  the  Alimentary  Canal.  Third  London  Edition.  Price,  $5.00 

ON  DISEASES  OF  THE  STOMACH  :  The  Varieties  of  Dyspepsia, 
their  Diagnosis  and  Treatment.  Third  Edition.  Octavo  .  $1.75 


19 

HARDWICH  AND  DAWSON. 

HARDWICH'S  MANUAL  OF  PHOTOGRAPHIC  CHEMISTRY. 

With  Engravings.     Eighth  Edition.      Edited  and  Rearranged  by  G. 
DAWSON,  Lecturer  on  Photography,  &c.,  &c.     121110    .          .          $2.00 

HARLAN  (GEORGE  c.),  M.  D., 

Surgeon  to  Wills'  Eye  Hospital,  &c. 

EYESIGHT,  AND  HOW  TO  CARE  FOR  IT.  (Vol.  IV.,  Amer- 
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HEADLAND  (F.  w.),  M.  D., 

Fellow  of  the  Royal  College  of  Physicians,  S.C.,  &c. 

ON  THE  ACTION  OF  MEDICINES  IN  THE  SYSTEM.  Sixth 
American  from  the  Fourth  London  Edition.  Revised  and  Enlarged. 
Octavo.  Price  .........  $3.00 

Dr.  Headland's  work  gives  the  only  scientific  and  satisfactory  view  of  the  action  of  medi- 
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and  inferences  almost  as  indisputable  as  demonstrations.  It  is  truly  a  great  scientific  work 
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has  received  the  approbation  of  the  Medical  Press,  both  in  this  country  and  in  Europe,  and 
is  pronounced  by  them  to  be  the  most  original  and  practically  useful  work  that  has  been 
issued  for  many  yeara. 

HOFF  (o.),  M.  D. 

ON  H^EMATURIA  as  a  Symptom  of  Diseases  of  the  Genito-Uri- 

nary  Organs.     Illustrated.      121110.     Cloth.     ....     $0.75 

HEATH  (CHRISTOPHER),  F.R.C.S., 

Surgeon  to  University  College  Hospital,  &c. 

INJURIES  AND  DISEASES  OF  THE  JAWS.  The  Jacksonian 
Prize  Essay  of  the  Royal  College  of  Surgeons  of  England,  1867.  Sec- 
ond Edition,  Revised,  with  over  150  Illustrations.  Octavo.  Price, 

$4-25 

SAME  AUTHOR. 

A  MANUAL  OF  MINOR  SURGERY  AND  BANDAGING,  for 
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a  Formulae  and  Numerous  Illustrations.  i6mo.  Price  .  $2.00 

A  GUIDE  TO  SURGICAL  DIAGNOSIS,  for  Practitioners  and 
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HAYDEN  (THOMAS),  M.  D., 

Fellow  of  the  King  and  Queen's  College  of  Physicians,  &c.,  &c. 

THE  DISEASES  OF  THE  HEART  AND  AORTA.  With  81 
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HUFELAND  (c.  w.),  M.D. 

THE  ART  OF  PROLONGING  LIFE.     Edited  by  ERASMUS  WiL-f 
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HAY  (THOMAS),  M.  D., 

•  HISTORY  OF  A  CASE  OF  RECURRING  SARCOMATOUS 
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20 
HEWSON  (ADDINELL,)  M.  D. 

Attending  Surgeon  Pennsylvania  Hospital,  &c. 

EARTH  AS  A  TOPICAL  APPLICATION  IN  SURGERY. 
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HUTCHINSON  (JONATHAN),  F.  R.  C  S. 

Senior  Surgeon  to  the  London  Hospital. 

ILLUSTRATIONS  OF  CLINICAL  SURGERY.  Consisting  of 
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^rospectuses  furnished  upon  application. 


HODGE  (HUGH  L.),  M.  D. 

Emeritus  Professor  In  the  University  of  Pennsylvania. 

HODGE  ON  FCETICIDE,  OR  CRIMINAL  ABORTION. 
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HOLDEN  (EDGAR),  A.  M.,  M.  D., 

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HOOD  (PETER),  M.  D., 

President  West  Hart's  Medic..!  Association,  &c. 

A  TREATISE  ON  GOUT,  RHEUMATISM,  AND  THE  ALLIED 

AFFECTIONS.  Their  Treatment:,  Complications,  and  Prevention. 
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JONES  (H.  MACNAUGHTON),  M.  D.,  M.  CH. 
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JONES  (T.  WHARTON),  F.R.S, 

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JONES,  SIEVEKING,  AND  PAYNE. 

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EDWARD  H.  SIEVEKING,  M.D. ,  F.R.C.P.,  Physician  to  St. Mary's  Hos- 
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21 
JAMES  (PROSSER),  M.  D.,  M.  R.  C.  P., 

Physician  to  Throat  Hospital. 

SORE  THROAT:  Its  Nature.Varieties,  and  Treatment,  and  its  Con- 
nection with  other  Diseases.  Fourth  Edition.  Colored  Plates,  121110. 
Price $2.00 

JONES'  AURAL  ATLAS. 

AN  ATLAS  OF  DISEASES  OF  THE  MEMBRANA  TYMPANI. 
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KIDD  (jo.sEPH)JVrD.,  M.  R.  C.  S. 

THE  LAWS  OF  THERAPEUTICS,  or  The  Science  and  Art  of 
Medicine.  i2mo.  Cloth.  Price  .  .  .  .  .  $1.25 

LONGLEY"(ELIAS). 

Author  of  a  "  Pronouncing  Vocabul  ry  of  Geographical  ;;nd  Personal  Names,"  &c. 

STUDENT'S  POCKET  MEDICAL  LEXICON.  Giving  the  Cor- 
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use  in  Medicine  and  the  Collateral  Sciences.  The  Pronunciation  being 
plainly  represented  in  the  American  Phonetic  Alphabet.  With  an 
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This  is  an  entirely  new  Medical  Dictionary,  containing  some  300  compactly  printed 
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preparation  of  similar  works,  assisted  by  the  Professors  of  Chemistry  and  of  Botany  in  one 
of  our  leading  Medical  Colleges.  It  contains  all  medical  terms  in  common  use,  with  their 
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It  is  essentially  new  in  many  of  its  features,  and  fully  brought  up  to  the  present  state  of 
medical  science. 

LAWSON  (^EORG"E),  F.R.C.S., 

Surgeon  to  the  Royal  London  Ophthalmic  Hospital. 

DISEASES  AND  INJURIES  OF  THE  EYE,  THEIR  MEDICAL 
AND  SURGICAL  TREATMENT.  Containing  a  Formulary,  Test 
Types,  and  Numerous  Illustrations.  Price  ....  $2.00 

LEBER  &  ROTTENSTEIN  (DRS.). 

DENTAL  CARIES  AND  ITS  CAUSES.  An  Investigation  into 
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THOMAS  H.  CHANDLER,  D.M.D  ,  Professor  of  Mechanical  Dentistry  in 
the  Dental  School  of  Harvard  University.  With  Illustrations.  Octavo. 
Price  .  ^.25 

LEARED  (ARTHUR),  M.D.,  F.R.C.P. 

IMPERFECT  DIGESTION:  ITS  CAUSES  AND  TREATMENT. 

The  Sixth  Edition,  Revised  and  Enlarged.       .         .         .         .     $1.50 

KOLLMEYER  (A.  H.),  A.  M.,  M.  D. 

Professor  of  Materia  Medica  and  Therapeutics,  Montreal  College. 

CHEMIA  COARTATA  ;  or,  The  Key  to  Modern  Chemistry.  With 
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22 
LEWIN   (DR.  GEORGE). 

Professor  at  the  Fr.-Wilh.  University)  and  Surgeon-in-Chief  of  the  Syphilitic  Wards  and  Skin  Diseases  of 

the  Charity  Hospital,  Berlin. 

THE  TREATMENT  OF  SYPHILIS  by  Subcutaneous  Sublimate 
Injections.  With  a  Lithographic  Plate  illustrating  the  Mode  and  Proper 
Place  of  administering  the  Injections,  and  of  the  Syringe  used  for  the 
purpose.  Translated  by  CARL  PRCEGLER,  M.D.,  late  Surgeon  in  the 
Prussian  Service,  and  E.  H.  GALE,  M.D.,  late  Surgeon  in  the  United 
•  States  Army.  Price  .  .  .  .  .  .  .  .  $1.50' 

MASON  (FRANCIS),  F.  R.  C.  S., 

Surgeon  and  Lecturer  on  Anatomy  at  St.  Thomas'  Hospital,  &c. 

THE  SURGERY  OF  THE  FACE.  With  100  Illustrations,  En- 
graved on  Wood,  of  Various  Operations  Performed.  Octavo.  Cloth. 

Price,  $2.25 

MORRIS  "(HENRY),  F.  R.  C.  S. 

THE  ANATOMY  OF  THE  JOINTS  OF  MAN.  Comprising  a 
Description  of  the  Ligaments,  Cartilages,  and  Synovial  Membranes  ;  of 
the  Articular  Parts  of  Bones,  &c.  Illustrated  by  44  Large  Plates  and 
Numerous  Figures,  many  of  which  are  Colored.  Octavo.  Price,  $5.50 

MACNAMARA  (c.). 

Surgeon  to  the  Ophthalmic  Hospital,  and  Professor  of  Ophthalmic  Medicine  in  the  Medical  College,  Calcutta. 

MANUAL  OF  THE  DISEASES  OF  THE  EYE.  The  Third 
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Plates,  Diagrams  of  the  Eye,  many  Illustrations  on  Wood,  Snellen's 
Test  Types,  &c.,  &c.  Price  .  .  .  .  .  .  $4.00 

MARSH  (SYLVESTER). 

SECTION-CUTTING.  A  Practical  Guide  to  the  Preparation  and 
Mounting  of  Sections  for  the  Microscope  —  special  prominence  being 
given  to  the  subject  of  Animal  Sections.  With  Illustrations.  Cloth. 

Price,  $0.75 

MACKENZIE  (MORELL).  M.  D  , 

Physician  to  the  Hospital  for  Diseases  of  the  Throat,  &c. 

GROWTHS  IN  THE  LARYNX.  Their  History,  Causes,  Symp- 
toms, &c.  With  Reports  and  Analysis  of  One  Hundred  Cases.  With 
Colored  and  other  Illustrations.  Price  .....  $2.00 

OTHER    WORKS   BY  THE  SAME  AUTHOR. 

THE  LARYNGOSCOPE  IN  THROAT  DISEASES.  With  an 
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lustrations. Price  ........ 

THE  DISEASES  OF  THE  THROAT  AND  NOSE.  Including 
The  Pharynx,  The  Larynx,  Trachea,  CE^ophagus,  Nose,  Neck,  &c. 
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gles, &c.,  &c.  Fourth  Edition.  Preparing. 


23 

MEIGS  AND  PEPPER. 

A  PRACTICAL  TREATISE  ON  THE   DISEASES  OF  CHIL- 
DREN.    By  J.  FORSYTH  MEIGS,  M.D.,  Fellow  of  the  College  of  Physi- 
cians of  Philadelphia,  &c.,  &c.,  and  WILLIAM  PEPPER,  M.D.,  Physician 
to  the  Philadelphia  Hospital,  &c.     Sixth  Edition,  thoroughly  Revised 
and  greatly  Enlarged,  forming  a  Royal  Octavo  Volume  of  over  1000 
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MEARS  (j.  EWING),  M.  D., 

Demonstrator  of  Surgery  in  Jefferson  Medical  College,  &c. 

PRACTICAL  SURGERY :  Including  Surgical  Dressings,  Bandag- 
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MENDENHALL  (GEORGE),  M.D., 

Professor  of  Obstetrics  in  the  Medical  College  of  Ohio,  &.c. 

MEDICAL  STUDENT'S  VADE  MECUM.  A  Compendium  of 
Anatomy,  Physiology,  Chemistry,  the  Practice  of  Medicine,  Surgery, 
Obstetrics,  Diseases  of  the  Skin,  Materia  Medica,  Pharmacy,  Poisons, 
&c.,  &c.  Eleventh  Edition,  Revised  and  Enlarged,  with  224  Illustra- 
tions. In  cloth  .........  $2.00 

MAXSON  (EDWIN  R.),  M.D., 

Formerly  Lecturer  on  the  Practice  of  Medicine  in  the  Geneva  Medical  College,  &c. 

THE  PRACTICE  OF  MEDICINE.      ...  .     $3.00 

MARSHALL  (JOHN),  F.R.S., 

Professor  of  Surgery,  University  College,  London. 

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No.  4.  The  Organs  of  Circulation. 

No.  5.  The  Lymphatics  or  Absorbents. 

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No.    7.  The  Brain  and  Nerves. 

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of  the- Voice.     Plate  1. 
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Textures.    Plate  1. 
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Textures.    Plate  2. 


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An  Explanatory  Key  to  the  Diagram.     Price         .         .         .         .  $0.50 

MADDEN  (T.  M.),  M.  D. 

Author  of  "  Climatology  and  the  Use  of  Mineral  Waters." 

THE  HEALTH  RESORTS  OF  EUROPE  AND  AFRICA  for  the 
Treatment  of  Chronic  Diseases.  A  Hand -Book  the  result  of  the 
Author's  own  Observations  during  several  years  of  Health-Travel  in 
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Price  ,         .  . S£?.CQ 


24 
MAUNDER  (c.  F.),  F.R.C.S. 

Surgeon  to  the  London  Hospital)  formerly  Demonstrator  of  Anatomy  at  Guy's  Hospital. 

OPERATIVE  SURGERY.  Second  Edition,  with  One  Hundred 
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BY  SAME  AUTHOR. 

SURGERY  OF  THE  ARTERIES,  including  Aneurisms.  Wounds, 
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MAYNE  (R.  G.),  M.  D.,  AND  MAYNE  (j.),  M.  D. 

MEDICAL  VOCABULARY:  An  Explanation  of  all  Names, 
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MAYS  (THOMAS  ;.),  M.  D. 

ON  THE  THERAPEUTIC  FORCES.  An  Effort  to  Consider  the 
Action  of  Medicines  in  the  Light  of  the  Doctrine  of  Conservation  of 
Force.  I2mo.  Cloth.  Price  .  .  .  .  .  .  $1.25 

MARTIN  (JOHNH.). 

Author  of  Microscopic  Objects,  &c. 

A  MANUAL  OF  MICROSCOPIC  MOUNTING.  With  Notes  on 
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dred and  Fifty  Illustrations.  Second  Edition,  Enlarged.  Price,  $2.75 

MEADOWS  (ALFRED),  M.  D. 

Physician  to  the  Hospital  for  Women,  and  to  the  General  Lying-in  Hospital,  &c. 

MANUAL  OF  MIDWIFERY.  A  New  Text-Book.  Including-  the 
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Illustrations  are  numerous  and  well  executed. 

MILLER  (JAMES),  F.  R.  C.  S. 

Professor  of  Surgery  University  of  Edinburgh. 

ALCOHOL,  ITS  PLACE  AND  POWER.  From  the  Nineteenth 
Glasgow  Edition.  121110.  Cloth  flexible.  Price  .  .  .  $0.50 

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MILLER  AND  LIZARS. 

ALCOHOL:  Its  Place  and  Power.  By  JAMES  MILLER,  F.R.S.E.,  late 
Professor  of  Surgery  in  the  University  of  Edinburgh,  &c. — THE  USE 
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Royal  College  of  Surgeons.,  &c.  The  Two  Essays  in  One  Volume. 
I2mo.  ....  gi.oo 


25 

MARSDEN   (ALEXANDER),  M.D. 

A  NEW  AND  SUCCESSFUL  MODE  OF  TREATING  CERTAIN 
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MACDONALD  (j.  D.),  M.  D., 

Deputy  Inspector-General  of  Hospitals,  Assistant  Professor  of  Hygiene,  Army  Medical  School,  &c. 

A  GUIDE  TO  THE  MICROSCOPICAL  EXAMINATION  OF 
DRINKING  WATER.  With  Twenty  Full-page  Lithographic  Plates, 
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NORRIS  (GEORGE  w.),  M.  D., 

Late  Surgeon  to  the  Pennsylvania  Hospital,  &c, 

CONTRIBUTIONS  TO  PRACTICAL  SURGERY,  including 
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OTT  (ISAAC),  M.  D., 

Late  Demonstrator  of  Experimental  Physiology  in  the  University  of  Pennsylvania! 

THE  ACTION  OK  MEDICINES.  With  Twenty-two  Illustrations. 
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OGSTON   (FRANCIS  AND  FRANCIS,  JR.),  M.D. 

Professor  of  Medical  Jurisprudence,  and  Assistant  Professor  in  the  University  of  Aberdeen! 

LECTURES  ON  MEDICAL  JURISPRUDENCE.  With  Copper- 
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26 
PARKES  (EDWARD  A.),  M.  D., 

Professor  of  Military  Hygiene  in  the  Army  Medical  School,  &c, 

A  MANUAL  OF  PRACTICAL  HYGIENE.  The  Eifth  Revised 
and  Enlarged  Edition,  for  Medical  Officers  of  the  Army,  Civil  Medical 
Officers,  Boards  of  Health,  &c.,  &c.  With  many  Illustrations.  One 
Volume  Octavo.  Price  .......  $6.00 

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book  is  devoted  to  the  service  of  the  soldier,  but  is  hardly  less  instructive  to  the  civil  officer 
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scientific  or  general  reader.—  London  Lancet. 

OSGOOD  (HAMILTON),  M.  D., 

Editorial  Staff  Boston  M  dical  and  Surgical  J  urnaL 

WINTER  AND  ITS  DANGERS.  (Vol.  V.,  American  Health 
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PENNSYLVANIA  HOSPITAL  REPORTS. 

EDITED  BY  A  COMMITTEE  OF  THE   HOSPITAL   STAFF. 

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do  much  towards  elevating  the  profession  of  this  country. —  American  Journal  of  Obstetrics. 

PAGET  (JAMES),  F  R.  S., 

Surgeon  to  St.  Bartholomew's  Hospital,  &c. 

SURGICAL  PATHOLOGY.  Lectures  delivered  at  the  Royal  Col- 
lege of  Surgeons  of  England.  Third  London  Edition,  Edited  and 
Revised  by  WILLIAM  TURNER,  M.  D.  With  Numerous  Illustrations. 
Price,  in  cloth,  $7.00;  in  leather  .  .  .  .  .  $8.00 

A  new  and  revised  edition  of  Mr.  Paget's  Classical  Lectures  needs  no  introduction  to  our 
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PEREIRA  (JONATHAN),  M.  D.,  F.  R.  S.,  &c. 
PHYSICIAN'S    PRESCRIPTION    BOOK.     Containing   Lists   of 

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27 
PARSONS  (CHARLES),  M.  D., 

Honorary  Surgeon  to  the  Dover  Convalescent  Homes,  &c,,  &c. 

SEA-AIR  AND  SEA-BATHING.  Their  Influence  on  Health  a 
Practical  Guide  for  the  Use  of  Visitors  at  the  Seaside.  i8mo.  $0.60 

PARKER  (LANGSTON),  F.  R.  C.  S.  L. 

THE  MODERN  TREATMENT  OF    SYPHILITIC  DISEASES. 

Containing  the  Treatment  of  Constitutional  and  Confirmed  Syphilis, 
with  numerous  Cases,  Formulae,  &c.,&c.  Fifth  Edition,  Enlarged.  $4.25 

PRINCE  (DAVID),  M.  D. 

PLASTIC  AND  ORTHOPEDIC  SURGERY.  Containing  i.  A 
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pedic Surgery  up  to  the  Year  1871.  2.  A  New  Classification  and  Brief 
Exposition  of  Plastic  Surgery.  With  numerous  Illustrations.  3.  Ortho- 
pedics: A  Systematic  Work  upon  the  Prevention  and  Cure  of  Deformities. 
With  numerous  Illustrations.  Octavo.  Price  $4.  co 

7r"  T^     ^ 

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SAME  AUTHOR. 
GALVANO-THERAPEUTICS.     A  Revised  reprint  of  A  Report 

made  to  the  Illinois  State  Medical  Society.     With  Illustrations.     Price, 

$1-25 

PIESSE  (G.  w.  SEPTIMUS), 

Analytical  Chemist. 

WHOLE  ART  OF  PERFUMERY.     And  the  Methods  of  Obtaining 

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Practical  Chemist. 

COPPER  MINING  AND  COPPER  ORE.  Containing  a  full  Descrip- 
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Price,  per  dozen     . 

i 


28 
RINDFLEISCH   (DR.  EDWARD). 

Professor  of  Pathological  Anatomy,  University  of  Bonn. 

TEXT-BOOK  OF  PATHOLOGICAL  HISTOLOGY.     An  Intro. 

duction  to  the  Study  of  Pathological  Anatomy.  Translated  frum  the 
German,  by  WM.  C.  KLOMAN,  M.D.,  assisted  by  F.  T.  MILES,  M.D., 
Professor  of  Anatomy,  University  of  Maryland,  &c.,  &c.  Containing 
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tions. Octavo.  Price,  bound  in  Cloth,  .  .  .  .  $5.00 
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This  is  now  confessedly  the  leading  book,  and  the  only  complete  one  on  the  subject  in 
the  English  language.  The  London  Lancet  says  of  it :  "  Rindfleisch's  work  forms  a  mine 
which  no  pathological  writer  or  student  can  afford  to  neglect,  who  desires  to  interpret  aright 
pathological  structural  changes,  and  his  book  is  consequently  well  known  to  readers  of  Ger- 
man medical  literature.  What  makes  it  especially  valuable  is  the  fact  that  it  was  originated, 
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the  book  is  the  result  of  honest  hard  labor.  It  is  admirably  as  well  as  profusely  illustrated, 
furnished  with  a  capital  Index,  and  got  up  in  a  way  that  is  worthy  of  what  must  continue 
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Assistant  Physician  and  Teacher  of  Clinical  Medicine  in  the  University  College  Hospital  j  Assistant  Physician 
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LECTURES   ON   THE  CLINICAL  USES  OF  ELECTRICITY. 

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11 


29 

RADCLIFFE  (CHARLES  BLAND),  M.D., 

Fellow  of  the  Royal  College  of  Physicians  of  London,  &c. 

LECTURES    ON    EPILEPSY,    PAIN,    PARALYSIS,   and   other 

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31 
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33 

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34 
TROUSSEAU  (A.), 

Professor  of  Clinical  Medicine  to  the  Faculty  of  Medicine,  Paris,  &c. 

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35 
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AMERICAN  HEALTH  PRIMERS, 

Edited  by  W.  W.  KEEN,  M.D., 

Fellow  of  the  College  Physicians,  Philadelphia,  Surgeon  to  St.  Mary's  Hospital,  &c. 


It  is  one  of  the  chief  merits  of  the  Medical  Profession  in  modern  times  that  its  members 
are  in  the  fore-front  of  every  movement  to  prevent  disease.  It  is  due  to  them  that  the 
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citizens  of  many  callings.  The  American  Public  Health  Association  and  the  Social  Science 
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sprung  from,  and  still  further  extend  and  reinforce,  the  efforts  to  improve  the  public  health. 

But  the  great  mass  of  the  public  scarcely  recognize  the  importance  of  such  efforts,  or,  if 
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knowledge  does  not  come  by  nature.  In  most  cases,  in  fact,  it  is  a  direct  result  of  the  most 
laborious  research  and  the  highest  skill.  Accordingly,  it  is  the  object  of  this  series  of 
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The  series  is  written  from  the  American  standpoint,  and  with  especial  reference  to  our 
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especially  in  our  large  cities. 

The  subjects  selected  are  of  vital  and  practical  importance  in  every-day  life.  They  are 
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of  the  structure  and  functions  of  the  body.  The  authors  have  been  selected  with  great 
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study,  either  privately  or  as  public  teachers. 

Dr.  W.  W.  Keen  has  undertaken  the  supervision  of  the  series  as  Editor,  but  it  will  be  un- 
derstood that  he  is  not  responsible  for  the  statements  or  opinions  of  the  individual  authors. 

Six  VOLUMES  are  NOW  READY,  others  are  in  Press 

(By  CHAS.  H.  BURNETT,  M.D.,  of  Philada., 

turgeon  in  charge  of  Phila.  Disp.  for  Diseases  of 
the  Ear,  Aurist  to  Presbyterian  Hospital,  etc. 

II     I  nnn  Lifp  and  How  tn  Rparh  It  /ByJ-  G.  RICHARDSON,  M.D.,  of  Philada., 

II.     LOng    LITe,  ana   nOW  TO    neacn   IT.  j     Prof,  of  Hygiene  in  University  of  Penna.,  etc. 

mC««   A!«  r>nrl  C«o   Br.4-1,  :n,i  f  By  JOHN  H.  PACKARD,  M.D.,  of  Philada., 

.  Sea  Air  and  Sea  Bathing.  {  y si,-gt  on  to  the  Epical  Hospital,  etc. 

(By JAMES  C.  WILSON,  M.D.,  of  Philada., 

IV.    The   Summer  and    itS    DiSeaSeS.     \      Lecturer    on  Physical  Diagnosis    in    Jefferson 

(         Medical  College,  etc. 

V    Fvp^inht  anH  How  tn  Parp  fnr  It  {By  GEORGE  c.  HARLAN,  M.D.,  of  Phila., 
v .  tyesigni,  ana  now  10  uare  Tor  it.  \   surgeon  to  the  mils  (Eye}  Hospital. 

f  By  J.  SOLIS  COHEN,  M.D.,  of  Philada., 
VI.    The  ThPOat  and  the  VOICe.  \      Lecturer  on  Diseases  of  the  Throat  in  Jefferson 

*          (         Medical  College. 

VII.  The  Winter  and  its  Dangers.      F££SSFSS££l. 2&£$Sa 
VIII.  The  Mouth  and  the  Teeth.          {^SSCSgf&S*1-'  °f  PhUada" 

IY      flnt.  Hnmoc  /By  HENRY  HARTSHORNE,  M.D.,  of  Phila., 

I  A.    U»UP  nuilieb.  |     Formerly  Prof,  of  Hygiene  in  Univer.  of  Pcnna. 

(By  L.  D.  BULKLEY,  M.D.,  of  New  York., 
X.    The   Skin   in  Health  and  Disease.-^      Physician  to  the  Skin  Department  of  the  DemiU 

(         Dispensary  and  of  the  New  York  Hospital. 

(  By  H.  C.  WOOD,  Jr.,  M.D.,  of  Philada., 
XI.     Brain  WOPk  and   Overwork.  \      Clinical  Professor  of  Nervous  Diseases  in  the 

(^         University  of  Pennsylvania,  etc. 

Other  volumes  are  in  preparation,  including  the  following  subjects:  "Preventable 
Diseases,"  "  Accidents  and  Emergencies,"  "  The  Towns  we  Live  In,"  "  Diet 
in  Health  and  Disease,"  "The  Art  of  Nursing,"  "School  and  Industrial 
Hygiene,"  etc.,  etc.  They  will  be  l6mo  in  size,  neatly  printed  on  tinted  paper,  and 
handsomely  bound  in  embossed  cloth.  Price,  50  cents. 

Mailed  free  upon  receipt  of  price. 

LINDSAY  &  BLAKISTON,  Publishers,  Philadelphia. 


.  Jy  CHAS.  H.  BURNETT,  M.D.,  of  Philada., 
I.     Hearing,   and   HOW  tO   Keep   It.        \      Surgeon  in  charge  of  PhUa.Disp.  for  Diseases  of 


Of 


